1.
Profession
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The term is a truncation of the term liberal profession, which is, in turn, an Anglicization of the French term profession libérale. Medieval and early modern tradition recognized only four professions, divinity, medicine, the military officer, just as some professions rise in status and power through various stages, others may decline. Disciplines formalized more recently, such as architecture, now have equally long periods of study associated with them, originally, any regulation of the professions was self-regulation through bodies such as the College of Physicians or the Inns of Court. With the growing role of government, statutory bodies have taken on this role. It may be resisted as limiting the freedom to innovate or to practice as in their professional judgement they consider best. An example was in 2008, when the British government proposed wide statutory regulation of psychologists, besides regulating access to a profession, professional bodies may set examinations of competence and enforce adherence to an ethical code. Typically, individuals are required by law to be qualified by a professional body before they are permitted to practice in that profession. However, in countries, individuals may not be required by law to be qualified by such a professional body in order to practice. This requirement is set out by the Educational Department Bureau of Hong Kong, Professions tend to be autonomous, which means they have a high degree of control of their own affairs, professionals are autonomous insofar as they can make independent judgments about their work. This usually means the freedom to exercise their professional judgement, however, it also has other meanings. Professional autonomy is often described as a claim of professionals that has to serve primarily their own interests, one major implication of professional autonomy is the traditional ban on corporate practice of the professions, especially accounting, architecture, medicine, and law. This means that in many jurisdictions, these professionals cannot do business through regular for-profit corporations, the obvious implication of this is that all equity owners of the professional business entity must be professionals themselves. This avoids the possibility of an owner of the firm telling a professional how to do his or her job. But because professional business entities are locked out of the stock market. Professions enjoy a social status, regard and esteem conferred upon them by society. This high esteem arises primarily from the social function of their work. All professions involve technical, specialized and highly skilled work often referred to as professional expertise, training for this work involves obtaining degrees and professional qualifications without which entry to the profession is barred. Updating skills through continuing education is required through training and this power is used to control its own members, and also its area of expertise and interests
2.
Farrier
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A farrier is a specialist in equine hoof care, including the trimming and balancing of horses hooves and the placing of shoes on their hooves, if necessary. A farrier combines some blacksmiths skills with some veterinarians skills to care for horses feet, historically, the jobs of farrier and blacksmith were practically synonymous, shown by the etymology of the word, farrier comes from Middle French, ferrier, from the Latin word ferrum. Modern day farriers usually specialize in horseshoeing, focusing their time, for this reason, farriers and blacksmiths are considered to be in separate, albeit related, trades. In the British Army, the Household Cavalry have farriers who march in parade in ceremonial dress and they are a familiar sight at the annual Trooping the Colour. There is also a farrier on call round the clock, twenty-four hours a day, in the United Kingdom, the Worshipful Company of Farriers is one of the Livery Companies of the City of London. The Farriers, or horseshoe makers, organised in 1356 and it received a Royal Charter of incorporation in 1571. Over the years, the Company has evolved from an association for horseshoe makers into an organisation for those devoted to equine welfare. A farriers routine work is primarily hoof trimming and shoeing, in ordinary cases, it is important to trim each hoof so it retains its proper orientation to the ground. If the animal has a work load, works on abrasive footing, needs additional traction, or has pathological changes in the hoof. Additional tasks for the farrier include dealing with injured or diseased hooves, horses with certain diseases or injuries may need remedial procedures for their hooves, or need special shoes. As a service-based industry, farriers must combine technical competence with horsemanship, self-employed farriers and those in partnerships may also require skill in running a small business. In countries such as the United Kingdom, it is illegal for other than registered farriers to call themselves a farrier or to carry out any farriery work. The primary aim of the Act is to prevent and avoid suffering by, however, in other countries, such as the United States, farriery is not regulated, no legal certification exists, and qualifications can vary. In the US, three organizations - the American Farriers Association, the Guild of Professional Farriers, and the Brotherhood of Working Farriers maintain voluntary certification programs for farriers, of these, the AFAs program is the largest with approximately 2800 certified farriers. Additionally, the AFA program has a reciprocity agreement with the Farrier Registration Council, within the certification programs offered by the AFA and the GPF, all farrier examinations are conducted by peer panels. Farriers who have received a certificate of completion for attending a school or course may represent themselves as having completed a particular course of study. Sometimes, usually for purposes of brevity, they use the term certified in advertising, for instance, farriers voluntarily registered with the American Association of Professional Farriers require at least 16 hours of continuing education every year to maintain their accreditation. Equine anatomy Equine forelimb anatomy Equine podiatry Household Cavalry Army Farriers Natural hoof care Rasp Worshipful Company of Farriers
3.
Metalsmith
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A metalsmith or simply smith is a craftsman fashioning useful items out of various metals. Smithing is one of the oldest metalworking occupations, shaping metal with a hammer is the archetypical component of smithing. Often the hammering is done while the metal is hot, having been heated in a forge, smithing can also involve the other aspects of metalworking, such as refining metals from their ores, casting it into shapes, and filing to shape and size. The prevalence of metalworking in the culture of recent centuries has led Smith, as a suffix, -smith connotes a meaning of a specialized craftsman—for example, wordsmith and tunesmith are nouns synonymous with writer or songwriter, respectively. In pre-industrialized times, smiths held high or special social standing since they supplied the tools needed for farming. This was especially true in some West African cultures, a metalsmith is one who works with or has the knowledge and the capacity of working with all metals. Today, this tool is still used by blacksmiths as it was traditionally. The term, metalsmith, often refers to artisans and craftpersons who practice their craft in many different metals, including gold, machinists are metalsmiths who produce high-precision parts and tools. The most advanced of these tools, CNC machines, are computer controlled and largely automated
4.
Wrought iron
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Wrought iron is an iron alloy with a very low carbon content in contrast to cast iron. It is a mass of iron with fibrous slag inclusions which gives it a grain resembling wood. Wrought iron is tough, malleable, ductile, corrosion-resistant and easily welded, before the development of effective methods of steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. A wrought product is one that has been worked by forging, extruding, rolling, hammering, etcetera, to change its form. Wrought iron is a worked iron product that is seldom produced today as other cheaper. Historically, a modest amount of iron was refined into steel. The demand for wrought iron reached its peak in the 1860s with the adaptation of ironclad warships, however, as properties such as brittleness of mild steel improved, it became less costly and more widely available than wrought iron, whose usage then declined. Wrought iron is no longer produced on a commercial scale, many products described as wrought iron, such as guard rails, garden furniture and gates, are actually made of mild steel. They retain that description because they are made to resemble objects which in the past were wrought by hand by a blacksmith, the word wrought is an archaic past participle of the verb to work, and so wrought iron literally means worked iron. Wrought iron is a term for the commodity, but is also used more specifically for finished iron goods. It was used in that sense in British Customs records. Cast iron, unlike wrought iron, is brittle and cannot be worked either hot or cold, Cast iron can break if struck with a hammer. In the 17th, 18th, and 19th centuries, wrought iron went by a variety of terms according to its form, origin. While the bloomery process produced wrought iron directly from ore, cast iron or pig iron were the materials used in the finery forge. Pig iron and cast iron have higher content than wrought iron. Cast and especially pig iron have excess slag which must be at least partially removed to produce quality wrought iron, at foundries it was common to blend scrap wrought iron with cast iron to improve the physical properties of castings. Fusion eventually became accepted as relatively more important than composition below a given low carbon concentration. Another difference is that steel can be hardened by heat treating, historically, wrought iron was known as commercially pure iron, however, it no longer qualifies because current standards for commercially pure iron require a carbon content of less than 0.008 wt%
5.
Steel
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Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and then Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product. Today, steel is one of the most common materials in the world and it is a major component in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft, ductile, and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and niobium. Additional elements are important in steel, phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
6.
Forging
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Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer or a die, Forging is often classified according to the temperature at which it is performed, cold forging, warm forging, or hot forging. For the latter two, the metal is heated, usually in a forge, forged parts can range in weight from less than a kilogram to hundreds of metric tons. Forging has been done by smiths for millennia, the products were kitchenware, hardware, hand tools, edged weapons, cymbals. Today, forging is a worldwide industry. Forging is one of the oldest known metalworking processes, the smithy or forge has evolved over centuries to become a facility with engineered processes, production equipment, tooling, raw materials and products to meet the demands of modern industry. In modern times, industrial forging is done either with presses or with powered by compressed air, electricity. These hammers may have reciprocating weights in the thousands of pounds, smaller power hammers,500 lb or less reciprocating weight, and hydraulic presses are common in art smithies as well. Some steam hammers remain in use, but they became obsolete with the availability of the other, more convenient, Forging can produce a piece that is stronger than an equivalent cast or machined part. As the metal is shaped during the process, its internal grain deforms to follow the general shape of the part. As a result, the grain is continuous throughout the part, additionally, forgings can target a lower total cost when compared to a casting or fabrication. Some metals may be forged cold, but iron and steel are almost always hot forged, hot forging prevents the work hardening that would result from cold forging, which would increase the difficulty of performing secondary machining operations on the piece. Also, while work hardening may be desirable in some circumstances, other methods of hardening the piece, such as heat treating, are more economical. Alloys that are amenable to precipitation hardening, such as most aluminium alloys and titanium, production forging involves significant capital expenditure for machinery, tooling, facilities and personnel. In the case of hot forging, a furnace is required to heat ingots or billets. In the case of drop forging operations, provisions must be made to absorb the shock, most forging operations use metal-forming dies, which must be precisely machined and carefully heat-treated to correctly shape the workpiece, as well as to withstand the tremendous forces involved. The main advantage of hot forging is that it can be more quickly and precisely. Cold forging typically results in work hardening of the piece, drop forging is a forging process where a hammer is raised and then dropped onto the workpiece to deform it according to the shape of the die
7.
