1.
Solder
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Solder is a fusible metal alloy used to create a permanent bond between metal workpieces. The word solder comes from the Middle English word soudur, via Old French solduree and soulder, from the Latin solidare, meaning to make solid. In fact, solder must be melted in order to adhere to and connect the pieces together, whenever possible, the solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder that is intended for use in making connections between electronic components also usually has favorable electrical characteristics. Soft solder typically has a melting point range of 90 to 450 °C, and is used in electronics, plumbing. Manual soldering uses an iron or soldering gun. Alloys that melt between 180 and 190 °C are the most commonly used, soldering performed using alloys with a melting point above 450 °C is called hard soldering, silver soldering, or brazing. In specific proportions, some alloys can become eutectic — that is, non-eutectic alloys have markedly different solidus and liquidus temperatures, and within that range they exist as a paste of solid particles in a melt of the lower-melting phase. In electrical work, if the joint is disturbed in the pasty state before it has solidified totally, for electrical and electronics work, solder wire is available in a range of thicknesses for hand-soldering, and with cores containing flux. It is also available as a paste or as a preformed foil shaped to match the workpiece, alloys of lead and tin were commonly used in the past, and are still available, they are particularly convenient for hand-soldering. Lead-free solders have been increasing in use due to regulatory requirements plus the health and they are almost exclusively used today in consumer electronics. Plumbers often use bars of solder, much thicker than the used for electrical applications. Jewelers often use solder in thin sheets, which cut into snippets. In the US, manufacturers may receive tax benefits by reducing the use of lead-based solder, lead-free solders in commercial use may contain tin, copper, silver, bismuth, indium, zinc, antimony, and traces of other metals. Most lead-free replacements for conventional 60/40 and 63/37 Sn-Pb solder have melting points from 5 to 20 °C higher and it may be desirable to use minor modification of the solder pots used in wave-soldering, to reduce maintenance cost due to increased tin-scavenging of high-tin solder. Lead-free solder may be desirable for critical applications, such as aerospace and medical projects. Tin-Silver-Copper solders are used by two-thirds of Japanese manufacturers for reflow and wave soldering, tin-based solders readily dissolve gold, forming brittle intermetallics, for Sn-Pb alloys the critical concentration of gold to embrittle the joint is about 4%. Indium-rich solders are more suitable for soldering thicker gold layer as the rate of gold in indium is much slower
2.
Thermocouple
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A thermocouple is an electrical device consisting of two dissimilar conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the effect. Thermocouples are a widely used type of temperature sensor, commercial thermocouples are inexpensive, interchangeable, are supplied with standard connectors, and can measure a wide range of temperatures. In contrast to most other methods of measurement, thermocouples are self powered. The main limitation with thermocouples is accuracy, system errors of less than one degree Celsius can be difficult to achieve, Thermocouples are widely used in science and industry, applications include temperature measurement for kilns, gas turbine exhaust, diesel engines, and other industrial processes. Thermocouples are also used in homes, offices and businesses as the sensors in thermostats. At the time Seebeck referred to this as thermo-magnetism, the magnetic field he observed was later shown to be due to thermo-electric current. In practical use, the voltage generated at a junction of two different types of wire is what is of interest as this can be used to measure temperature at very high. The magnitude of the voltage depends on the types of wire used, generally, the voltage is in the microvolt range and care must be taken to obtain a usable measurement. Although current flows very little, power can be generated by a thermocouple junction. Power generation using multiple thermocouples, as in a thermopile, is common, the standard configuration for thermocouple usage is shown in the figure. Briefly, the desired temperature Tsense is obtained using three inputs—the characteristic function E of the thermocouple, the measured voltage V, and the reference junctions temperature Tref, the solution to the equation E = V + E yields Tsense. These details are hidden from the user since the reference junction block, voltmeter. The Seebeck effect refers to an electromotive force whenever there is a gradient in a conductive material. The standard measurement configuration shown in the figure, shows four temperature regions and thus four voltage contributions, Change from T m e t e r to T r e f, Change from T r e f to T s e n s e, in the alumel wire. Change from T s e n s e to T r e f, Change from T r e f to T m e t e r, in the upper copper wire. The first and fourth contributions cancel out exactly, because these regions involve the same temperature change, as a result, T m e t e r does not influence the measured voltage. The second and third contributions do not cancel, as they involve different materials, an integral does not need to be performed for every temperature measurement
3.
General American
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Due to General American accents being widespread throughout the United States, they are sometimes, though controversially, classified as Standard American English. The precise definition and usefulness of General American continues to be debated, the term General American was first disseminated by American English scholar George Philip Krapp, who, in 1925, described it as an American type of speech that was Western but not local in character. In 1930, American linguist John Samuel Kenyon, who popularized the term, considered it equivalent to the speech of the North, or Northern American. By 1982, according to British phonetician John C, wells, two-thirds of the American population spoke with a General American accent. Accents that have never been included, even since the popularization in the 1930s, are the regional accents of Eastern New England, New York City. English-language scholar William A. Kretzchmar, Jr, no historical justification for this term exists, and neither do present circumstances support its use. T implies that there is some state of American English from which other varieties deviate. On the contrary, can best be characterized as what is left over after speakers suppress the regional and social features that have risen to salience, from place to place, and even from speaker to speaker. The term Standard North American English, in an effort to incorporate Canadian speakers under the accent continuum, has also very recently suggested by sociolinguist Charles Boberg. Ironically, Ohio, far from being an area of non-regional English, is now a crossroads for at least four distinct regional accents. General American is commonly promoted as preferable to other regional accents, in the United States, instructional classes promising accent reduction, accent modification, or accent neutralization usually attempt to teach speech General American accent patterns. /ʍ/ is often analyzed as a consonant cluster of /hw/, rhoticity, General American accents are firmly rhotic, pronouncing the r sound in all environments, including after vowels, such as in pearl, car, and court. Americans often realize the phoneme as postalveolar, as in most varieties of English, t-glottalization, /t/ is pronounced as a glottal stop before a consonant, as in button, and sometimes at the end of a word, as in what. Flapping, /t/ and /d/ become a flap, written, between vowels or liquids, as in water, party, model, and what is it. L-velarization, The distinction between an l and a dark l in the standard English of England is mostly absent in General American. Instead, all l sounds are pronounced more or less dark, some speakers also vocalize /l/ to when it appears before /f v/. The following charts present the vowels that these three dialects encompass as a perceived General American sound system and this sound may be narrowly transcribed as, or, based on a specific dialect, variously as or. This phenomenon is called /æ/-tensing in phonological discourse, father–bother merger, Nearly all American accents merge the broad a in words like spa and ah with the short o of words like spot and odd, therefore, con and khan are homophones in General American
4.
Received Pronunciation
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Peter Trudgill estimated in 1974 that 3% of people in Britain were RP speakers, but this rough estimate has been questioned by the phonetician J. Windsor Lewis. Since the 1960s, a greater permissiveness towards regional English varieties has taken hold in education, an individual using RP will typically speak Standard English, although the converse or inverse is not necessarily true. The standard language may be pronounced with an accent and the contrapositive is usually correct. It is very unlikely that someone speaking RP would use it to speak a regional dialect, the introduction of the term Received Pronunciation is usually credited to Daniel Jones. However, the term had actually been used earlier by Alexander Ellis in 1869 and P. S. Du Ponceau in 1818 According to Fowlers Modern English Usage. The word received conveys its meaning of accepted or approved. RP is often believed to be based on the accents of southern England and this was the most populated and most prosperous area of England during the 14th and 15th centuries. By the end of the 15th century, Standard English was established in the City of London, some linguists have used the term RP while expressing reservations about its suitability. Other writers have used the name BBC Pronunciation. He used the term General British in his 1970s publication of A Concise Pronouncing Dictionary of American and British English, Received Pronunciation has sometimes been called Oxford English, as it used to be the accent of most members of the University of Oxford. The Handbook of the International Phonetic Association uses the name Standard Southern British, page 4 reads, Standard Southern British is the modern equivalent of what has been called Received Pronunciation. It is an accent of the south east of England which operates as a prestige norm there and in parts of the British Isles. Faced with the difficulty of defining RP, many writers have tried to distinguish between different sub-varieties, later editions use the terms General, Refined and Regional. Wells refers to mainstream RP and U-RP, he suggests that Gimsons categories of Conservative and Advanced RP referred to the U-RP of the old, however, Wells stated, It is difficult to separate stereotype from reality with U-RP. Upton distinguishes between RP, Traditional RP, and an older version which he identifies with Cruttendens Refined RP. An article on the website of the British Library refers to Conservative, Mainstream, the modern style of RP is an accent often taught to non-native speakers learning British English. Non-RP Britons abroad may modify their pronunciation to something closer to Received Pronunciation to be understood by people unfamiliar with the diversity of British accents. They may also modify their vocabulary and grammar to be closer to those of Standard English for the same reason
5.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
6.