Tinsmith
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A tinsmith, sometimes known as a whitesmith, tinner, tinker, tinman, or tinplate worker is a person who makes and repairs things made of tinware, or other light metals. By extension it can refer to the person who deals in tinware. A whitesmith may work with tin, pewter, or other materials, unlike blacksmiths, tinsmiths do the majority of their work on cold metal. The term is applied to metalworkers who do only finishing work – such as filing or polishing – on iron. Whitesmiths fabricate items such as tin or pewter cups, water pitchers, forks, spoons, the tinsmith, or white smith, learned his trade, like many other artisans, by serving an apprenticeship of 4 to 6 years with a master tinsmith. He learned first to make cake stamps, pill boxes and other simple items, next, he formed objects such as milk pails, basins, cake and pie pans. Later he tackled more complicated pieces such as chandeliers and crooked-spout coffee pots, after his apprenticeship was completed, he then became a journeyman, not yet being a master smith employing others. Many young tinsmiths took to the road as peddlers or tinkers in an effort to save money to open a shop in town. Tinplate consists of iron coated with tin and then run through rollers. This process was first discovered in the 16th century, but was not introduced to England until about the 1720s, previously Great Britain had imported most tinplate from Hamburg. The British Iron Act of 1750 prohibited the erection of new rolling mills, pure tin is an expensive and soft metal and it is not practical to use it alone. However it could be alloyed with lead and copper to make pewter or alloyed with copper alone to produce bronze, todays tinplate is mild steel electroplated with tin. Its non-rusting qualities make it an invaluable coating, however, its quality depends on the iron or steel being free from rust and the surface tin an unbroken coating. When you see rust on a piece of tinware it is because the tin coating has worn away or been cut in the metal, the respective properties of the metals mean that corrosion once started is likely to be rapid. The simple shapes made by the tinsmith required only a few basic tools, in addition to the big shears anchored in a hole in his bench he used hand snips and nippers for cutting. The tin was flattened on a made of a block of steel. Straight and curved anvils were used to turn and roll the edges of the tin, solder was then used to join the pieces together, a soldering iron and fire pot were needed to do this. Tinwares were being produced in London by the 1630s, being known as Crooked Lane Wares, the Worshipful Company of Tin Plate Workers were incorporated as a separate London Livery Company in 1670
8.
Wheelwright
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A wheelwright is a person who builds or repairs wooden wheels. The word is the combination of wheel and the word wright. This occupational name eventually became the English surname Wheelwright, why this should be so when the development of wheeled vehicles was nationwide, is unclear. The first known recording though is from the county of Essex and this was Walter Welwryhte, who appears in the Hundred Rolls for that county in the year 1273. This was during the first year of the reign of King Edward 1st of England, tradesmen made wheels for carts and wagons by first constructing the hub, the spokes and the rim/felloe segments and assembling them all into a unit working from the center of the wheel outwards. Most wheels were made from wood, but other materials have been used, such as bone and horn, for decorative or other purposes. After many centuries wheels evolved to be straked with iron, a method of nailing iron plates onto the felloes to protect against wear on the ground and to help bind the wheel together. During the industrial age, iron strakes were replaced by a solid iron tyre custom made by a blacksmith, tyre-bolts were less likely than tyre-nails to break off because they were flush finished and countersunk into the wheels outer surface also allowing for wear without wearing the bolt head away. During the second half of the 19th century, the use of pre-manufactured iron hubs and other wood, iron. Companies such as Henry Ford developed manufacturing processes that made the village wheelwright obsolete. With the onset of two wars, the trade soon went into decline and was very rare by the 1960s. However, owing to the efforts of organisations like the Worshipful Company of Wheelwrights, wheelwrights continue to operate in the UK. In modern times, wheelwrights continue to make and repair a wide variety of wheels, including those made from wood and banded by iron tyres. A modern wooden wheel generally consists of three parts, the Nave or hub at the centre of the wheel, the spokes radiating out from the centre. Generally the wheel would be bound by a steel or iron tyre depending on its historical period, sometimes Hickory is substituted for Oak and Ash as it is easier to bend for mass production and is quite springy for light wheels that require a bit of flexibility. The Elm is used for its grain, this prevents the nave from splitting with the force of the spokes being driven in tight. The Oak is used because it doesnt bend, compress or flex, the Ash is used for its flexibility and springy nature, this acts as a form of suspension and protects against shock damage. In the second half of the 20th century Wheelwright training faded away due to a lack of demand for new wooden wheels
9.
Fire scale
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Firescale, also known as firestain, is a layer of oxides that forms on the surface of metals when heated, as by a blacksmith heating a tool. On mixtures of silver and copper, such as sterling silver, at high temperatures, oxygen mixes with the copper to form cuprous oxide and then cupric oxide. Attempts to reduce this problem usually involve replacing oxygen with another gas such as hydrogen or ammonia and it may also appear on gold mixtures with a very high copper content. Firescale commonly develops during the process in jewellery manufacture, for example soldering a bale onto a finished pendant. The stain can only be removed by polishing, or removal of affected metal
10.
Valencian Museum of Ethnology
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The Valencian Museum of Ethnology is a museum located in the city of Valencia, mediterranean Spain. The museum mission defines it as cultural institution devoted to collect, research and communicate the tangible and intangible heritage related to traditional. The mission underlines that the museum aims to permanently question fundamental aspects of the culture, as the dynamics that built it and force it to evolve. The museum finally opened its doors in 1983 with four staff members, in a few years an interesting collection in agrarian technology was gathered constituting the core collection of the museum that has been enlarged in later years. As an institution rooted within the city of Valencian and the region of Valencia, at its site in the Centre Cultural la Beneficència in València city, the museum has a permanent exhibit presented in three sections, La ciutat viscuda. Ciutats valencianes en trànsit, 1800-1940, Horta i marjal and Secà i muntanya, in this center, the museum offers its programme of temporary exhibitions that revise topics related to the museum mission. Most of these are activities relate to traditional and popular culture and often bring multicultural perspectives, among the museum research projects, The Valencian Oral Memory Project stands out. This project started by the staff in the early 2000s, has been. The majority of articles are published in castillian or Catalan/valencian languages, the Museum has a library and document centre specialised in ethnology and anthropology. The facilities of the include the former psychiatric hospital of Bétera. The objectual collection of the museum has key examples of objects relating to traditional farming, after the initial effort to gather rural based material culture, the museum staff moved also into urban origin items. In later years collection policies have broaden to allow the arrival of more contemporary, most of the objects are of a valencian origin, only a small amount belongs to other geographical areas. In the last few years the section of the related to clothing has been increased greatly
11.
Anvil
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An anvil is a block with a hard surface on which another object is struck. The block is as massive as is practical, because the higher the inertia of the anvil, on a quality anvil the smiths hammer should rebound with almost as much energy as the smith puts into the downward stroke, ultimately making the smiths job easier and less physically strenuous. In most cases the anvil is used as a forging tool, before the advent of modern welding technology, it was a primary tool of metal workers. The great majority of modern anvils are made of cast or forged steel that has been heat treated, inexpensive anvils have been made of cast iron and low quality steel, but are considered unsuitable for serious use as they deform and lack rebound when struck. Because anvils are very ancient tools and were at one time very commonplace, the primary work surface of the anvil is known as the face. It is generally made of hardened steel and should be flat, any marks on the face will be transferred to the work. Also, sharp edges tend to cut into the metal being worked, the face is hardened and tempered to resist the blows of the smiths hammer, so the anvil face does not deform under repeated use. A hard anvil face also reduces the amount of force lost in each hammer blow. Hammers, tools, and work pieces of hardened steel should never directly strike the face with full force, as they may damage it. The horn of the anvil is a conical projection used to form various shapes and is generally unhardened steel or iron. The horn is used mostly in bending operations and it also is used by some smiths as an aid in drawing down stock. Some anvils, mainly European, are made with two horns, one square and one round, also, some anvils are made with side horns or clips for specialized work. The step is that area of the anvil between the horn and the face, the hardie hole is a square hole into which specialized forming and cutting tools, called Hardy tools, are placed. It is also used in punching and bending operations, the pritchel hole is a small round hole that is present on most modern anvils. Some anvils have more than one and it is used mostly for punching. At times, smiths will fit a second tool to this hole to allow the more flexibility when using more than one anvil tool. An anvil needs to be placed upon a base made from an impact. It requires being fastened firmly to the base, so it not move when struck with a hammer
12.
Chisel
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The handle and blade of some types of chisel are made of metal or of wood with a sharp edge in it. Chiselling use involves forcing the blade into some material to cut it, the driving force may be applied by pushing by hand, or by using a mallet or hammer. In industrial use, a ram or falling weight drives a chisel into the material. A gouge, one type of chisel, serves - particularly in woodworking, woodturning, gouges most frequently produce concave surfaces. A gouge typically has a U-shaped cross-section, chisel comes from the Old French cisel, modern ciseau, Late Latin cisellum, a cutting tool, from caedere, to cut. Chisels have a variety of uses. Many types of chisel have been devised, each suited to its intended use. Different types of chisel may be constructed differently, in terms of blade width or length, as well as shape. They may have a wooden or plastic handle attached using a tang or socket, woodworking chisels range from small hand tools for tiny details, to large chisels used to remove big sections of wood, in roughing out the shape of a pattern or design. Typically, in woodcarving, one starts with a larger tool, one of the largest types of chisel is the slick, used in timber frame construction and wooden shipbuilding. There are many types of woodworking chisels used for specific purposes, such as, Butt chisel, short chisel with beveled sides and straight edge for creating joints. Carving chisels, used for designs and sculpting, cutting edges are many, such as gouge, skew, parting, straight, paring. Corner chisel, resembles a punch and has an L-shaped cutting edge, cleans out square holes, mortises and corners with 90 degree angles. Bevel edge chisel, can get into acute angles with its bevelled edges, flooring chisel, cuts and lifts flooring materials for removal and repair, ideal for tongue-and-groove flooring. Framing chisel, usually used with mallet, similar to a chisel, except it has a longer. Slick, a large chisel driven by pressure, never struck. Mortise chisel, thick, rigid blade with cutting edge and deep, slightly tapered sides to make mortises. Paring chisel, has a long blade ideal for cleaning grooves, skew chisel, has a 60 degree cutting angle and is used for trimming and finishing
13.