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
7.
Brazing
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The filler metal flows into the gap between close-fitting parts by capillary action. The filler metal is slightly above its melting temperature while protected by a suitable atmosphere. It then flows over the metal and is then cooled to join the work pieces together. It is similar to soldering, except for the use of higher temperatures, a major advantage of brazing is the ability to join the same or different metals with considerable strength. High-quality brazed joints require that parts be closely fitted, and the base metals exceptionally clean, in most cases, joint clearances of 0.03 to 0.08 mm are recommended for the best capillary action and joint strength. However, in some brazing operations it is not uncommon to have joint clearances around 0.6 mm, cleanliness of the brazing surfaces is also important, as any contamination can cause poor wetting. The two main methods for cleaning parts, prior to brazing, are cleaning and abrasive or mechanical cleaning. In the case of mechanical cleaning, it is important to maintain the surface roughness as wetting on a rough surface occurs much more readily than on a smooth surface of the same geometry. Another consideration is the effect of temperature and time on the quality of brazed joints, as the temperature of the braze alloy is increased, the alloying and wetting action of the filler metal increases as well. In general, the brazing temperature selected must be above the point of the filler metal. However, several factors influence the joint designers temperature selection, the effect of time on the brazed joint primarily affects the extent to which these effects are present. In general, however, most production processes are selected to minimize brazing time and this is not always the case, however, since in some non-production settings, time and cost are secondary to other joint attributes. Unless brazing operations are contained within an inert or reducing atmosphere environment, the flux also serves the purpose of cleaning any contamination left on the brazing surfaces. Flux can be applied in any number of forms including flux paste, liquid, flux can also be applied using brazing rods with a coating of flux, or a flux core. In either case, the flows into the joint when applied to the heated joint and is displaced by the molten filler metal entering the joint. Excess flux should be removed when the cycle is completed because flux left in the joint can lead to corrosion, impede joint inspection, phosphorus-containing brazing alloys can be self-fluxing when joining copper to copper. Fluxes are generally selected based on their performance on particular base metals, to be effective, the flux must be chemically compatible with both the base metal and the filler metal being used. Self-fluxing phosphorus filler alloys produce brittle phosphides if used on iron or nickel, as a general rule, longer brazing cycles should use less active fluxes than short brazing operations
8.
Lead
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Lead is a chemical element with atomic number 82 and symbol Pb. When freshly cut, it is bluish-white, it tarnishes to a dull gray upon exposure to air and it is a soft, malleable, and heavy metal with a density exceeding that of most common materials. Lead has the second-highest atomic number of the stable elements. Lead is a relatively unreactive post-transition metal and its weak metallic character is illustrated by its amphoteric nature and tendency to form covalent bonds. Compounds of lead are found in the +2 oxidation state. Exceptions are mostly limited to organolead compounds, like the lighter members of the group, lead exhibits a tendency to bond to itself, it can form chains, rings, and polyhedral structures. Lead is easily extracted from its ores and was known to people in Western Asia. A principal ore of lead, galena, often bears silver, Lead production declined after the fall of Rome and did not reach comparable levels again until the Industrial Revolution. Nowadays, global production of lead is about ten million tonnes annually, Lead has several properties that make it useful, high density, low melting point, ductility, and relative inertness to oxidation. In the late 19th century, lead was recognized as poisonous, Lead is a neurotoxin that accumulates in soft tissues and bones, damaging the nervous system and causing brain disorders and, in mammals, blood disorders. A lead atom has 82 electrons, arranged in a configuration of 4f145d106s26p2. The combined first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, leads upper neighbor in group 14. This is unusual since ionization energies generally fall going down a group as an elements outer electrons become more distant from the nucleus, the similarity is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, and the relatively small radii of the elements after hafnium. The contraction is due to shielding of the nucleus by the lanthanide 4f electrons. The combined first four ionization energies of lead exceed those of tin, for this reason lead, unlike tin, mostly forms compounds in which it has an oxidation state of +2, rather than +4. Relativistic effects, which become particularly prominent at the bottom of the periodic table, as a result, the 6s electrons of lead become reluctant to participate in bonding, a phenomenon called the inert pair effect. A related outcome is that the distance between nearest atoms in crystalline lead is unusually long, the lighter group 14 elements form stable or metastable allotropes having the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals
9.
Stained glass
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The term stained glass can refer to coloured glass as a material or to works created from it. Throughout its thousand-year history, the term has been applied almost exclusively to the windows of churches, mosques, although traditionally made in flat panels and used as windows, the creations of modern stained glass artists also include three-dimensional structures and sculpture. Modern vernacular usage has extended the term stained glass to include domestic leadlight. As a material stained glass is glass that has been coloured by adding metallic salts during its manufacture. The coloured glass is crafted into stained glass windows in which pieces of glass are arranged to form patterns or pictures, held together by strips of lead. Painted details and yellow stain are used to enhance the design. The term stained glass is applied to windows in which the colours have been painted onto the glass. Stained glass, as an art and a craft, requires the artistic skill to conceive an appropriate and workable design, and the engineering skills to assemble the piece. A window must fit snugly into the space for which it is made, must resist wind and rain, Many large windows have withstood the test of time and remained substantially intact since the late Middle Ages. In Western Europe they constitute the form of pictorial art to have survived. In this context, the purpose of a glass window is not to allow those within a building to see the world outside or even primarily to admit light. For this reason stained glass windows have been described as illuminated wall decorations, Stained glass is still popular today, but often referred to as art glass. It is prevalent in luxury homes, commercial buildings, and places of worship, artists and companies are contracted to create beautiful art glass ranging from domes, windows, backsplashes, etc. During the late Medieval period, glass factories were set up there was a ready supply of silica. Silica requires very high heat to become molten, something not all glass factories were able to achieve, such materials as potash, soda, and lead can be added to lower the melting temperature. Other substances, such as lime, are added to rebuild the weakened network, Glass is coloured by adding metallic oxide powders or finely divided metals while it is in a molten state. Copper oxides produce green or bluish green, cobalt makes deep blue, much modern red glass is produced using copper, which is less expensive than gold and gives a brighter, more vermilion shade of red. Glass coloured while in the pot in the furnace is known as pot metal glass
10.
Flashing (weatherproofing)
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Flashing refers to thin pieces of impervious material installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier system. The origin of flash and flashing are uncertain, but may come from the Middle English verb flasshen, to sprinkle, splash, related to flask. Strips of lead used for flashing an edge were sometimes called an apron, the up-hill side of a chimney may have a small gable-like assembly called a cricket with cricket flashing or on narrow chimneys with no cricket a back flashing or back pan flashing. Flashing may be let into a groove in a wall or chimney called a reglet, in builders books, by 1832 Loudons An Encyclopædia of Cottage, Farm, and Villa Architecture and Furniture. Gives instruction on installing lead flashing and 1875 Notes on Building Construction gives detailed instruction and is illustrated with methods still used today. Flashing may be exposed or concealed, exposed flashing is usually of a sheet metal and concealed flashing may be metal or a flexible, adhesive backed, material particularly around wall penetrations such as window and door openings. In earlier days, birch bark was used as a flashing material. Most flashing materials today are metal, plastic, rubber, or impregnated paper, an important type of potential chemical reaction between metal flashing materials is galvanic corrosion. Copper and lead cannot be used in contact with or even above aluminum, zinc, also, Aluminum and zinc flashing cannot be used in contact with pressure treated wood due to rapid corrosion. Aluminum is also damaged by wet mortar and wet plaster, salt spray in coastal areas may accelerate corrosion. So stainless steel, copper, or coated aluminum are recommended flashing materials near salt water, types of flexible flashing products are rubberized asphalt, butyl rubber, polyvinylidene fluoride, and acrylic. No flexible flashing material is designed to remain exposed over the term as are metal flashing materials. Adhesive backed materials are convenient during installation, but such adhesives are not intended for long-term water-resistance and this enables a roof to be built without weak points. Since flashing is expensive to replace if it fails, copper’s long life is a major cost advantage, cold rolled copper is recommended for most flashing applications. This material offers more resistance than soft copper to the stresses of expansion and contraction, soft copper can be specified where extreme forming is required, such as in complicated roof shapes. Thermal movement in flashings is prevented or is permitted only at predetermined locations, soft zinc is a newer, proprietary flashing material. It is a malleable material, making it useful for complex roofing connections. It provides normal soft soldering capabilities and delivers easy folding, soft zinc is said to be an environmentally friendly replacement for lead flashing, like lead, it is recyclable, while avoiding lead-contaminated runoff
11.
Plumbing
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Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, heating and cooling, waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes, in the developed world, plumbing infrastructure is critical to public health and sanitation. Boilermakers and pipefitters are not plumbers, although they work with piping as part of their trade, standardized earthen plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 B. C. The Romans used lead pipe inscriptions to prevent water theft, Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes. With the Fall of Rome both water supply and sanitation stagnated—or regressed—for well over 1,000 years, improvement was very slow, with little effective progress made until the growth of modern densely populated cities in the 1800s. During this period, public authorities began pressing for better waste disposal systems to be installed. Earlier, the disposal system had merely consisted of collecting waste. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches, most large cities today pipe solid wastes to sewage treatment plants in order to separate and partially purify the water, before emptying into streams or other bodies of water. For potable water use, galvanized iron piping was commonplace in the United States from the late 1800s until around 1960, after that period, copper piping took over, first soft copper with flared fittings, then with rigid copper tubing utilizing soldered fittings. The use of lead for potable water declined sharply after World War II because of increased awareness of the dangers of lead poisoning, at this time, copper piping was introduced as a better and safer alternative to lead pipes. e. Heating and cooling systems utilizing water to transport thermal energy, as in district heating systems, a water pipe is a pipe or tube, frequently made of plastic or metal, that carries pressurized and treated fresh water to a building, as well as inside the building. For many centuries, lead was the material for water pipes. This was a source of lead-related health problems in the years before the hazards of ingesting lead were fully understood, among these were stillbirths. Lead water pipes were still used in the early 20th century. In addition, lead-tin alloy solder was commonly used to join copper pipes, despite the Romans common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, what often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water. This was a result of lead being used in cookware and as an additive to processed food and drink
12.
Rain gutter
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A rain gutter or surface water collection channel is a component of water discharge system for a building. Water from a pitched roof flows down into a valley gutter, an eaves gutter is also known as an eavestrough, eaves channel, dripster, guttering or simply as a gutter. The word gutter derives from Latin gutta, meaning a drop, guttering in its earliest form consisted of lined wooden or stone troughs. Lead was a liner and is still used in pitched valley gutters. Many materials have been used to make guttering, cast iron, asbestos cement, UPVC, cast, gutters prevent water ingress into the fabric of the building by channelling the rainwater away from the exterior of the walls and their foundations. Water running down the walls causes dampness in the rooms and provides a favourable environment for growth of mould. A rain gutter may be a, Roof integral trough along the edge of the roof slope which is fashioned from the roof covering and flashing materials. Discrete trough of metal, or other material that is suspended beyond the roof edge, wall integral structure beneath the roof edge, traditionally constructed of masonry, fashioned as the crowning element of a wall. A roof must be designed with a fall to allow the rainwater to discharge. The water drains into a gutter that is fed into a downpipe, a flat roof will have a watertight surface with a fall of 1 in 60, or 1 in the case of lead. They can drain internally or to a gutter, which has a minimum 1 in 360 fall towards the downpipe. The pitch of a roof is determined by the construction material of the covering. For slate this will be at 25%, for machine made tiles it will be 35%, water falls towards a parapet gutter, a valley gutter or an eaves gutter. When two pitched roofs meet at an angle, they form a pitched valley gutter, the join is sealed with valley flashing. Parapet gutters and valley gutters discharge into internal rainwater pipes or directly into external down pipes at the end of the run, the capacity of the gutter is a significant design consideration. The area of the roof is calculated and this is multiplied by rainfall which is assumed to be 0.0208 and this gives a required discharge outfall capacity.022 l/s/m²- while one in Cumbria delivers 0.014 l/s/m². Eaves gutters can be made from a variety of such as cast iron, lead, zinc, galvanised steel, painted steel, copper, painted aluminium, PVC and occasionally from concrete, stone. Water collected by a rain gutter is fed, usually via a downpipe, alternatively it would connect via a gulley with 50mm water seal to a combined drain
13.
Radiator
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Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, despite the name, most radiators transfer the bulk of their heat via convection instead of thermal radiation, though the term convector is used more narrowly, see radiation and convection, below. The Roman hypocaust, a type of radiator for building heating, was described in 15 AD. The heating radiator was invented by Franz San Galli, a Prussian-born Russian businessman living in St. Petersburg, in practice, the term radiator refers to any of a number of devices in which a liquid circulates through exposed pipes. The term convector refers to a class of devices in which the source of heat is not directly exposed, radiators are commonly used to heat buildings. To cool down the engine, a coolant is passed through the engine block, the hot coolant is then fed into the inlet tank of the radiator, from which it is distributed across the radiator core through tubes to another tank on the opposite end of the radiator. The fins then release the heat to the ambient air, fins are used to greatly increase the contact surface of the tubes to the air, thus increasing the exchange efficiency. The cooled coolant is fed back to the engine, and the cycle repeats, normally, the radiator does not reduce the temperature of the coolant back to ambient air temperature, but it is still sufficiently cooled to keep the engine from overheating. This coolant is usually water-based, with the addition of glycols to prevent freezing, however, the coolant may also be an oil. The first engines used thermosiphons to circulate the coolant, today, however, all, up to the 1980s, radiator cores were often made of copper and brass. Starting in the 1970s, use of aluminium increased, eventually taking over the vast majority of vehicular radiator applications, the main inducements for aluminium are reduced weight and cost. However, the cooling properties of Copper-Brass over Aluminium makes it preferential for high performance vehicles or stationary applications. In particular MW-class installations, copper-brass constructions are still dominant, since air has a lower heat capacity and density than liquid coolants, a fairly large volume flow rate must be blown through the radiator core to capture the heat from the coolant. Radiators often have one or more fans that blow air through the radiator, to save fan power consumption in vehicles, radiators are often behind the grille at the front end of a vehicle. Ram air can give a portion or all of the cooling air flow when the coolant temperature remains below the systems designed maximum temperature. As electronic devices become smaller, the problem of dispersing waste heat becomes more difficult, tiny radiators known as heat sinks are used to convey heat from the electronic components into a cooling air stream. Radiators are found as components of some spacecraft and these radiators work by radiating heat energy away as light because in the vacuum of space neither convection nor conduction can work to transfer heat away. On the International Space Station these can be seen clearly as large white panels attached to the main truss and they can be found on both manned and unmanned craft
14.
Jewelry
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Jewellery or jewelry consists of small decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, and bracelets. Jewellery may be attached to the body or the clothes, for many centuries metal, often combined with gemstones, has been the normal material for jewellery, but other materials such as shells and other plant materials may be used. It is one of the oldest type of archaeological artefact – with 100, historically, the most widespread influence on jewellery in terms of design and style have come from Asia. Jewellery may be made from a range of materials. Gemstones and similar such as amber and coral, precious metals, beads, and shells have been widely used. In most cultures jewellery can be understood as a symbol, for its material properties, its patterns. Jewellery has been made to nearly every body part, from hairpins to toe rings. The word jewellery itself is derived from the jewel, which was anglicised from the Old French jouel. In British English, Indian English, New Zealand English, Hiberno-English, Australian English, both are used in Canadian English, though jewelry prevails by a two to one margin. Numerous cultures store wedding dowries in the form of jewellery or make jewellery as a means to store or display coins, alternatively, jewellery has been used as a currency or trade good, an example being the use of slave beads. Many items of jewellery, such as brooches and buckles, originated as functional items. Jewellery can also symbolise group membership or status, wearing of amulets and devotional medals to provide protection or ward off evil is common in some cultures. These may take the form of symbols, stones, plants, animals, body parts, in creating jewellery, gemstones, coins, or other precious items are often used, and they are typically set into precious metals. Alloys of nearly every metal known have been encountered in jewellery, bronze, for example, was common in Roman times. Modern fine jewellery usually includes gold, white gold, platinum, palladium, titanium, most contemporary gold jewellery is made of an alloy of gold, the purity of which is stated in karats, indicated by a number followed by the letter K. American gold jewellery must be of at least 10K purity, many whimsical fashions were introduced in the extravagant eighteenth century. Cameos that were used in connection with jewellery were the attractive trinkets along with many of the objects such as brooches, ear-rings. Some of the necklets were made of pieces joined with the gold chains were in and bracelets were also made sometimes to match the necklet
15.