Forge
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A forge is a type of hearth used for heating metals, or the workplace where such a hearth is located. The forge is used by the smith to heat a piece of metal to a temperature where it easier to shape by forging. The metal is transported to and from the forge using tongs, the slack tub also provides water to control the fire in the forge. A forge typically uses bituminous coal, industrial coke or charcoal as the fuel to heat metal, the designs of these forges have varied over time, but whether the fuel is coal, coke or charcoal the basic design has remained the same. The forge fire in this type of forge is controlled in three ways, amount of air, volume of fuel, and shape of the fuel/fire, traditionally hearths have been constructed of mud brick, fired brick, stone, or later, constructed of iron. During operation, fuel is placed in or on the hearth, a source of moving air, such as a fan or bellows, introduces additional air into the fire through the tuyere. With additional air, the fire more fuel and burns hotter (and cleaner - smoke can be thought of as escaped potential fuel. A blacksmith balances the fuel and air in the fire to suit particular kinds of work, often this involves adjusting and maintaining the shape of the fire. In a typical coal forge, a firepot will be centered in a flat hearth, the tuyere will enter the firepot at the bottom. In operation, the hot core of the fire will be a ball of burning coke in, the heart of the fire will be surrounded by a layer of hot but not burning coke. Around the unburnt coke will be a layer of coal being transformed into coke by the heat of the fire. If a larger fire is necessary, the smith increases the air flowing into the fire as well as feeding and deepening the coke heart, the smith can also adjust the length and width of the fire in such a forge to accommodate different shapes of work. The major variation from the forge and fire just described is a draft where there is no fire pot. Coke and charcoal may be burned in the forges that use coal, but since there is no need to convert the raw fuel at the heart of the fire. A gas forge typically uses propane or natural gas as the fuel, one common, efficient design uses a cylindrical forge chamber and a burner tube mounted at a right angle to the body. The chamber is lined with refractory materials such as a hard castable refractory ceramic or a soft ceramic thermal blanket. The burner mixes fuel and air which are ignited at the tip, the air pressure, and therefore heat, can be increased with a mechanical blower or by taking advantage of the Venturi effect. A small forge can even be carved out of a single soft firebrick, the primary advantage of a gas forge is ease of use, particularly for a novice
14.
Coke (fuel)
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Coke is a fuel with few impurities and a high carbon content, usually made from coal. It is the carbonaceous material derived from destructive distillation of low-ash. Cokes made from coal are grey, hard, and porous, while coke can be formed naturally, the commonly used form is man-made. The form known as coke, or pet coke, is derived from oil refinery coker units or other cracking processes. Coke is used in preparation of producer gas which is a mixture of carbon monoxide, producer gas is produced by passing air over red-hot coke. Coke is also used to water gas. Historical sources dating to the 4th century describe the production of coke in ancient China, the Chinese first used coke for heating and cooking no later than the ninth century. By the first decades of the century, Chinese ironworkers in the Yellow River valley began to fuel their furnaces with coke. In 1589 a patent was granted to Thomas Proctor and William Peterson for making iron and steel and melting lead with earth-coal, sea-coal, turf, the patent contains a distinct allusion to the preparation of coal by cooking. In 1590 a patent was granted to the Dean of York to purify pit-coal, in 1620 a patent was granted to a company composed of William St. John, Robert Follensbee and other knights, mentioning the use of coke in smelting ores and manufacturing metals. In 1627 a patent was granted to Sir John Hacket and Octavius de Strada for a method of rendering sea-coal and pit-coal as useful as charcoal for burning in houses, without offense by smell or smoke. In 1603 Hugh Plat suggested that coal might be charred in an analogous to the way charcoal is produced from wood. In 1709 Abraham Darby I established a coke-fired blast furnace to produce cast iron, cokes superior crushing strength allowed blast furnaces to become taller and larger. The ensuing availability of iron was one of the factors leading to the Industrial Revolution. Before this time, iron-making used large quantities of charcoal, produced by burning wood, in the late 18th century, brick beehive ovens were developed, which allowed more control over the burning process. In 1768 John Wilkinson built a more practical oven for converting coal into coke, with greater skill in the firing, covering and quenching of the heaps, yields were increased from about 33 per cent to 65 per cent by the middle of the 19th century. The Scottish iron industry expanded rapidly in the second quarter of the 19th century. In 1802 a battery of beehives was set up near Sheffield, by 1870, there were 14,000 beehive ovens in operation on the West Durham coalfields, capable of producing 4.2 million tons of coke
15.
Oxy-fuel welding and cutting
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Oxy-fuel welding and oxy-fuel cutting are processes that use fuel gases and oxygen to weld and cut metals, respectively. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903, pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material in a room environment. In recent decades it has been obsolesced in almost all industrial uses due to various arc welding methods offering more consistent mechanical weld properties, gas welding is still used for metal-based artwork and in smaller home based shops, as well as situations where accessing electricity would present difficulties. In oxy-fuel welding, a torch is used to weld metals. Welding metal results when two pieces are heated to a temperature that produces a shared pool of molten metal, the molten pool is generally supplied with additional metal called filler. Filler material depends upon the metals to be welded, in oxy-fuel cutting, a torch is used to heat metal to its kindling temperature. A stream of oxygen is then trained on the metal, burning it into an oxide that flows out of the kerf as slag. Torches that do not mix fuel with oxygen are not considered oxy-fuel torches, most metals cannot be melted with a single-tank torch. Consequently, single-tank torches are typically suitable for soldering and brazing, oxy-gas torches are or have been used for, Welding metal, see below. Depositing metal to build up a surface, as in hardfacing, also, oxy-hydrogen flames are used, in stone working for flaming where the stone is heated and a top layer crackles and breaks. A steel circular brush is attached to a grinder and used to remove the first layer leaving behind a bumpy surface similar to hammered bronze. In the glass industry for fire polishing, in jewelry production for water welding using a water torch. in automotive repair, removing a seized bolt. Formerly, to heat lumps of quicklime to obtain a white light called limelight. Formerly, in works, as platinum is fusible only in the oxyhydrogen flame. The apparatus used in gas welding consists basically of an oxygen source and this sort of torch can also be used for soldering and brazing. The cylinders are carried in a special wheeled trolley. There have been examples of oxyhydrogen cutting sets with small gas cylinders worn on the back in a backpack harness, for rescue work. There are also examples of pressurized liquid fuel cutting torches, usually using gasoline and these are used for their increased portability
16.
Blow torch
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A blowtorch, or blowlamp, is a fuel-burning tool used for applying flame and heat to various applications, usually metalworking. Early blowtorches used liquid fuel, carried in a reservoir attached to the lamp. Their fuel reservoir is disposable or refillable by exchange, the term blowlamp usually refers to liquid-fuelled torches still used in the UK. Liquid-fuelled torches are pressurized by a hand pump, while gas torches are self-pressurized by the fuel evaporation. Fuel torches are available in a vast range of size and output power, the term blowtorch applies to the smaller and lower temperature range of these. Blowtorches are typically a single unit, with their draught supplied by a natural draught of air. The larger torches may have a fuel reservoir placed on the ground. This is common for butane- or propane-fuelled gas torches, but also applies to the older, many torches now use a hose-supplied gas feed, which is often mains gas. They may also have a supply, from either an air blower or an oxygen cylinder. Both of these larger and more powerful designs are commonly described as blowtorches, while the term blowtorch is usually reserved for the smaller. The archaic term blowpipe is sometimes used in relation to oxy-acetylene welding torches. The blowtorch is of ancient origin and was used as a tool by gold and they began literally as a blown lamp, a wick oil lamp with a mouth-blown tube alongside the flame. This type of lamp, with fuel, continued to be in use for such small tasks into the late 20th century. In 1797 or in 1799 German inventor August von Marquardt invented a blowtorch in Eberswalde, another early blow pipe patent comes from USA, dated May 13,1856. In 1882, a new vaporizing technique was developed by Carl Richard Nyberg in Sweden, and the year after and it was quickly copied or licensed by many other manufacturers. The US blowtorch was independently developed with a flared base and was fuelled by gasoline, whereas the European versions used kerosene for safety. There remain several manufacturers producing brass blowtorches in India, China, the blowtorch is commonly used where a diffuse high temperature naked flame heat is required but not so hot as to cause combustion or welding. Temperature applications, soldering, brazing, softening paint for removal, melting roof tar and it is also used in cooking, one common use is for the creation of the layer of hard caramelized sugar in a crème brûlée
17.
Induction heating
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Induction heating is the process of heating an electrically conducting object by electromagnetic induction, through heat generated in the object by eddy currents. An induction heater consists of an electromagnet, and an electronic oscillator that passes a high-frequency alternating current through the electromagnet, the rapidly alternating magnetic field penetrates the object, generating electric currents inside the conductor called eddy currents. The eddy currents flowing through the resistance of the heat it by Joule heating. In ferromagnetic materials like iron, heat may also be generated by magnetic hysteresis losses, the frequency of current used depends on the object size, material type, coupling and the penetration depth. An important feature of the heating process is that the heat is generated inside the object itself. Thus objects can be heated very rapidly, in addition there need not be any external contact, which can be important where contamination is an issue. It is also used in induction cooktops for heating containers of food, induction heating allows the targeted heating of an applicable item for applications including surface hardening, melting, brazing and soldering and heating to fit. Iron and its alloys respond best to induction heating, due to their ferromagnetic nature, eddy currents can, however, be generated in any conductor, and magnetic hysteresis can occur in any magnetic material. Induction heating has been used to heat liquid conductors and also gaseous conductors, induction heating is often used to heat graphite crucibles and is used extensively in the semiconductor industry for the heating of silicon and other semiconductors. Utility frequency induction heating is used for lower cost industrial applications as inverters are not required. An induction furnace uses induction to heat metal to its melting point, once molten, the high-frequency magnetic field can also be used to stir the hot metal, which is useful in ensuring that alloying additions are fully mixed into the melt. Most induction furnaces consist of a tube of water-cooled copper rings surrounding a container of refractory material, induction furnaces are used in most modern foundries as a cleaner method of melting metals than a reverberatory furnace or a cupola. Sizes range from a kilogram of capacity to a hundred tonnes capacity, induction furnaces often emit a high-pitched whine or hum when they are running, depending on their operating frequency. Metals melted include iron and steel, copper, aluminium, because it is a clean and non-contact process it can be used in a vacuum or inert atmosphere. Vacuum furnaces make use of heating for the production of specialty steels. A similar, smaller-scale process is used for induction welding, plastics may also be welded by induction, if they are either doped with ferromagnetic ceramics or by metallic particles. Seams of tubes can be welded this way, currents induced in a tube run along the open seam and heat the edges resulting in a temperature high enough for welding. At this point the seam edges are forced together and the seam is welded, the RF current can also be conveyed to the tube by brushes, but the result is still the same – the current flows along the open seam, heating it
18.
Black-body radiation
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Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body. It has a spectrum and intensity that depends only on the bodys temperature. The thermal radiation emitted by many ordinary objects can be approximated as black-body radiation. A black-body at room temperature appears black, as most of the energy it radiates is infra-red, when it becomes a little hotter, it appears dull red. As its temperature increases further it eventually becomes blue-white, although planets and stars are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is used as a first approximation for the energy they emit. Black holes are near-perfect black bodies, in the sense that they absorb all the radiation that falls on them and it has been proposed that they emit black-body radiation, with a temperature that depends on the mass of the black hole. The term black body was introduced by Gustav Kirchhoff in 1860, Black-body radiation is also called thermal radiation, cavity radiation, complete radiation or temperature radiation. Black-body radiation has a characteristic, continuous spectrum that depends only on the bodys temperature. As the temperature increases past about 500 degrees Celsius, black start to emit significant amounts of visible light. Viewed in the dark by the eye, the first faint glow appears as a ghostly grey. When the body appears white, it is emitting a substantial fraction of its energy as ultraviolet radiation, Black-body radiation provides insight into the thermodynamic equilibrium state of cavity radiation. Instead, in theory the occupation numbers of the modes are quantized, cutting off the spectrum at high frequency in agreement with experimental observation. The study of the laws of black bodies and the failure of classical physics to describe them helped establish the foundations of quantum mechanics, all normal matter emits electromagnetic radiation when it has a temperature above absolute zero. The radiation represents a conversion of a thermal energy into electromagnetic energy. It is a process of radiative distribution of entropy. Conversely all normal matter absorbs electromagnetic radiation to some degree, an object that absorbs all radiation falling on it, at all wavelengths, is called a black body. When a black body is at a temperature, its emission has a characteristic frequency distribution that depends on the temperature. Its emission is called black-body radiation, the concept of the black body is an idealization, as perfect black bodies do not exist in nature
19.
Swarf
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Swarf or chips can be small particles, long, stringy tendrils, slag-like waste, or stone fragments and dust. Some of these terms are mass nouns and some of them are count nouns, the rest of this article discusses metalworking swarf. Wood swarf is discussed at sawdust, chips can be extremely sharp, and this creates a safety problem, as they can cause serious injuries if not handled correctly. Depending on the composition of the material, it can persist in the environment for a time before degrading. This, combined with the size of some chips, allows them to disperse widely by piggy-backing on soft materials. It is standard training for machinists, and usually a standing workplace rule, some machine tool manuals proscribe this practice both for safety and for the preservation of way wipers and bearing seals. It is not uncommon for chips flying off the cutter to be ejected with great force, due to its high surface area, swarf composed of some reactive metals can be highly flammable. Swarf stored in piles or bins may also spontaneously combust, especially if the swarf is coated with cutting oil, to extinguish swarf fires, a special fire extinguisher is needed, designed for fighting Class D fires. Optimum cutting efficiencies often generate long spring-like swarf and this is hard to deal with as it is bulky and can clog the nozzle of a shop vac. Clean-up and disposal of this continuous-cutting swarf is made simpler by using a tool with a chip-breaker. This results in denser, more manageable waste, chip breaking tool geometry is generally designed to break the chip by having it curl back onto itself. This action produces many small spiral shaped rings instead of one long helical chip, disposing of swarf is a tedious but necessary task. Metal swarf can usually be recycled, and this is the method of disposal due to the environmental concerns regarding potential contamination with cutting fluid or tramp oil. The ideal way to remove these liquids is by the use of a centrifuge which will separate the fluids from the metal, small bundles of stainless steel or bronze swarf are sold as excellent scourers for dishwashing or cleaning encrustations of dirt. Financial There is almost always some money to be made from the stream of recycled chips, whether by the scrap processor, the scrap value of the metal is a net gain beyond any costs of handling and transporting the chips. Machine shops are required by the scrap collector to, segregate metal types it is usually not required to segregate particular alloys segregate solid chunks from chips. Drain and/or centrifuge all cutting fluid and way oil out of the chips
20.
Swaging
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Swaging is a forging process in which the dimensions of an item are altered using dies into which the item is forced. Swaging is usually a cold working process, however, it is sometimes done as a hot working process, the term swage can apply to the process of swaging, or to a die or tool used for swaging. The term swage comes from the Old French term souage, meaning groove or ornamental moulding. Swages were originally tools of the trade, used for forming metal into various shapes that were too intricate to make with a hammer alone. Swages called fullers are often used in bladesmithing for making grooves in swords, swage blocks are anvil-like dies with various shapes forged into them, which are also used for forming metal. Blacksmithing swages are typically tools with faces of various shapes, sometimes with handles for holding or pegs for attaching to an anvil, swage is most often pronounced /ˈsweɪdʒ/. Another pronunciation sometimes heard in the industries is /ˈswɛdʒ/. As a general manufacturing process swaging may be broken up into two categories, the first category of swaging involves extrusion of the workpiece, forcing it through a confining die to reduce its diameter, similar to the process of drawing wire. This may also be referred to as tube swaging, the second category involves two or more dies used to hammer a round workpiece into a smaller diameter. This process is usually called rotary swaging or radial forging, tubes may be tagged using a rotary swager, which allows them to be drawn on a draw bench. Swaging is normally the method of choice for precious metals since there is no loss of material in the process, rotary swaging process is usually a cold working process, used to reduce the diameter, produce a taper, or add a point to a round workpiece. It can also impart internal shapes in hollow workpieces through the use of a mandrel, swaging a bearing into a housing means either flaring its grooves lips onto the chamfer of the housing, or flaring the housings material over the edge of the bearing. The flaring is done with a pair of rolls that travel around the hole and are fed down into the part, grease is often used to lubricate this swaging process, which is also called roller swaging. A swaging machine works by using two or four split dies which separate and close up to 2000 times a minute and this action is achieved by mounting the dies into the machines spindle which is rotated by a motor. The spindle is mounted inside a cage containing rollers, there are two basic types of rotary swaging machine, the standard, and the butt swaging machine. A butt swaging machine works by having sets of wedges that close the dies onto the workpiece by inserting them between the rollers and the dies, normally by the use of a foot pedal. Swages are used for shaping the metal in various ways, to increase its beauty or its fit for a desired purpose, in printed circuit board assembly individual connector pins are sometimes pressed/swaged into place using an arbor press. Some pins have an end that is pressed over by the arbors tool to form a mushroom shaped retaining head
21.
Fuller (metalworking)
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In metalworking, a fuller is a tool used to form metal when hot. The fuller has a rounded, either cylindrical or parabolic, nose, the shank of the lower fuller allows the fuller to be inserted into the hardy hole of the anvil. Upper fullers furthermore come in straight or cross varieties, depending on the orientation of the relative to the face. The fuller is used mainly to spread the metal, the fuller is placed against the metal stock, and then either the fuller or the stock is struck with a hammer. The rounded nose of the fuller spreads the metal more efficiently than the face of the hammer. The process leaves ridges in the stock, which may then be flattened out later with the hammer or other tools, fuller, a groove on a blade often created by fullering Fullers and fullering
22.
Ductility
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In materials science, ductility is a solid materials ability to deform under tensile stress, this is often characterized by the materials ability to be stretched into a wire. Malleability, a property, is a materials ability to deform under compressive stress. Both of these properties are aspects of plasticity, the extent to which a solid material can be plastically deformed without fracture. Also, these properties are dependent on temperature and pressure. Ductility and malleability are not always coextensive – for instance, while gold has high ductility and malleability, lead has low ductility, the word ductility is sometimes used to encompass both types of plasticity. Ductility is especially important in metalworking, as materials that crack, break or shatter under stress cannot be manipulated using metal-forming processes such as hammering, rolling, malleable materials can be formed cold using stamping or pressing, whereas brittle materials may be cast or thermoformed. High degrees of ductility occur due to bonds, which are found predominantly in metals. In metallic bonds valence shell electrons are delocalized and shared between many atoms, the delocalized electrons allow metal atoms to slide past one another without being subjected to strong repulsive forces that would cause other materials to shatter. Ductility can be quantified by the fracture strain ε f, which is the strain at which a test specimen fractures during a uniaxial tensile test. Another commonly used measure is the reduction of area at fracture q, the ductility of steel varies depending on the alloying constituents. Increasing levels of carbon decrease ductility, many plastics and amorphous solids, such as Play-Doh, are also malleable. The most ductile metal is platinum and the most malleable metal is gold, DBTT is important since, once a material is cooled below the DBTT, it has a much greater tendency to shatter on impact instead of bending or deforming. For example, zamak 3 exhibits good ductility at room temperature, DBTT is a very important consideration in selecting materials that are subjected to mechanical stresses. A similar phenomenon, the transition temperature, occurs with glasses and polymers. In some materials the transition is sharper than others and typically requires a temperature-sensitive deformation mechanism and this can be problematic for steels with a high ferrite content. This famously resulted in serious hull cracking in Liberty ships in colder waters during World War II, DBTT can also be influenced by external factors such as neutron radiation, which leads to an increase in internal lattice defects and a corresponding decrease in ductility and increase in DBTT. The most accurate method of measuring the DBTT of a material is by fracture testing, typically four point bend testing at a range of temperatures is performed on pre-cracked bars of polished material. For experiments conducted at higher temperatures, dislocation activity increases, the temperature at which this occurs is the ductile–brittle transition temperature
23.