Came
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A came is a divider bar used between small pieces of glass to make a larger glazing panel. There are two kinds of came, the H-shaped sections that two pieces together and the U-shaped sections that are used for the borders. Cames are mostly made of lead, zinc, copper, brass or brass-capped lead, of the metal strips, lead is softer and more flexible, making it easier to cut and bend. The harder metals are used to work with slightly curved lines and pieces that require greater structural support and they can also be used as border came, once again for stability and support. Came serves three purposes, it joins the pieces of glass, forms the lines within the glasswork and provides the metal to be soldered, came comes in varying face sizes and shapes. They can be round, flat or colonial shaped strips and they can also be narrow or have wide faces. It has either a flat or rounded profile and its width is the measurement given when a came size is listed, the channel runs the length of the came. H-shaped came has 2 back-to-back channels that hold adjoining glass pieces in position on the interior of a glass panel. It can also be used as a border came in certain situations, U-shaped came has only one channel and is used as a border around the perimeter of panels. The heart is the part of the came that the glass pieces rest against inside the channel, the width of lead came pattern lines is usually 1/16 inch and allows for the thickness of the cames heart to fit between the adjoining pieces of glass. The width and depth of the used to assemble the piece affect the pattern for cutting glass. Border cames are U-channel cames that are used on the edges of works. The selection of the metal of the came may vary depending upon the work, for instance, zinc may be a solid selection for free-hanging panels, because it is rigid, but lightweight. Architectural panels, on the hand, are often enclosed in framing. Bumpers, or lead spacers, are pieces of cut came strips that are left over and they can be used temporarily in the glasswork process to hold together two pieces of glass to estimate the spacing of the finished project
16.
Came glasswork
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Came glasswork is the process of joining cut pieces of art glass through the use of came strips or foil into picturesque designs in a framework of soldered metal. Finished products can include a range of glasswork, including stained glass. Came is made of different metals, such as lead, zinc, brass, the metal came selected generally depends upon the size, complexity and weight of the project. As an alternative to came, copper foil may be used, for small, came glasswork includes assembling pieces of cut and possibly painted glass using came sections. The joints where the meet are soldered to bind the sections. When all of the pieces have been put within came. The work may be made waterproof by forcing a soft oily cement or mastic between the glass and the cames, a form of embellishment and gilding, such as Angel gilding and Eglomise, may be added to finish the piece. Works may need to be reinforced, like large pieces or ones that will be exposed to the outdoor elements, bars of steel or steel rebar may be attached to the back of finished works as reinforcement. Theophilus Presbyter, the first to write about joining art glass using the technique in the book De Divers Artibus. Theophilus was a Benedictine Monk who was a glass and pigment worker who practiced in the late 11th and early 12th centuries. See also the articles on Leadlight history and Medieval stained glass history Materials to complete a project may include the pattern, cut glass, came, wood trim, solder. Additional supplies include newspaper, cutter oil, a board, masking tape, flux. Lead came is often supplied in lengths of 2 m and in widths of differing sizes and it also comes in flat or domed profiles. Brass and copper have been used to bring a copper or golden hue to the works, generally, though, they were used only for windows between about 1890 and 1920. Both metals were often alternatives to zinc for Frank Lloyd Wright designed windows, brass-capped lead is another type of came used for glasswork projects. The traditional method of creating camework glass uses lead came, which ages into a dark blue-gray patina, in comparison to other came metal strips, like brass, copper and zinc, lead is softer and more flexible, making it easier to cut and bend. A downside is that the projects may be prone to sagging due to leads softness. This can be mitigated somewhat by stretching the lead to make it more rigid before it is used, special precautions should be taken when working with this metal came to avoid to lead contamination
17.
Electrical wiring
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Electrical wiring is commonly understood to be an electrical installation for operation by end users within a building, an engineered structure or a designated outdoor location. It includes the cabling and associated such as switches, distribution boards, sockets and light fittings. Such wiring is subject to safety standards for design and installation. Associated circuit protection, control and distribution devices within a buildings wiring system are subject to voltage, current, the International Electrotechnical Commission is attempting to harmonise wiring standards amongst member countries, but significant variations in design and installation requirements still exist. Wiring installation codes and regulations are intended to protect people and property from electrical shock and they are usually based on a model code produced by a national or international standards organisation, such as the IEC. The standard is mandatory in both New Zealand and Australia, therefore, all electrical work covered by the standard must comply, in European countries, an attempt has been made to harmonise national wiring standards in an IEC standard, IEC60364 Electrical Installations for Buildings. Hence national standards follow a system of sections and chapters. However, this standard is not written in language that it can readily be adopted as a national wiring code. Neither is it designed for use by electrical tradesmen and inspectors for testing compliance with national wiring standards. In Germany, DKE is the responsible for the promulgation of electrical standards. DIN VDE0100 is the German wiring regulations document harmonised with IEC60364, the first electrical codes in the United States originated in New York in 1881 to regulate installations of electric lighting. Since 1897 the US National Fire Protection Association, a private non-profit association formed by insurance companies, has published the National Electrical Code, States, counties or cities often include the NEC in their local building codes by reference along with local differences. The NEC is modified every three years and it is a consensus code considering suggestions from interested parties. The proposals are studied by committees of engineers, tradesmen, manufacturer representatives, fire fighters, since 1927, the Canadian Standards Association has produced the Canadian Safety Standard for Electrical Installations, which is the basis for provincial electrical codes. The Canadian code reprints Chapter 13 of IEC60364, but there are no numerical criteria listed in that chapter to assess the adequacy of any electrical installation. Although the US and Canadian national standards deal with the physical phenomena and broadly similar objectives. As part of the North American Free Trade Agreement program, US and Canadian standards are slowly converging toward each other, the 17th edition includes new sections for microgeneration and solar photovoltaic systems. The first edition was published in 1882, to enable wires to be easily and safely identified, all common wiring safety codes mandate a colour scheme for the insulation on power conductors
18.
Electronic component
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An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components have a number of electrical terminals or leads and these leads connect to create an electronic circuit with a particular function. The following list of electronic components focuses on the version of these components. Components can be classified as passive, active, or electromechanic, the strict physics definition treats passive components as ones that cannot supply energy themselves, whereas a battery would be seen as an active component since it truly acts as a source of energy. However, electronic engineers who perform circuit analysis use a more restrictive definition of passivity, then, the analysis only concerns the AC circuit, an abstraction that ignores DC voltages and currents present in the real-life circuit. This fiction, for instance, lets us view an oscillator as producing energy even though in reality the oscillator consumes even more energy from a DC power supply, active components include amplifying components such as transistors, triode vacuum tubes, and tunnel diodes. Passive components cant introduce net energy into the circuit and they also cant rely on a source of power, except for what is available from the circuit they are connected to. As a consequence they cant amplify, although they may increase a voltage or current, passive components include two-terminal components such as resistors, capacitors, inductors, and transformers. In contrast, active components generally lack that property, conduct electricity easily in one direction, among more specific behaviors. A transistor is a device used to amplify and switch electronic signals. Resistors, capacitors, inductors, and transformers are all considered passive devices, pass current in proportion to voltage and oppose current. They are used for filtering power supply lines, tuning resonant circuits, transducers generate physical effects when driven by an electrical signal, or vice versa. Sensors are transducers that react to environmental conditions by changing their electrical properties or generating an electrical signal, the transducers listed here are single electronic components, and are passive. Only the most common ones are listed here, reference designators are applied to the symbols to identify the component
19.
Printed circuit board
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Components are generally soldered on the PCB. Advanced PCBs may contain components embedded in the substrate, PCBs can be single sided, double sided or multi-layer. Conductors on different layers are connected with vias, multi-layer PCBs allow for much higher component density. FR-4 glass epoxy is the primary insulating substrate, a basic building block of the PCB is an FR-4 panel with a thin layer of copper foil laminated to one or both sides. In multi-layer boards multiple layers of material are laminated together, printed circuit boards are used in all but the simplest electronic products. Alternatives to PCBs include wire wrap and point-to-point construction, PCBs require the additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Manufacturing circuits with PCBs is cheaper and faster than other wiring methods as components are mounted and wired with one single part. A minimal PCB with a component used for easier prototyping is called a breakout board. When the board has no embedded components it is correctly called a printed wiring board or etched wiring board. However, the printed wiring board has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly, the IPC preferred term for assembled boards is circuit card assembly, and for assembled backplanes it is backplane assemblies. The term PCB is used both for bare and assembled boards. The world market for bare PCBs exceeded $60.2 billion in 2014, initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the diagram the component pin pads were laid out on the mylar. Rub-on dry transfers of common component footprints increased efficiency, traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout, to fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coating on the blank copper-clad boards. Modern PCBs are designed with dedicated software, generally in the following steps. Card dimensions and template are decided based on required circuitry and case of the PCB, the positions of the components and heat sinks are determined
20.
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
21.
Eutectic system
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It is only in this atomic/molecular ratio that the eutectic system melts as a whole, at a specific temperature the super-lattice releasing at once all its components into a liquid mixture. The eutectic temperature is the lowest possible melting temperature over all of the ratios for the involved component species. Conversely, as a non-eutectic mixture cools down, each component will solidify at a distinct temperature. The coordinates defining a eutectic point on a phase diagram are the percentage ratio. Not all binary alloys have eutectic points because the electrons of the component species are not always compatible, in any mixing ratio. The term eutectic was coined in 1884 by British physicist and chemist Frederick Guthrie, tangibly, this means the liquid and two solid solutions all coexist at the same time and are in chemical equilibrium. There is also a thermal arrest for the duration of the change of phase during which the temperature of the system does not change, the resulting solid macrostructure from a eutectic reaction depends on a few factors. The most important factor is how the two solid solutions nucleate and grow, the most common structure is a lamellar structure, but other possible structures include rodlike, globular, and acicular. Compositions of eutectic systems that are not at the composition can be classified as hypoeutectic or hypereutectic. As the temperature of a composition is lowered the liquid mixture will precipitate one component of the mixture before the other. In a hypereutectic solution, there will be a phase of species β whereas a hypoeutectic solution will have a proeutectic α phase. Eutectic alloys have two or more materials and have a eutectic composition, when a non-eutectic alloy solidifies, its components solidify at different temperatures, exhibiting a plastic melting range. Conversely, when a well-mixed, eutectic alloy melts, it does so at a single, some uses include, NEMA Eutectic Alloy Overload Relays for electrical protection of 3-phase motors for pumps, fans, conveyors, and other factory process equipment. The eutectic nature of salt and water is exploited when salt is spread on roads to aid snow removal, ethanol–water has an unusually biased eutectic point, i. e. it is close to pure ethanol, which sets the maximum proof obtainable by fractional freezing. Solar salt, 60% NaNO3 and 40% KNO3, forms a eutectic molten salt mixture which is used for energy storage in concentrated solar power plants. To reduce the melting point in the solar molten salts calcium nitrate is used in the following proportion, 42% Ca2, 43% KNO3. Lidocaine and prilocaine—both are solids at room temperature—form a eutectic that is an oil with a 16 °C melting point that is used in mixture of local anesthetic preparations. Menthol and camphor, both solids at room temperature, form a eutectic that is a liquid at room temperature in the proportions,8,2,7,3,6,4
22.
Aluminium
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Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
23.
Bismuth
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Bismuth is a chemical element with the symbol Bi and atomic number 83. Bismuth, a pentavalent post-transition metal and one of the pnictogens, chemically resembles its lighter homologs arsenic, elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead and it is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. Bismuth is the most naturally diamagnetic element, and has one of the lowest values of thermal conductivity among metals, Bismuth metal has been known since ancient times, although it was often confused with lead and tin, which share some physical properties. Bismuth was long considered the element with the highest atomic mass that is stable, because of its tremendously long half-life, bismuth may still be considered stable for almost all purposes. Bismuth compounds account for half the production of bismuth. They are used in cosmetics, pigments, and a few pharmaceuticals, notably bismuth subsalicylate, bismuths unusual propensity to expand upon freezing is responsible for some of its uses, such as in casting of printing type. Bismuth has unusually low toxicity for a heavy metal, as the toxicity of lead has become more apparent in recent years, there is an increasing use of bismuth alloys as a replacement for lead. The name bismuth dates from around the 1660s, and is of uncertain etymology and it is one of the first 10 metals to have been discovered. Bismuth appears in the 1660s, from obsolete German Bismuth, Wismut, Wissmuth, the New Latin bisemutum is from the German Wismuth, perhaps from weiße Masse, white mass. The element was confused in early times with tin and lead because of its resemblance to those elements, Bismuth has been known since ancient times, so no one person is credited with its discovery. Agricola, in De Natura Fossilium states that bismuth is a metal in a family of metals including tin. This was based on observation of the metals and their physical properties, miners in the age of alchemy also gave bismuth the name tectum argenti, or silver being made, in the sense of silver still in the process of being formed within the Earth. Bismuth was also known to the Incas and used in a bronze alloy for knives. Bismuth is a metal with a white, silver-pink hue, often occurring in its native form. The spiral, stair-stepped structure of crystals is the result of a higher growth rate around the outside edges than on the inside edges. The variations in the thickness of the layer that forms on the surface of the crystal causes different wavelengths of light to interfere upon reflection. When burned in oxygen, bismuth burns with a blue flame and its toxicity is much lower than that of its neighbors in the periodic table, such as lead, antimony, and polonium
24.
Silver
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Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, gold, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, jewelry, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table, copper and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft, ductile and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm. The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
25.
Flux (metallurgy)
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In metallurgy, a flux is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time and they are used in both extractive metallurgy and metal joining. Some of the earliest known fluxes were carbonate of soda, potash, charcoal, coke, borax, lime, lead sulfide, iron ore was also used as a flux in the smelting of copper. As cleaning agents, fluxes facilitate soldering, brazing, and welding by removing oxidation from the metals to be joined, the slag is a liquid mixture of ash, flux, and other impurities. This reduction of slag viscosity with temperature, increasing the flow of slag in smelting, is the origin of the word flux in metallurgy. Fluxes are also used in foundries for removing impurities from molten nonferrous metals such as aluminium, in high-temperature metal joining processes, the primary purpose of flux is to prevent oxidation of the base and filler materials. Tin-lead solder attaches very well to copper, but poorly to the oxides of copper. Flux is a substance which is inert at room temperature. Additionally, flux allows solder to flow easily on the piece rather than forming beads as it would otherwise. In some applications molten flux also serves as a heat transfer medium, fluxes for soft soldering are typically of organic nature, though inorganic fluxes, usually based on halogenides and/or acids, are also used in non-electronics applications. Fluxes for brazing operate at higher temperatures and are therefore mostly inorganic. Organic fluxes typically consist of four components, Activators - chemicals disrupting/dissolving the metal oxides. Their role is to expose unoxidized, easily wettable metal surface and aid soldering by other means, highly active fluxes contain chemicals that are corrosive at room temperature. The compounds used include metal halides, hydrochloric acid, phosphoric acid, Salts of mineral acids with amines are also used as aggressive activators. Aggressive fluxes typically facilitate corrosion, require careful removal, and are unsuitable for finer work, Activators for fluxes for soldering and brazing aluminium often contain fluorides. Milder activators begin to react with oxides only at elevated temperature, typical compounds used are carboxylic acids and sometimes amino acids. Some milder fluxes also contain halides or organohalides, vehicles - high-temperature tolerant chemicals in the form of non-volatile liquids or solids with suitable melting point, they are generally liquid at soldering temperatures. Solid vehicles tend to be based on natural or modified rosin or natural or synthetic resins, water-soluble organic fluxes tend to contain vehicles based on high-boiling polyols - glycols, diethylene glycol and higher polyglycols, polyglycol-based surfactants and glycerol
26.
Redox
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Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
27.
Charcoal
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Charcoal is a lightweight, black residue, consisting of carbon and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis- the heating of wood or other substances in the absence of oxygen, the whole pile is covered with turf or moistened clay. The firing is begun at the bottom of the flue, the success of the operation depends upon the rate of the combustion. The operation is so delicate that it was left to colliers. They often lived alone in small huts in order to tend their wood piles, for example, in the Harz Mountains of Germany, charcoal burners lived in conical huts called Köten which are still much in evidence today. The massive production of charcoal was a cause of deforestation. The increasing scarcity of easily harvested wood was a factor behind the switch to fossil fuel equivalents, mainly coal. Charcoal made at 300 °C is brown, soft and friable, and readily inflames at 380 °C, made at higher temperatures it is hard and brittle, in Finland and Scandinavia, the charcoal was considered the by-product of wood tar production. The best tar came from pine, thus pinewoods were cut down for tar pyrolysis, the residual charcoal was widely used as substitute for metallurgical coke in blast furnaces for smelting. Tar production led to deforestation, it has been estimated all Finnish forests are younger than 300 years. The end of tar production at the end of the 19th century resulted in rapid re-forestation, the charcoal briquette was first invented and patented by Ellsworth B. A. Zwoyer of Pennsylvania in 1897 and was produced by the Zwoyer Fuel Company. The process was popularized by Henry Ford, who used wood. Ford Charcoal went on to become the Kingsford Company, Charcoal has been made by various methods. The traditional method in Britain used a clamp and this is essentially a pile of wooden logs leaning against a chimney. The chimney consists of 4 wooden stakes held up by some rope, the logs are completely covered with soil and straw allowing no air to enter. It must be lit by introducing some burning fuel into the chimney, if the soil covering gets torn by the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air from entering, the true art of this production method is in managing the sufficient generation of heat, and its transfer to wood parts in the process of being carbonised. A strong disadvantage of this method is the huge amount of emissions that are harmful to human health
28.