Plasticine
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Plasticine, a brand of modelling clay, is a putty-like modelling material made from calcium salts, petroleum jelly and aliphatic acids. The name is a trademark of Flair Leisure Products plc. Plasticine is used extensively for childrens play, but also as a medium for more formal or permanent structures. Because of its property, it is a popular choice of material for stop-motion animation. The brand-name clay is mentioned in music, such as the porters in Lucy in the Sky with Diamonds. William Harbutt, an art teacher in Bath, England, formulated Plasticine in 1897, Harbutt wanted a non-drying clay for his sculpture students. He created a non-toxic, sterile, soft and malleable clay that did not dry on exposure to air, Harbutt received a patent in 1899 and commercial production started at a factory in Bathampton in 1900. Four colours were produced for sale to the public. Plasticine was popular with children, was used in schools for teaching art. Plasticine is approximately 65% bulking agent, 10% petroleum jelly, 5% lime and 10% lanolin and it cannot be hardened by firing, melts when exposed to heat, and is flammable at higher temperatures. Harbutt patented a different formulation in 1915, which added wool fibres to give plasticine a stronger composition intended for ear plugs, and as a sterile dressing for wounds and burns. The Harbutt company marketed Plasticine as a toy by producing modelling kits based on characters from childrens stories, such as Noddy. The original Plasticine factory was destroyed by fire in 1963 and replaced by a modern building, the Harbutt company produced Plasticine in Bathampton until 1983, when production was moved to Thailand. The Colorforms company was the major American licensee of Plasticine from 1979 until at least 1984, apparently, the use of a different chalk compound caused a product inconsistency, and the US version was considered inferior to the original mix. Bluebird Toys plc acquired Plasticine through its purchase of Peter Pan, in 1998, Mattel bought Bluebird and the brand was sold to Humbrol Ltd, famous for its model paints and owner of the Airfix model kit brand. Flair Leisure licensed the brand from Humbrol in 2005 and relaunched Plasticine and it acquired the brand outright, when Humbrol went into administration a year later. A similar product, Kunst-Modellierthon, was invented by Franz Kolb of Munich and this product is still available, known as Münchner Künstler Plastilin. In Italy, the product Pongo is also marketed as plastilina, Play-Doh, which is based on flour, salt and water, dries on exposure to air
24.
Titanium
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Titanium is a chemical element with symbol Ti and atomic number 22. It is a transition metal with a silver color, low density. Titanium is resistant to corrosion in sea water, aqua regia, titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and it is named by Martin Heinrich Klaproth for the Titans of Greek mythology. The metal is extracted from its principal mineral ores by the Kroll, the most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride, a component of smoke screens and catalysts, and titanium trichloride, the two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, there are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant. Although they have the number of valence electrons and are in the same group in the periodic table. As a metal, titanium is recognized for its high strength-to-weight ratio and it is a strong metal with low density that is quite ductile, lustrous, and metallic-white in color. The relatively high melting point makes it useful as a refractory metal and it is paramagnetic and has fairly low electrical and thermal conductivity. Commercial grades of titanium have ultimate tensile strength of about 434 MPa, equal to that of common, low-grade steel alloys, titanium is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys achieve tensile strengths of over 1400 MPa, however, titanium loses strength when heated above 430 °C. Titanium is not as hard as some grades of heat-treated steel, it is non-magnetic, machining requires precautions, because the material might gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a limit that guarantees longevity in some applications. The metal is an allotrope of an hexagonal α form that changes into a body-centered cubic β form at 882 °C. The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls, similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but metastable at ambient pressures. This phase is usually hexagonal or trigonal and can be considered to be due to a soft longitudinal acoustic phonon of the β phase causing collapse of planes of atoms, like aluminium and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air. Titanium readily reacts with oxygen at 1,200 °C in air and it is, however, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation. When it first forms, this layer is only 1–2 nm thick but continues to grow slowly
25.
Welding
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In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material that cools to form a joint that is usually stronger than the base material. Pressure may also be used in conjunction with heat, or by itself, although less common, there are also solid state welding processes such as friction welding or shielded active gas welding in which metal does not melt. Some of the best known welding methods include, Oxy-fuel welding - also known as oxyacetylene welding or oxy welding, uses fuel gases and oxygen to weld and cut metals. Shielded metal arc welding – also known as stick welding or electric welding, the electrode holder holds the electrode as it slowly melts away. Slag protects the weld puddle from atmospheric contamination, gas tungsten arc welding – also known as TIG, uses a non-consumable tungsten electrode to produce the weld. The weld area is protected from contamination by an inert shielding gas such as argon or helium. Flux-cored arc welding – almost identical to MIG welding except it uses a special tubular wire filled with flux, it can be used with or without shielding gas, submerged arc welding – uses an automatically fed consumable electrode and a blanket of granular fusible flux. The molten weld and the arc zone are protected from contamination by being submerged under the flux blanket. Electroslag welding – a highly productive, single pass welding process for thicker materials between 1 inch and 12 inches in a vertical or close to vertical position. Electric resistance welding - a welding process that produces coalescence of laying surfaces where heat to form the weld is generated by the resistance of the material. In general, an efficient method, but limited to relatively thin material, many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound. While often a process, welding may be performed in many different environments, including in open air, under water. Welding is an undertaking and precautions are required to avoid burns, electric shock, vision damage, inhalation of poisonous gases and fumes. Until the end of the 19th century, the welding process was forge welding. Arc welding and oxyfuel welding were among the first processes to develop late in the century, Welding technology advanced quickly during the early 20th century as the world wars drove the demand for reliable and inexpensive joining methods. Developments continued with the invention of laser welding, electron beam welding, magnetic pulse welding. Today, the continues to advance. Robot welding is commonplace in industrial settings, and researchers continue to develop new welding methods, the history of joining metals goes back several millennia
26.
Arc welding
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Arc welding is a process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals when cool result in a binding of the metals. It is a type of welding that uses a power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct or alternating current, and consumable or non-consumable electrodes, the welding region is usually protected by some type of shielding gas, vapor, or slag. Arc welding processes may be manual, semi-automatic, or fully automated, first developed in the late part of the 19th century, arc welding became commercially important in shipbuilding during the Second World War. Today it remains an important process for the fabrication of steel structures and vehicles, to supply the electrical energy necessary for arc welding processes, a number of different power supplies can be used. The most common classification is constant current power supplies and constant voltage power supplies, in arc welding, the voltage is directly related to the length of the arc, and the current is related to the amount of heat input. This is important because in manual welding, it can be difficult to hold the electrode perfectly steady, and as a result, the arc length and thus voltage tend to fluctuate. In these processes, arc length is constant, since any fluctuation in the distance between the wire and the base material is quickly rectified by a large change in current. The direction of current used in arc welding also plays an important role in welding, consumable electrode processes such as shielded metal arc welding and gas metal arc welding generally use direct current, but the electrode can be charged either positively or negatively. In welding, the positively charged anode will have a greater concentration and, as a result. If the electrode is charged, it will melt more quickly, increasing weld penetration. Alternatively, a negatively charged electrode results in more shallow welds, non-consumable electrode processes, such as gas tungsten arc welding, can use either type of direct current, as well as alternating current. Alternating current rapidly moves between two, resulting in medium-penetration welds. Duty cycle is an equipment specification which defines the number of minutes, within a 10-minute period. For example, an 80 A welder with a 60% duty cycle must be rested for at least 4 minutes after 6 minutes of continuous welding, failure to observe duty cycle limitations could damage the welder. Commercial- or professional-grade welders typically have a 100% duty cycle, one of the most common types of arc welding is shielded metal arc welding, which is also known as manual metal arc welding or stick welding. An electric current is used to strike an arc between the material and a consumable electrode rod or stick. The electrode core itself acts as filler material, making a separate filler unnecessary, the process is very versatile, requiring little operator training and inexpensive equipment
27.
Heat treating
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Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical, Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering, normalizing and quenching. Metallic materials consist of a microstructure of small crystals called grains or crystallites, the nature of the grains is one of the most effective factors that can determine the overall mechanical behavior of the metal. Heat treatment provides an efficient way to manipulate the properties of the metal by controlling the rate of diffusion, Heat treating is often used to alter the mechanical properties of a metallic alloy, manipulating properties such as the hardness, strength, toughness, ductility, and elasticity. The crystal structure consists of atoms that are grouped in a specific arrangement. In most elements, this order will rearrange itself, depending on conditions like temperature and pressure and this rearrangement, called allotropy or polymorphism, may occur several times, at many different temperatures for a particular metal. When in the state, the process of diffusion causes the atoms of the dissolved element to spread out. If the alloy is cooled to a state, the atoms of the dissolved constituents may migrate out of the solution. This type of diffusion, called precipitation, leads to nucleation and this forms a microstructure generally consisting of two or more distinct phases. Steel that has been cooled slowly, for instance, forms a structure composed of alternating layers of ferrite and cementite. After heating the steel to the phase and then quenching it in water. This is due to the fact that the steel will change from the phase to the martensite phase after quenching. It should be noted that some pearlite or ferrite may be present if the quench did not rapidly cool off all the steel, unlike iron-based alloys, most heat treatable alloys do not experience a ferrite transformation. In these alloys, the nucleation at the grain-boundaries often reinforces the structure of the crystal matrix, typically a slow process, depending on temperature, this is often referred to as age hardening. Many metals and non-metals exhibit a transformation when cooled quickly. When a metal is cooled quickly, the insoluble atoms may not be able to migrate out of the solution in time. This is called a diffusionless transformation, when the crystal matrix changes to its low temperature arrangement, the atoms of the solute become trapped within the lattice
28.