Rosin
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It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperature and it chiefly consists of various resin acids, especially abietic acid. The term colophony comes from colophonia resina, Latin for resin from Colophon, Rosin is an ingredient in printing inks, photocopying and laser printing paper, varnishes, adhesives, soap, paper sizing, soda, soldering fluxes, and sealing wax. Rosin can be used as an agent in medicines and chewing gum. It is denoted by E number E915, a related glycerol ester can be used as an emulsifier in soft drinks. In pharmaceuticals, rosin forms an ingredient in several plasters and ointments, in industry, rosin is a flux used in soldering. It is frequently seen as the burnt or clear residue around new soldering, a mixture of pitch and rosin is used to make a surface against which glass is polished when making optical components such as lenses. Rosin is added in quantities to traditional linseed oil/sand gap fillers. When mixed with waxes and oils, rosin is the ingredient of mystic smoke, a gum which. Extra substances such as beeswax, gold, silver, tin, or meteoric iron are added to the rosin to modify its stiction/friction properties. Powdered rosin can be applied to new hair, for example with a pad or cloth. Rosin is often applied to the bow before playing the instrument, lighter rosin is generally preferred for violins and violas, and in high-humidity climates, while darker rosins are preferred for cellos, and for players in cool, dry areas. There are also specific, distinguishing types for basses—for more see Bow, violin rosin can be applied to the bridges in other musical instruments, such as the banjo and banjolele, in order to prevent the bridge from moving during vigorous playing. Ballet, flamenco, and Irish dancers are known to rub the tips and it was at one time used in the same way in fencing and is still used as such by boxers. Gymnasts and team handball players use it to improve grip, rock climbers have used it in some locations, but it fouls the rock, so usage is now highly discouraged. Olympic weightlifters rub the soles of their boots in rosin to improve traction on the platform. It is applied onto the line of drag racing courses used to improve traction. Bull riders rub rosin on their rope and glove for additional grip, baseball pitchers and ten-pin bowlers may use a small cloth bag of powdered rosin for better ball control
29.
Pine
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A pine is any conifer in the genus Pinus, /ˈpiːnuːs/, of the family Pinaceae. Pinus is the genus in the subfamily Pinoideae. The Plant List compiled by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts 126 species names of pines as current, together with 35 unresolved species, the modern English name pine derives from Latin pinus, which some have traced to the Indo-European base *pīt- ‘resin’. Before the 19th century, pines were often referred to as firs, the genus is divided into three subgenera, which can be distinguished by cone, seed, and leaf characters, Pinus subg. Pinus, the yellow, or hard pine group, generally harder wood. Ducampopinus, the foxtail or pinyon group Pinus subg, strobus, the white, or soft pine group, generally with softer wood and five needles per fascicle Most regions of the Northern Hemisphere host some native species of pines. One species crosses the equator in Sumatra to 2°S, in North America, various species occur in regions at latitudes from as far north as 66°N to as far south as 12°N. Various species have been introduced to temperate and subtropical regions of both hemispheres, where they are grown as timber or cultivated as ornamental plants in parks, a number of such introduced species have become invasive and threaten native ecosystems. Pine trees are evergreen, coniferous trees growing 3–80 m tall. The smallest are Siberian dwarf pine and Potosi pinyon, and the tallest is a 81.79 m tall ponderosa pine located in southern Oregons Rogue River-Siskiyou National Forest, the bark of most pines is thick and scaly, but some species have thin, flaky bark. The branches are produced in regular pseudo whorls, actually a very tight spiral, the spiral growth of branches, needles, and cone scales are arranged in Fibonacci number ratios. The new spring shoots are sometimes called candles, they are covered in brown or whitish bud scales and point upward at first, then turn green. These candles offer foresters a means to evaluate fertility of the soil, pines are long-lived, and typically reach ages of 100–1,000 years, some even more. The longest-lived is the Great Basin bristlecone pine, Pinus longaeva, one individual of this species, dubbed Methuselah, is one of the worlds oldest living organisms at around 4,600 years old. This tree can be found in the White Mountains of California, an older tree, now cut down, was dated at 4,900 years old. It was discovered in a grove beneath Wheeler Peak and it is now known as Prometheus after the Greek immortal, pines have four types of leaf, Seed leaves on seedlings, born in a whorl of 4–24. Juvenile leaves, which follow immediately on seedlings and young plants, 2–6 cm long, single, green or often blue-green and these are produced for six months to five years, rarely longer. Scale leaves, similar to bud scales, small, brown and non-photosynthetic, needles, the adult leaves, are green and bundled in clusters called fascicles
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Hydrochloric acid
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Hydrochloric acid is a corrosive, strong mineral acid with many industrial uses. A colorless, highly pungent solution of chloride in water. Free hydrochloric acid was first formally described in the 16th century by Libavius, later, it was used by chemists such as Glauber, Priestley, and Davy in their scientific research. It has numerous applications, including household cleaning, production of gelatin and other food additives, descaling. About 20 million tonnes of acid are produced worldwide annually. It is also found naturally in gastric acid, Hydrochloric acid was known to European alchemists as spirits of salt or acidum salis. Both names are used, especially in other languages, such as German, Salzsäure, Dutch, Zoutzuur, Swedish, Saltsyra, Turkish, Tuz Ruhu, Polish, kwas solny and Chinese. Gaseous HCl was called marine acid air, the old name muriatic acid has the same origin, and this name is still sometimes used. The name hydrochloric acid was coined by the French chemist Joseph Louis Gay-Lussac in 1814, aqua regia, a mixture consisting of hydrochloric and nitric acids, prepared by dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, a 13th-century European alchemist. Other references suggest that the first mention of aqua regia is in Byzantine manuscripts dating to the end of the 13th century, free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, during the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process developed by Nicolas Leblanc of Issoundun, France enabled cheap large-scale production of sodium carbonate, in this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the British Alkali Act 1863 and similar legislation in other countries, after the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale. In the 20th century, the Leblanc process was replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was already settled as an important chemical in numerous applications. After the year 2000, hydrochloric acid is made by absorbing by-product hydrogen chloride from industrial organic compounds production. Hydrochloric acid is the salt of hydronium ion, H3O+ and chloride and it is usually prepared by treating HCl with water. H C l + H2 O ⟶ H3 O + + C l − Hydrochloric acid can therefore be used to prepare salts called chlorides, Hydrochloric acid is a strong acid, since it is completely dissociated in water
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Surface tension
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Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible. Surface tension allows insects, usually denser than water, to float, at liquid-air interfaces, surface tension results from the greater attraction of liquid molecules to each other than to the molecules in the air. The net effect is a force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. Thus, the surface becomes under tension from the imbalanced forces, because of the relatively high attraction of water molecules for each other through a web of hydrogen bonds, water has a higher surface tension compared to that of most other liquids. Surface tension is an important factor in the phenomenon of capillarity, Surface tension has the dimension of force per unit length, or of energy per unit area. The two are equivalent, but when referring to energy per unit of area, it is common to use the surface energy. In materials science, surface tension is used for either surface stress or surface free energy, the cohesive forces among liquid molecules are responsible for the phenomenon of surface tension. In the bulk of the liquid, each molecule is pulled equally in every direction by neighboring liquid molecules, the molecules at the surface do not have the same molecules on all sides of them and therefore are pulled inwards. This creates some internal pressure and forces liquid surfaces to contract to the minimal area, Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a shape by the imbalance in cohesive forces of the surface layer. In the absence of forces, including gravity, drops of virtually all liquids would be approximately spherical. The spherical shape minimizes the necessary wall tension of the surface according to Laplaces law. Another way to view surface tension is in terms of energy, a molecule in contact with a neighbor is in a lower state of energy than if it were alone. The interior molecules have as many neighbors as they can possibly have, for the liquid to minimize its energy state, the number of higher energy boundary molecules must be minimized. The minimized quantity of boundary molecules results in a surface area. As a result of surface area minimization, a surface will assume the smoothest shape it can, since any curvature in the surface shape results in greater area, a higher energy will also result. Consequently, the surface will push back against any curvature in much the way as a ball pushed uphill will push back to minimize its gravitational potential energy. Bubbles in pure water are unstable, the addition of surfactants, however, can have a stabilizing effect on the bubbles
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Corrosive substance