Case-hardening
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For iron or steel with low carbon content, which has poor to no hardenability of its own, the case-hardening process involves infusing additional carbon into the surface layer. The term face hardening is used to describe this technique. Because hardened metal is more brittle than softer metal, through-hardening is not always a suitable choice for uses where the metal part is subject to certain kinds of stress. In such circumstances, case-hardening can provide a part that will not fracture, early iron smelting made use of bloomeries, which produced two layers of metal, one with a very low carbon content that is worked into wrought iron, and the rest a high carbon cast iron. Since the high carbon iron is hot short, meaning it fractures and crumbles when forged, the wrought iron, with nearly no carbon in it, was very malleable and ductile but not very hard. Case-hardening involves packing the low-carbon iron within a high in carbon. This forms a surface layer of higher carbon steel, with the carbon content gradually decreasing deeper from the surface. The resulting product combines much of the toughness of a steel core, with the hardness. This carburizing package is then heated to a high temperature but still under the point of the iron. The longer the package is held at the temperature, the deeper the carbon will diffuse into the surface. The resulting case-hardened part may show distinct surface discoloration, if the material is mixed organic matter as described above. The steel darkens significantly, and shows a pattern of black, blue and purple, caused by the various compounds formed from impurities in the bone. This oxide surface works similarly to bluing, providing a degree of corrosion resistance, case colouring refers to this pattern and is commonly encountered as a decorative finish on firearms. Case-hardened steel combines extreme hardness and extreme toughness, something which is not readily matched by homogeneous alloys, carbon itself is solid at case-hardening temperatures and so is immobile. Transport to the surface of the steel was as gaseous carbon monoxide, generated by the breakdown of the carburising compound and this takes place with pure carbon but too slowly to be workable. Although oxygen is required for this process it is re-circulated through the CO cycle, the sealing is necessary to stop the CO either leaking out or being oxidised to CO2 by excess outside air. It is a common fallacy that case-hardening was done with bone. Although bone was used, the main donor was hoof
29.
Bluing (steel)
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Bluing is a passivation process in which steel is partially protected against rust, and is named after the blue-black appearance of the resulting protective finish. True gun bluing is a conversion coating resulting from an oxidizing chemical reaction with iron on the surface selectively forming magnetite. Black oxide provides minimal protection against corrosion, unless treated with a water-displacing oil to reduce wetting. A distinction can be made between traditional bluing and some more modern black oxide coatings, although bluing is a subset of black oxide coatings. In comparison, rust, the red oxide of iron, undergoes a large volume change upon hydration, as a result. Cold, Hot, Rust Blue and Fume Blue are oxidizing processes simply referred to as bluing, cold bluing is generally a selenium dioxide based compound that colours steel black, or more often a very dark grey. It is a product to apply evenly, offers minimal protection and is generally best used for small fast repair jobs. The Hot process is a salt solution, referred to as Traditional Caustic Black. This method was adopted by larger companies for large scale. It does provide good rust resistance which is improved with the use of oil, Rust Bluing and Fume Bluing provide the best rust and corrosion resistance as the process continually converts any metal that is capable of rusting into magnetite. Treating with an oiled coating enhances the protection offered by the bluing and this process is also the only process safely used to re-blue vintage shotguns. Many double barrelled shotguns are soft soldered / silver brazed together, the higher temperatures of the other processes as well as their caustic nature will weaken the soldered joints and make the gun hazardous to use. Bluing can also be done in a furnace, for example for a sword or other item traditionally made by a blacksmith or specialist such as a weaponsmith. Blacksmith products to this day may occasionally be made from blued steel by traditional craftsmen in cultures. Bluing is most commonly used by gun manufacturers, gunsmiths, and gun owners to improve the appearance of. It was also used by machinists, who protected and beautified tools made for their own use, Bluing also helps to maintain the metal finish by resisting superficial scratching, and also helps to reduce glare to the eyes of the shooter when looking down the barrel of the gun. All blued parts still need to be oiled to prevent rust. Bluing, being a conversion coating, is not as robust against wear and corrosion resistance as plated coatings
30.
Apprenticeship
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An apprenticeship is a system of training a new generation of practitioners of a trade or profession with on-the-job training and often some accompanying study. Apprenticeship also enables practitioners to gain a license to practice in a regulated profession, Apprenticeships typically last 3 to 7 years. People who successfully complete an apprenticeship reach the journeyman or professional level of competence. In early modern usage, the clipped form prentice was common, the system of apprenticeship first developed in the later Middle Ages and came to be supervised by craft guilds and town governments. A master craftsman was entitled to employ young people as a form of labour in exchange for providing food, lodging. Most apprentices were males, but female apprentices were found in such as seamstress, tailor. Apprentices usually began at ten to fifteen years of age, in Coventry those completing seven-year apprenticeships with stuff merchants were entitled to become freemen of the city. Subsequently, governmental regulation and the licensing of technical colleges and vocational education formalized and bureaucratized the details of apprenticeship, Australian Apprenticeships encompass all apprenticeships and traineeships. They cover all sectors in Australia and are used to achieve both entry-level and career upskilling objectives. There were 470,000 Australian Apprentices in-training as at 31 March 2012, Australian Government employer and employee incentives may be applicable, while State and Territory Governments may provide public funding support for the training element of the initiative. Australian Apprenticeships combine time at work with formal training and can be full-time, part-time or school-based, Australian Apprentice and Traineeship services are dedicated to promoting retention, therefore much effort is made to match applicants with the right apprenticeship or traineeship. This is done with the aid of aptitude tests, tips, information and resources on potential apprenticeship and traineeship occupations are available in over sixty industries. The distinction between the terms apprentices and trainees lies mainly around traditional trades and the time it takes to gain a qualification, Australia also has a fairly unusual safety net in place for businesses and Australian Apprentices with its Group Training scheme. It is a safety net, because the Group Training Organisation is the employer and provides continuity of employment and it lasts two to four years – the duration varies among the 250 legally recognized apprenticeship trades. About 40 percent of all Austrian teenagers enter apprenticeship training upon completion of compulsory education and this number has been stable since the 1950s. The five most popular trades are, Retail Salesperson, Clerk, Car Mechanic, Hairdresser, there are many smaller trades with small numbers of apprentices, like EDV-Systemtechniker which is completed by fewer than 100 people a year. The Apprenticeship Leave Certificate provides the apprentice with access to two different vocational careers, the person responsible for overseeing the training inside the company is called Lehrherr or Ausbilder. An Ausbilder must prove he has the qualifications needed to educate another person
31.
Sledgehammer
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A sledgehammer is a tool with a large, flat, often metal head, attached to a lever. The size of its head allows a sledgehammer to apply more force than other hammers of similar size, along with the mallet, it shares the ability to distribute force over a wide area. This is in contrast to other types of hammers, which concentrate force in a small area. The word sledgehammer is derived from the Anglo Saxon slægan, which, in its first sense, the English words slag, slay, and slog are cognates. The handle can range from 50 centimetres to a full 1 metre long, depending on the mass of the head, the head mass is usually 1 to 3 kilograms. Modern heavy duty sledgehammers come with 10 to 20 pounds heads, sledgehammers usually require two hands and a swinging motion involving the entire torso, in contrast to smaller hammers used for driving in nails. The combination of a long swinging range, and heavy head, sledgehammers are often used in destruction work, for breaking through drywall or masonry walls. Sledgehammers are seldom used in mining operations, particularly hand steel. Sledgehammers are also used when substantial force is necessary to dislodge a trapped object, another common use is for driving fence posts into the ground. Sledgehammers are used by forces in raids on property to gain entry by force. They were and still are used by blacksmiths to shape heavy sections of iron. The British SAS counter terrorist team used sledgehammers to gain access to rooms during the 1980 Iranian Embassy Siege, however, today they use a tool called a dynamic hammer. Another iconic use of sledgehammers is for driving railroad spikes into wooden sleepers during rail construction, when the two ends of the Union Pacific railroad were joined at Promontory, Utah, Leland Stanford hammered a golden spike into a tie with a silver hammer. Sledges used to drive spikes for rails had curved heads that came down to a beak that was only one inch across. The shape meant that drivers needed to be accurate, and spot where the hit was often not much larger than a dime. Anything larger would hit the plate or the tie, the curved head kept the handle away from the rail, as the spikes were driven with the rail between the spike and the driver. These are often called spike mauls, a drilling hammer, club hammer, lump hammer, crack hammer, mini-sledge or thor hammer is a small sledgehammer whose relatively light weight and short handle allow single-handed use. It is useful for demolition work, driving masonry nails
32.
Trip hammer
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Trip hammers were usually raised by a cam and then released to fall under the force of gravity. During the Industrial Revolution the trip hammer fell out of favor and was replaced with the power hammer, often multiple hammers were powered via a set of line shafts, pulleys and belts from a centrally located power supply. In ancient China, the trip hammer evolved out of the use of the mortar and pestle, the latter was a simple device employing a lever and fulcrum, which featured a series of catches or lugs on the main revolving shaft as well. This device enabled the labor of pounding, often in the decorticating and polishing of grain, the latter book states that the legendary mythological king known as Fu Xi was the one responsible for the pestle and mortar. Afterwards the power of animals—donkeys, mules, oxen, and horses—was applied by means of machinery, with his description, it is seen that the out-of-date Chinese term for pestle and mortar would soon be replaced with the Chinese term for the water-powered trip-hammer. The Han Dynasty scholar and poet Ma Rong mentioned in one of his poems of hammers pounding in the water-echoing caves. In his Rou Xing Lun, the government official Kong Rong remarked that the invention of the hammer was an excellent example of a product created by intelligent men during his own age. There are numerous references to trip hammers during the Tang Dynasty and Song Dynasty, the recumbent hammer was found in Chinese illustrations by 1313 AD, with the publishing of Wang Zhens Nong Shu book on ancient and contemporary metallurgy in China. There were also illustrations of trip hammers in an encyclopedia of 1637, the main components for water-powered trip hammers - water wheels, cams, and hammers - were already known in Hellenistic times. Ancient cams are in evidence in early water-powered automata from the 3rd century BC and these trip-hammers were used for the pounding and hulling of grain. Apart from agricultural processing, archaeological evidence also suggests the existence of trip hammers in Roman metal working. In Ickham in Kent, a large metal hammer-head with mechanical deformations was excavated in an area where several Roman water-mills and metal waste dumps have also been traced. The widest application of trip hammers, however, seems to have occurred in Roman mining, here, the regularity and spacing of large indentations on stone anvils indicate the use of cam-operated ore stamps, much like the devices of later medieval mining. Later, Muslim engineers introduced the use of trip hammers in the production of paper, replacing the traditional Chinese mortar, water-powered and mechanised trip hammers reappeared in medieval Europe by the 12th century. Their use was described in written sources of Styria, written in 1135. Both texts mentioned the use of vertical stamp mills for ore-crushing, medieval French sources of the years 1116 and 1249 both record the use of mechanised trip hammers used in the forging of wrought iron. The well-known Renaissance artist and inventor Leonardo da Vinci often sketched trip hammers for use in forges and even file-cutting machinery, the oldest depicted European illustration of a martinet forge-hammer is perhaps the Historia de Gentibus Septentrionalibus of Olaus Magnus, dated to 1565 AD. In this woodcut image, there is the scene of three martinets and a working wood and leather bellows of the Osmund Bloomery furnace
33.
Ore
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An ore is a type of rock that contains sufficient minerals with important elements including metals that can be economically extracted from the rock. The ores are extracted from the earth through mining, they are refined to extract the valuable element. The grade or concentration of an ore mineral, or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighed against the value contained in the rock to determine what ore can be processed. Metal ores are generally oxides, sulfides, silicates, or native metals that are not commonly concentrated in the Earths crust, the ores must be processed to extract the metals of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes, the process of ore formation is called ore genesis. An ore deposit is an accumulation of ore and this is distinct from a mineral resource as defined by the mineral resource classification criteria. An ore deposit is one occurrence of a particular ore type, Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. Stratiform arkose-hosted and shale-hosted copper, typified by the Zambian copperbelt and this identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. This is because the distribution of ores is unequal and dislocated from locations of peak demand. Other, lesser, commodities do not have international clearing houses and benchmark prices and this generally makes determining the price of ores of this nature opaque and difficult. Such metals include lithium, niobium-tantalum, bismuth, antimony and rare earths, most of these commodities are also dominated by one or two major suppliers with >60% of the worlds reserves. The London Metal Exchange aims to add uranium to its list of metals on warrant, the World Bank reports that China was the top importer of ores and metals in 2005 followed by the USA and Japan. Economic geology Mineral resource classification Ore genesis Petrology Froth Flotation Extractive metallurgy DILL, the “chessboard” classification scheme of mineral deposits, Mineralogy and geology from aluminum to zirconium, Earth-Science Reviews, Volume 100, Issue 1-4, June 2010, Pages 1-420
34.
Smelting
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Smelting is a form of extractive metallurgy, its main use is to produce a base metal from its ore. This includes production of silver, iron, copper and other metals from their ores. Smelting makes use of heat and a reducing agent to decompose the ore, driving off other elements as gases or slag. The reducing agent is commonly a source of such as coke. The carbon removes oxygen from the ore, leaving behind the elemental metal, the carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide. As most ores are impure, it is necessary to use flux, such as limestone. Plants for the reduction of aluminium are also generally referred to as aluminium smelters. Smelting involves more than just melting the metal out of its ore, most ores are a chemical compound of the metal with other elements, such as oxygen, sulfur or carbon and oxygen together. To produce the metal, these compounds have to undergo a chemical reaction, smelting therefore consists of using suitable reducing substances that will combine with those oxidizing elements to free the metal. In the case of carbonates and sulfides, a process called roasting drives out the carbon or sulfur, leaving an oxide. Roasting is usually carried out in an oxidizing environment, a few practical examples, Malachite, a common ore of copper, is primarily copper carbonate hydroxide Cu22. This mineral undergoes thermal decomposition to 2CuO, CO2, and H2O in several stages between 250 °C and 350 °C, the carbon dioxide and water are expelled into the atmosphere, leaving copper oxide which can be directly reduced to copper as described in the following section titled Reduction. Galena, the most common mineral of lead, is primarily lead sulfide, the sulfide is oxidized to a sulfite which thermally decomposes into lead oxide and sulfur dioxide gas. The sulfur dioxide is expelled, and the oxide is reduced as below. Reduction is the final, high-temperature step in smelting and it is here that the oxide becomes the elemental metal. A reducing environment pulls the final oxygen atoms from the raw metal, the required temperature varies over a very large range, both in absolute terms and in terms of the melting point of the base metal. Fluxes are used in smelting for several purposes, chief among them catalyzing the desired reactions, of the seven metals known in antiquity, only gold occurred regularly in native form in the natural environment. The others – copper, lead, silver, tin, iron and mercury – occur primarily as minerals and these minerals are primarily carbonates, sulfides, or oxides of the metal, mixed with other components such as silica and alumina
35.
Carbon
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Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
36.
Alloy
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An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are defined by a metallic bonding character, an alloy may be a solid solution of metal elements or a mixture of metallic phases. Intermetallic compounds are alloys with a stoichiometry and crystal structure. Zintl phases are sometimes considered alloys depending on bond types. Alloys are used in a variety of applications. In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties, in other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Examples of alloys are steel, solder, brass, pewter, duralumin, bronze, the alloy constituents are usually measured by mass. Alloys are usually classified as substitutional or interstitial alloys, depending on the arrangement that forms the alloy. They can be classified as homogeneous, or heterogeneous or intermetallic. An alloy is a mixture of elements, which forms an impure substance that retains the characteristics of a metal. Alloys are made by mixing two or more elements, at least one of which is a metal and this is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the base, they will be soluble. The mechanical properties of alloys will often be different from those of its individual constituents. A metal that is very soft, such as aluminium, can be altered by alloying it with another soft metal. Although both metals are soft and ductile, the resulting aluminium alloy will have much greater strength. Adding a small amount of carbon to iron trades its great ductility for the greater strength of an alloy called steel. Due to its strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful. By adding chromium to steel, its resistance to corrosion can be enhanced, creating stainless steel, while adding silicon will alter its electrical characteristics, producing silicon steel
37.
Cast iron
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Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its low melting temperature. Carbon ranging from 1. 8–4 wt%, and silicon 1–3 wt% are the main alloying elements of cast iron, Iron alloys with less carbon content are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram, cast iron tends to be brittle, except for malleable cast irons. It is resistant to destruction and weakening by oxidation, the earliest cast iron artefacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, during the 15th century, cast iron became utilized for artillery in Burgundy, France, and in England during the Reformation. The first cast iron bridge was built during the 1770s by Abraham Darby III, cast iron is also used in the construction of buildings. Cast iron is made by re-melting pig iron, often along with quantities of iron, steel, limestone, carbon. Phosphorus and sulfur may be burnt out of the iron, but this also burns out the carbon. Depending on the application, carbon and silicon content are adjusted to the desired levels, other elements are then added to the melt before the final form is produced by casting. Cast iron is melted in a special type of blast furnace known as a cupola. After melting is complete, the molten cast iron is poured into a furnace or ladle. Cast irons properties are changed by adding various alloying elements, or alloyants, next to carbon, silicon is the most important alloyant because it forces carbon out of solution. A low percentage of silicon allows carbon to remain in solution forming iron carbide, a high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, nickel and copper increase strength, and machinability, but do not change the amount of graphite formed. The carbon in the form of graphite results in an iron, reduces shrinkage, lowers strength. Sulfur, largely a contaminant when present, forms iron sulfide, the problem with sulfur is that it makes molten cast iron viscous, which causes defects. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide, the manganese sulfide is lighter than the melt so it tends to float out of the melt and into the slag
38.
Slag
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Slag is the glass-like by-product left over after a desired metal has been separated from its raw ore. Slag is usually a mixture of oxides and silicon dioxide. However, slags can contain metal sulfides and elemental metals, in nature, iron, copper, lead, nickel and other metals are found in impure states called ores, often oxidized and mixed in with silicates of other metals. During smelting, when the ore is exposed to high temperatures, Slag is the collection of compounds that are removed. In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities, in this case, the slag is termed synthetic. Ferrous and non-ferrous smelting processes produce different slags, the smelting of copper and lead in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron-silicate-based slags. Slag from steel mills in ferrous smelting, on the hand, is designed to minimize iron loss and so mainly contains oxides of calcium, silicon, magnesium. Any sandy component or quartz component of the original ore automatically carries through the process as silicon dioxide. As the slag is channeled out of the furnace, water is poured over it and this rapid cooling, often from a temperature of around 2,600 °F, is the start of the granulating process. This process causes several chemical reactions to take place within the slag, the water carries the slag in its slurry format to a large agitation tank, from where it is pumped along a piping system into a number of gravel based filter beds. The filter beds then retain the slag granules, while the drains away and is returned to the system. During the Bronze Age of the Mediterranean there were a vast number of metallurgical processes in use. A slag by-product of such workings was a colorful, glassy and it was primarily blue or green and was formerly chipped away and melted down to make glassware products and jewelry. It was also ground into powder to add to glazes for use in ceramics, some of the earliest such uses for the by-products of slag have been found in ancient Egypt. Historically, the re-smelting of iron ore slag was common practice, during the early 20th century, iron ore slag was also ground to a powder and used to make agate glass, also known as slag glass. Ground granulated slag is used in concrete in combination with Portland cement as part of a blended cement. Ground granulated slag reacts with water to produce cementitious properties, concrete containing ground granulated slag develops strength over a longer period, leading to reduced permeability and better durability. Since the unit volume of Portland cement is reduced, this concrete is less vulnerable to alkali-silica, the slag can also be used to create fibers used as an insulation material called slag wool
39.