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A corrosive substance is one that will destroy and damage other substances with which it comes into contact. It may attack a variety of materials, including metals and various organic compounds. The word corrosive is derived from the Latin verb corrodere, which means to gnaw, sometimes the word caustic is used as a synonym but caustic generally refers only to strong bases, particularly alkalis, and not to acids, oxidizers, or other non-alkaline corrosives. A low concentration of a substance is usually an irritant. Corrosion of non-living surfaces such as metals is a distinct process, for example, a water/air electrochemical cell corrodes iron to rust. In the Globally Harmonized System, both rapid corrosion of metals and chemical corrosion of skin qualify for the corrosive symbol. Corrosives are different from poisons in that corrosives are immediately dangerous to the tissues they contact, colloquially, corrosives may be called poisons but the concepts are technically distinct. However, there is nothing which precludes a corrosive from being a poison, common corrosives are either strong acids, strong bases, or concentrated solutions of certain weak acids or weak bases. They can exist as any state of matter, including liquids, solids, gases and their action on living tissue is mainly based on acid-base reactions of amide hydrolysis, ester hydrolysis and protein denaturation. Proteins are destroyed via amide hydrolysis while lipids are decomposed by ester hydrolysis and these reactions lead to chemical burns and are the mechanism of the destruction posed by corrosives. Some corrosives possess other properties which may extend their corrosive effects on living tissue. For example, sulfuric acid at a concentration is also a strong dehydrating agent, capable of dehydrating carbohydrates. This results in secondary thermal burns in addition to the chemical burns, some corrosives, such as nitric acid and concentrated sulfuric acid, are strong oxidizing agents as well, which significantly contributes to the extra damage caused. Hydrofluoric acid does not necessarily cause noticeable damage upon contact, but produces tissue damage, zinc chloride solutions are capable of destroying cellulose and corroding through paper and silk since the zinc cations in the solutions specifically attack hydroxyl groups, acting as a Lewis acid. In addition, some chemicals, mostly acids such as hydrochloric acid and nitric acid, are volatile. Inhalation can damage the respiratory tract, corrosive substances are most hazardous to eyesight. A drop of a corrosive may cause blindness within 2–10 seconds through opacification or direct destruction of the cornea, ingestion of corrosives can induce severe consequences, including serious damage of the gastrointestinal tract, which can lead to vomiting, severe stomach aches, and death. Common corrosive chemicals are classified into, Acids Strong acids – the most common are acid, nitric acid
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Classification chart
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Classification chart or classification tree is a synopsis of the classification scheme, designed to illustrate the structure of any particular field. Classification is the process in which ideas and objects are recognized, differentiated, and understood, according to Brinton in a classification chart the facts, data etc. are arranged so that the place of each in relation to all others is readily seen. Quantities need not be given, although a quantitative analysis adds to the value of a classification chart, karsten explained, that in all chart-making, the material to be shown must be accurately compiled before it can be charted. For an understanding of the chart, we must delve somewhat into the mysteries of the classification. The art of classification calls into play the power of visualizing a whole together with its parts, Early examples of classification chart are, The illustrations of the Carl Linnaeus 1735 classification of animals and his classification of plants in his Classes Plantarum 1738. In 1752 Jean le Rond dAlembert and Denis Diderot produced a system of human knowledge produced for the Encyclopédie. Augustin Augiers Arbre Botanique In 1840 Edward Hitchcock inserted a paleontological chart in his Elementary Geology and it shows a branching diagram of the plant and animal kingdom against a geological background. The tree of life image that appeared in Darwins On the Origin of Species,1859 Early classification chart are often visualized in a tree structure, modern charts can also be presented in table of as infographic. The term classification chart came into use in the 20th century, willard Cope Brinton was one of the first to devoted a whole chapter on classification charts. Chart Decision tree Decision tree learning Phylogenetic trees Tree of life Tree structure
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Brass
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Brass is a metal alloy made of copper and zinc, the proportions of zinc and copper can be varied to create a range of brasses with varying properties. It is an alloy, atoms of the two constituents may replace each other within the same crystal structure. By comparison, bronze is principally an alloy of copper and tin, however, bronze and brass may also include small proportions of a range of other elements including arsenic, phosphorus, aluminium, manganese, and silicon. The term is applied to a variety of brasses. Modern practice in museums and archaeology increasingly avoids both terms for objects in favour of the all-embracing copper alloy. It is also used in zippers, Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brass has higher malleability than bronze or zinc, the relatively low melting point of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard, the density of brass is 8.4 to 8.73 grams per cubic centimetre. Today, almost 90% of all alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet, Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the form and size. The general softness of brass means that it can often be machined without the use of cutting fluid, aluminium makes brass stronger and more corrosion-resistant. Aluminium also causes a highly beneficial hard layer of oxide to be formed on the surface that is thin, transparent. Tin has an effect and finds its use especially in seawater applications. Combinations of iron, aluminium, silicon and manganese make brass wear and tear resistant, to enhance the machinability of brass, lead is often added in concentrations of around 2%. Since lead has a melting point than the other constituents of the brass. The pattern the globules form on the surface of the brass increases the available surface area which in turn affects the degree of leaching. In addition, cutting operations can smear the lead globules over the surface and these effects can lead to significant lead leaching from brasses of comparatively low lead content
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Wetting
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Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. The degree of wetting is determined by a balance between adhesive and cohesive forces. Wetting deals with the three phases of materials, gas, liquid, and solid and it is now a center of attention in nanotechnology and nanoscience studies due to the advent of many nanomaterials in the past two decades. Wetting is important in the bonding or adherence of two materials, Wetting and the surface forces that control wetting are also responsible for other related effects, including capillary effects. There are two types of wetting, non-reactive wetting and active wetting, adhesive forces between a liquid and solid cause a liquid drop to spread across the surface. Cohesive forces within the cause the drop to ball up. The contact angle, as seen in Figure 1, is the angle at which the liquid–vapor interface meets the solid–liquid interface, the contact angle is determined by the result between adhesive and cohesive forces. As the tendency of a drop to spread out over a flat, solid surface increases, thus, the contact angle provides an inverse measure of wettability. A contact angle less than 90° usually indicates that wetting of the surface is very favorable, contact angles greater than 90° generally means that wetting of the surface is unfavorable, so the fluid will minimize contact with the surface and form a compact liquid droplet. For water, a surface may also be termed hydrophilic. Superhydrophobic surfaces have contact angles greater than 150°, showing almost no contact between the drop and the surface. This is sometimes referred to as the Lotus effect, the table describes varying contact angles and their corresponding solid/liquid and liquid/liquid interactions. For nonwater liquids, the term lyophilic is used for low contact angle conditions, similarly, the terms omniphobic and omniphilic apply to both polar and apolar liquids. Liquids can interact with two types of solid surfaces. Traditionally, solid surfaces have been divided into high-energy solids and low-energy types, the relative energy of a solid has to do with the bulk nature of the solid itself. Solids such as metals, glasses, and ceramics are known as hard solids because the bonds that hold them together are very strong. Thus, it takes an input of energy to break these solids. Most molecular liquids achieve complete wetting with high-energy surfaces, the other type of solids is weak molecular crystals where the molecules are held together essentially by physical forces
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Capillary action
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Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. It occurs because of forces between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of surface tension, the first recorded observation of capillary action was by Leonardo da Vinci. A former student of Galileo, Niccolò Aggiunti, was said to have investigated capillary action, boyle then reported an experiment in which he dipped a capillary tube into red wine and then subjected the tube to a partial vacuum. Some thought that liquids rose in capillaries because air couldnt enter capillaries as easily as liquids, others thought that the particles of liquid were attracted to each other and to the walls of the capillary. They derived the Young–Laplace equation of capillary action, by 1830, the German mathematician Carl Friedrich Gauss had determined the boundary conditions governing capillary action. In 1871, the British physicist William Thomson determined the effect of the meniscus on a liquids vapor pressure—a relation known as the Kelvin equation, German physicist Franz Ernst Neumann subsequently determined the interaction between two immiscible liquids. Albert Einsteins first paper, which was submitted to Annalen der Physik in 1900, was on capillarity, a common apparatus used to demonstrate the first phenomenon is the capillary tube. When the lower end of a glass tube is placed in a liquid, such as water. Adhesion occurs between the fluid and the inner wall pulling the liquid column up until there is a sufficient mass of liquid for gravitational forces to overcome these intermolecular forces. So, a tube will draw a liquid column higher than a wider tube will. Capillary action is essential for the drainage of constantly produced tear fluid from the eye, wicking is the absorption of a liquid by a material in the manner of a candle wick. Paper towels absorb liquid through capillary action, allowing a fluid to be transferred from a surface to the towel, the small pores of a sponge act as small capillaries, causing it to absorb a large amount of fluid. Some textile fabrics are said to use capillary action to wick sweat away from the skin and these are often referred to as wicking fabrics, after the capillary properties of candle and lamp wicks. Capillary action is observed in thin layer chromatography, in which a solvent moves vertically up a plate via capillary action, in this case the pores are gaps between very small particles. Capillary action draws ink to the tips of fountain pen nibs from a reservoir or cartridge inside the pen, in hydrology, capillary action describes the attraction of water molecules to soil particles. Capillary action is responsible for moving groundwater from wet areas of the soil to dry areas, differences in soil potential drive capillary action in soil. Thus the thinner the space in which the water can travel, for a water-filled glass tube in air at standard laboratory conditions, γ =0.0728 N/m at 20 °C, ρ =1000 kg/m3, and g =9.81 m/s2
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Ultimate tensile strength
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In other words, tensile strength resists tension, whereas compressive strength resists compression. Ultimate tensile strength is measured by the stress that a material can withstand while being stretched or pulled before breaking. In the study of strength of materials, tensile strength, compressive strength, some materials break very sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, experience some plastic deformation, the UTS is usually found by performing a tensile test and recording the engineering stress versus strain. The highest point of the curve is the UTS. It is a property, therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, Tensile strengths are rarely used in the design of ductile members, but they are important in brittle members. They are tabulated for common materials such as alloys, composite materials, ceramics, plastics, Tensile strength can be defined for liquids as well as solids under certain conditions. Tensile strength is defined as a stress, which is measured as force per unit area, for some non-homogeneous materials it can be reported just as a force or as a force per unit width. In the International System of Units, the unit is the pascal, or, equivalently to pascals, Many materials can display linear elastic behavior, defined by a linear stress–strain relationship, as shown in the left figure up to point 3. Beyond this elastic region, for materials, such as steel. A plastically deformed specimen does not completely return to its original size, for many applications, plastic deformation is unacceptable, and is used as the design limitation. The reversal point is the stress on the engineering stress–strain curve. The UTS is not used in the design of static members because design practices dictate the use of the yield stress. It is, however, used for quality control, because of the ease of testing and it is also used to roughly determine material types for unknown samples. The UTS is a common engineering parameter to design members made of material because such materials have no yield point. Typically, the testing involves taking a sample with a fixed cross-sectional area. When testing some metals, indentation hardness correlates linearly with tensile strength and this important relation permits economically important nondestructive testing of bulk metal deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness testers
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Soldering iron
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A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it can flow into the joint between two workpieces, a soldering iron is composed of a heated metal tip and an insulated handle. Heating is often achieved electrically, by passing a current through a resistive heating element. Cordless irons can be heated by combustion of gas stored in a small tank, simple irons less commonly used than in the past were simply a large copper bit on a handle, heated in a flame. Soldering irons are most often used for installation, repairs, high-volume production lines use other soldering methods. Large irons may be used for soldering joints in sheet metal objects, less common uses include pyrography and plastic welding. For electrical and electronics work, an iron, a power rating between 15 and 35 watts, is used. Some irons are temperature-controlled, running at a temperature in the same way as a soldering station. Simple irons run at a temperature determined by thermal equilibrium. Small irons heated by a battery, or by combustion of a gas such as butane in a small self-contained tank, the operating temperature of these irons is not regulated directly, gas irons may change power by adjusting gas flow. Simple soldering irons reach a temperature determined by thermal equilibrium, dependent upon power input and cooling by the environment and the materials it comes into contact with. The iron temperature will drop when in contact with a mass of metal such as a chassis. A variety of means are used to control temperature, the simplest of these is a variable power control, much like a light dimmer, which changes the equilibrium temperature of the iron without automatically measuring or regulating the temperature. Another type of system uses a thermostat, often inside the irons tip, another approach is to use magnetized soldering tips which lose their magnetic properties at a specific temperature, the Curie point. As long as the tip is magnetic, it closes a switch to power to the heating element. When it exceeds the design temperature it opens the contacts, cooling until the temperature enough to restore magnetisation. More complex Curie-point irons circulate a high-frequency AC current through the tip, the station will normally have a stand for the hot iron when not in use, and a wet sponge for cleaning. It is most commonly used for soldering electronic components, the main purpose of the soldering tweezers is to melt solder in the correct place, components are usually moved by simple tweezers or vacuum pickup
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Soldering gun
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A soldering gun is an approximately pistol-shaped, electrically powered tool for soldering metals using tin-based solder to achieve a strong mechanical bond with good electrical contact. The tool has a switch so it can be easily operated with one hand. A soldering tip, made of a loop of copper wire, is secured to the end of the transformer secondary by screws. When the primary of the transformer is energized, several hundred amperes of current flow through the secondary and very rapidly heat the copper tip. Since the tip has a higher resistance than the rest of the tubular copper winding. A tap on the winding is often used to light a pilot lamp which also lights the workpiece. The soldering gun is useful when soldered joints must be made intermittently, a constant-heat device has to be set in a safe place when powered but not actually in use, to prevent damage or injury. The fast-switching gun cools quickly enough to be set down a few seconds after use, soldering guns are used where more heat is needed than from the lower-power soldering irons. They can be used for electrical connections, stained glass assembly. Typical soldering guns are rated at 100 to 240 watts power, a gun may include a two-stage trigger to give two heat settings. Tips designed for cutting and shaping plastic are available, soldering guns for general home use may be supplied with a kit of different tips, the temperature of the soldering tip is regulated manually by holding the button until the solder melts, and then releasing it. When the solder is about to start solidifying, the button is pressed again, an experienced worker develops the skill to regulate the temperature according to need. The copper tip slowly dissolves in the solder and eventually has to be replaced, the soldering gun generates an electromagnetic spike when the button is released, which can be a problem for electromagnetically-sensitive devices. The spike can be seen when a high-efficiency LED is soldered, the heavy magnetic field produced by the tip can attract and hold small ferrous metal pieces. Pistol-grip electrically-heated soldering tools had been used since the 1920s, in 1941 Carl E. Weller invented and later obtained U. S. Patent 2,405,866 for a soldering tool which heated and cooled rapidly, essentially as described in this article. Weller formed a company to manufacture and sell his invention commercially in 1946, the Weller company was bought in 1970 and merged into the Cooper Industries group, retaining the Weller brand for soldering equipment
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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
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Alternating current
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Alternating current, is an electric current which periodically reverses direction, whereas direct current flows only in one direction. A common source of DC power is a cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, the usual waveform of alternating current in most electric power circuits is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves, audio and radio signals carried on electrical wires are also examples of alternating current. These types of alternating current carry information encoded onto the AC signal and these currents typically alternate at higher frequencies than those used in power transmission. Electrical energy is distributed as alternating current because AC voltage may be increased or decreased with a transformer, use of a higher voltage leads to significantly more efficient transmission of power. The power losses in a conductor are a product of the square of the current and this means that when transmitting a fixed power on a given wire, if the current is halved, the power loss will be four times less. Power is often transmitted at hundreds of kilovolts, and transformed to 100–240 volts for domestic use, high voltages have disadvantages, such as the increased insulation required, and generally increased difficulty in their safe handling. In a power plant, energy is generated at a convenient voltage for the design of a generator, near the loads, the transmission voltage is stepped down to the voltages used by equipment. Consumer voltages vary somewhat depending on the country and size of load, the voltage delivered to equipment such as lighting and motor loads is standardized, with an allowable range of voltage over which equipment is expected to operate. Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world, high-voltage direct-current electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power. HVDC systems, however, tend to be expensive and less efficient over shorter distances than transformers. Three-phase electrical generation is very common, the simplest way is to use three separate coils in the generator stator, physically offset by an angle of 120° to each other. Three current waveforms are produced that are equal in magnitude and 120° out of phase to each other, if coils are added opposite to these, they generate the same phases with reverse polarity and so can be simply wired together. In practice, higher pole orders are commonly used, for example, a 12-pole machine would have 36 coils. The advantage is that lower rotational speeds can be used to generate the same frequency, for example, a 2-pole machine running at 3600 rpm and a 12-pole machine running at 600 rpm produce the same frequency, the lower speed is preferable for larger machines. If the load on a system is balanced equally among the phases. Even in the worst-case unbalanced load, the current will not exceed the highest of the phase currents