Blast furnace
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A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron, but also others such as lead or copper. The end products are usually molten metal and slag phases tapped from the bottom, the downward flow of the ore and flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process. In contrast, air furnaces are naturally aspirated, usually by the convection of hot gases in a chimney flue, according to this broad definition, bloomeries for iron, blowing houses for tin, and smelt mills for lead would be classified as blast furnaces. Blast furnaces existed in China from about 1st century AD and in the West from the High Middle Ages and they spread from the region around Namur in Wallonia in the late 15th century, being introduced to England in 1491. The fuel used in these was invariably charcoal, the successful substitution of coke for charcoal is widely attributed to Abraham Darby in 1709. The efficiency of the process was enhanced by the practice of preheating the combustion air. The oldest extant blast furnaces were built during the Han Dynasty of China in the 1st century AD. However, cast iron tools and weapons were widespread in China by the 5th century BC. These early furnaces had clay walls and used phosphorus-containing minerals as a flux, the effectiveness of the Chinese blast furnace was enhanced during this period by the engineer Du Shi, who applied the power of waterwheels to piston-bellows in forging cast iron. He suggests that early blast furnace and cast iron production evolved from furnaces used to melt bronze, certainly, though, iron was essential to military success by the time the State of Qin had unified China. Usage of the blast and cupola furnace remained widespread during the Song and Tang Dynasties and this may have happened as early as the 4th century AD. The Chinese blast furnace remained in use well until the 20th century, the backyard furnaces favoured by Mao Zedong during the Great Leap Forward were of this type. In the regions with strong traditions of metallurgy, the production actually increased during this period. In most places in the other than in China, there is no evidence of the use of the blast furnace. Instead, iron was made by reduction in bloomeries. The bloomery process was invented probably in modern-day Xinjiang or other parts of Western China by Hans or Mongols around 800 BC. Iron finds in China proper are few before bloomeries were supplanted by the blast furnace in the 5th century BC which seems to have developed independently in the southern Chinese cultural sphere, in Europe, the Greeks, Celts, Romans, and Carthaginians all used this process. Several examples have found in France, and materials found in Tunisia suggest they were used there as well as in Antioch during the Hellenistic Period
40.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
41.
Oxide
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An oxide /ˈɒksaɪd/ is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. Oxide itself is the dianion of oxygen, an O2– atom, Metal oxides thus typically contain an anion of oxygen in the oxidation state of −2. Most of the Earths crust consists of oxides, the result of elements being oxidized by the oxygen in air or in water. Hydrocarbon combustion affords the two principal carbon oxides, carbon monoxide and carbon dioxide, even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a skin of Al2O3 that protects the foil from further corrosion. Individual elements can form multiple oxides, each containing different amounts of the element. Certain elements can form many different oxides, such those of nitrogen, due to its electronegativity, oxygen forms stable chemical bonds with almost all elements to give the corresponding oxides. Noble metals are prized because they resist direct chemical combination with oxygen, two independent pathways for corrosion of elements are hydrolysis and oxidation by oxygen. The combination of water and oxygen is even more corrosive, virtually all elements burn in an atmosphere of oxygen, or an oxygen rich environment. In the presence of water and oxygen, some elements— sodium—react rapidly, even dangerously, in part for this reason, alkali and alkaline earth metals are not found in nature in their metallic, i. e. native, form. Caesium is so reactive with oxygen that it is used as a getter in vacuum tubes, the surface of most metals consists of oxides and hydroxides in the presence of air. A well-known example is aluminium foil, which is coated with a film of aluminium oxide that passivates the metal. The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodising, though solid magnesium and aluminium react slowly with oxygen at STP—they, like most metals, burn in air, generating very high temperatures. Finely grained powders of most metals can be explosive in air. Consequently, they are used in Solid-fuel rockets. In dry oxygen, iron forms iron oxide, but the formation of the hydrated ferric oxides, Fe2O3−x2x. Free oxygen production by photosynthetic bacteria some 3.5 billion years ago precipitated iron out of solution in the oceans as Fe2O3 in the important iron ore hematite. Oxides have a range of different structures, from molecules to polymeric
42.
Sulfide
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Sulfide is an inorganic anion of sulfur with the chemical formula S2−. It contributes no color to sulfide salts, as it is classified as a strong base, even dilute solutions of salts such as sodium sulfide are corrosive and can attack the skin. Sulfide is the simplest sulfur anion, the systematic names sulfanediide and sulfide, valid IUPAC names, are determined according to the substitutive and additive nomenclatures, respectively. However, the sulfide is also used in compositional IUPAC nomenclature which does not take the nature of bonding involved. Examples of such naming are selenium disulfide and titanium sulfide, which contains no sulfide ions whatsoever, hydrogen sulfide is itself an example of a non-systematic name of this nature. However, it is also a name, and the preferred IUPAC name for sulfane. Sulfide does not exist in appreciable concentrations even in highly alkaline water, the sulfide anion can assimilate a proton by recombination, S2− + H+ → SH− Because of this capture of a proton, sulfide has basic character. In aqueous solution, it has a pKb value of less than 0, in aqueous solution, most sulfide ions are neutralized. S2− + H2O ↽ − ⇀ SH− + OH− Upon treatment with an acid, sulfide converts to hydrogen sulfide. Oxidation of sulfide gives sulfur or sulfate, metal sulfides react with nonmetals including iodine, bromine, and chlorine forming sulfur and metal salts. Such inorganic sulfides typically have low solubility in water. One famous example is the bright yellow species CdS or cadmium yellow, the black tarnish formed on sterling silver is Ag2S. Such species are referred to as salts. In fact, the bonding in transition metal sulfides is highly covalent, which rise to their semiconductor properties. Several have practical applications as pigments, in cells. Aspergillus niger plays a role in the solubilization of heavy metal sulfides, many important metal ores are sulfides. Significant examples include, argentite, cinnabar, galena, molybdenite, pentlandite, realgar, and stibnite, sphalerite, and pyrite, dissolved free sulfides are very aggressive species for the corrosion of many metals such as steel, stainless steel, and copper. Sulfides present in solution are responsible for stress corrosion cracking of steel
43.
Malleable iron
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Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment, the structure as first cast is transformed into the malleable form. Carbon agglomerates into small roughly spherical aggregates of graphite leaving a matrix of ferrite or pearlite according to the heat treatment used. Three basic types of iron are recognized within the casting industry, blackheart malleable iron, whiteheart malleable iron. Malleable iron was used as early as the 4th century BCE, by the Tang Dynasty, the use of malleable iron in China waned, although there are malleable iron artifacts dating to the 9th century. Malleable iron is mentioned in England in a patent dating to the 1670s, réaumur conducted extensive research on malleable iron in 1720. He discovered that iron castings which were too hard to be worked could be softened by packing them into iron ore or hammer slag, creating malleable iron began in the United States in 1826 when Seth Boyden started a foundry for the production of harness hardware and other small castings. Like similar irons with the carbon formed into spherical or nodular shapes, incorrectly considered by some to be an old or dead material, malleable iron still has a legitimate place in the design engineers toolbox. Malleable iron is a choice for small castings or castings with thin cross sections. Other nodular irons produced with graphite in the shape can be difficult to produce in these applications. Malleable iron also exhibits better fracture toughness properties in low temperature environments than other nodular irons, the ductile to brittle behavior transformation temperature is lower than many other ductile iron alloys. Thicker sections of a casting will cool slowly, allowing some primary graphite to form and this graphite forms random flake-like structures and will not transform to carbide during heat treatment. When stress is applied to such a casting in application, the strength will be lower than expected for white iron. Such iron is said to have a mottled appearance, some countermeasures can be applied to enhance the formation of the all white structure, but malleable iron foundries often avoid producing heavy sections. After the casting and heat treatment processes, malleable iron can be shaped through cold working and this is possible due to malleable irons desirable property of being less strain rate sensitive than other materials. It is often used for small castings requiring good tensile strength, uses include electrical fittings, hand tools, pipe fittings, washers, brackets, fence fittings, power line hardware, farm equipment, mining hardware, and machine parts
44.
Wayland the Smith
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In Norse mythology, Wayland the Smith is a legendary master blacksmith, described by Jessie Weston as the weird and malicious craftsman, Weyland. In Old Norse sources, Völundr appears in Völundarkviða, a poem in the Poetic Edda, and in Þiðrekssaga, in Old English sources, he appears in Deor, Waldere and in Beowulf and the legend is depicted on the Franks Casket. He is mentioned in the German poems about Theoderic the Great as the Father of Witige, according to Völundarkviða, the king of the Sami people had three sons, Völundr and his two brothers Egil and Slagfiðr. In one version of the myth, the three lived with three Valkyries, Ölrún, Hervör alvitr and Hlaðguðr svanhvít. After nine years, the Valkyries left their lovers, Egil and Slagfiðr followed, never to return. In another version, Völundr married the swan maiden Hervör, and they had a son, Heime, in both versions, his love left him with a ring. In the former myth, he forged seven hundred duplicates of this ring, later, King Niðhad captured Völundr in his sleep in Nerike and ordered him hamstrung and imprisoned on the island of Sævarstöð. There Völundr was forced to forge items for the king, völundrs wifes ring was given to the kings daughter, Böðvildr. In revenge, Völundr killed the kings sons when they visited him in secret, fashioned goblets from their skulls, jewels from their eyes, and he sent the goblets to the king, the jewels to the queen and the brooch to the kings daughter. When Bodvild took her ring to Wayland for mending, he took the ring and raped her and he then escaped, using wings he made. Völundr made the magic sword Gram and the ring that Thorsten retrieved. The Old English poem Deor, which recounts the famous sufferings of various figures before turning to those of Deor, its author, begins with Welund, Welund tasted misery among snakes. The stout-hearted hero endured troubles had sorrow and longing as his companions cruelty cold as winter - he often found woe Once Nithad laid restraints on him and that went by, so can this. That went by, so can this, Weland had fashioned the mail shirt worn by Beowulf according to lines 450–455 of the epic poem of the same name, No need then to lament for long or lay out my body. If the battle takes me, send back this breast-webbing that Weland fashioned and Hrethel gave me, fate goes ever as fate must. The Franks Casket is one of a number of other Old English references to Wayland, whose story was well known and popular. Below the forge is the body of Niðhads son, who Wayland has killed, making a goblet from his skull. With his other hand Wayland offers the goblet, containing drugged beer, to Böðvildr, Niðhads daughter, another female figure is shown in the centre, perhaps Waylands helper, or Bodvild again
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