A building, or edifice, is a structure with a roof and walls standing more or less permanently in one place, such as a house or factory. Buildings come in a variety of sizes and functions, have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, aesthetic reasons. To better understand the term building compare the list of nonbuilding structures. Buildings serve several societal needs – as shelter from weather, living space, privacy, to store belongings, to comfortably live and work. A building as a shelter represents a physical division of the outside. Since the first cave paintings, buildings have become objects or canvasses of much artistic expression. In recent years, interest in sustainable planning and building practices has become an intentional part of the design process of many new buildings; the word building is the act of making it. As a noun, a building is'a structure that has a roof and walls and stands more or less permanently in one place'.
In the broadest interpretation a fence or wall is a building. However, the word structure is used more broadly than building including natural and man-made formations and does not have walls. Structure is more to be used for a fence. Sturgis' Dictionary included that " differs from architecture in excluding all idea of artistic treatment; as a verb, building is the act of construction. Structural height in technical usage is the height to the highest architectural detail on building from street-level. Depending on how they are classified and masts may or may not be included in this height. Spires and masts used as antennas are not included; the definition of a low-rise vs. a high-rise building is a matter of debate, but three storeys or less is considered low-rise. A report by Shinichi Fujimura of a shelter built 500 000 years ago is doubtful since Fujimura was found to have faked many of his findings. Supposed remains of huts found at the Terra Amata site in Nice purportedly dating from 200 000 to 400 000 years ago have been called into question.
There is clear evidence of homebuilding from around 18 000 BC. Buildings became common during the Neolithic. Single-family residential buildings are most called houses or homes. Multi-family residential buildings containing more than one dwelling unit are called a duplex or an apartment building. A condominium is an apartment rather than rents. Houses may be built in pairs, in terraces where all but two of the houses have others either side. Houses which were built as a single dwelling may be divided into apartments or bedsitters. Building types may range from huts to multimillion-dollar high-rise apartment blocks able to house thousands of people. Increasing settlement density in buildings is a response to high ground prices resulting from many people wanting to live close to work or similar attractors. Other common building materials are concrete or combinations of either of these with stone. Residential buildings have different names for their use depending if they are seasonal include holiday cottage or timeshare.
If the residents are in need of special care such as a nursing home, orphanage or prison. Many people lived in communal buildings called longhouses, smaller dwellings called pit-houses and houses combined with barns sometimes called housebarns. Buildings are defined to be substantial, permanent structures so other dwelling forms such as houseboats and motorhomes are dwellings but not buildings. Sometimes a group of inter-related builds are referred to as a complex – for example a housing complex, educational complex, hospital complex, etc; the practice of designing and operating buildings is most a collective effort of different groups of professionals and trades. Depending on the size and purpose of a particular building project, the project team may include: A real estate developer who secures funding for the project. Other possible design Engineer specialists may be involved such as Fire, facade engineers, building physics, Telecomms, AV (Audio V
A sanitary sewer or foul sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings to treatment facilities or disposal. Sanitary sewers are part of an overall system called sewerage. Sewage may be treated to control water pollution before discharge to surface waters. Sanitary sewers serving industrial areas carry industrial wastewater. Separate sanitary sewer systems are designed to transport sewage alone. In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. Sanitary sewers are distinguished from combined sewers, which combine sewage with stormwater runoff in one pipe. Sanitary sewer systems are beneficial. Sewage treatment is less effective when sanitary waste is diluted with stormwater, combined sewer overflows occur when runoff from heavy rainfall or snowmelt exceeds the hydraulic capacity of sewage treatment plants. To overcome these disadvantages, some cities built separate sanitary sewers to collect only municipal wastewater and exclude stormwater runoff collected in separate storm drains.
The decision between a combined sewer system or two separate systems is based on need for sewage treatment and cost of providing treatment during heavy rain events. Many cities with combined sewer systems built prior to installing sewage treatment have not replaced those sewer systems. In the developed world, sewers are pipes from buildings to one or more levels of larger underground trunk mains, which transport the sewage to sewage treatment facilities. Vertical pipes made of precast concrete, called manholes, connect the mains to the surface. Depending upon site application and use, these vertical pipes can be cylindrical, eccentric, or concentric; the manholes are used for access to the sewer pipes for inspection and maintenance, as a means to vent sewer gases. They facilitate vertical and horizontal angles in otherwise straight pipelines. Pipes conveying sewage from an individual building to a common gravity sewer line are called laterals. Branch sewers run under streets receiving laterals from buildings along that street and discharge by gravity into trunk sewers at manholes.
Larger cities may have sewers called interceptors. Design and sizing of sanitary sewers considers the population to be served over the anticipated life of the sewer, per capita wastewater production, flow peaking from timing of daily routines. Minimum sewer diameters are specified to prevent blockage by solid materials flushed down toilets. Commercial and industrial wastewater flows are considered, but diversion of surface runoff to storm drains eliminates wet weather flow peaks of inefficient combined sewers. Pumps may be necessary where gravity sewers serve areas at lower elevations than the sewage treatment plant, or distant areas at similar elevations. A lift station is a sewer sump; the pump may discharge to another gravity sewer at that location or may discharge through a pressurized force main to some distant location. Effluent sewer systems called septic tank effluent drainage or solids-free sewer systems, have septic tanks that collect sewage from residences and businesses, the effluent that comes out of the tank is sent to either a centralized sewage treatment plant or a distributed treatment system for further treatment.
Most of the solids are removed by the septic tanks, so the treatment plant can be much smaller than a typical plant. In addition, because of the vast reduction in solid waste, a pumping system can be used to move the wastewater rather than a gravity system; the pipes have small diameters 1.5 to 4 inches. Because the waste stream is pressurized, they can be laid just below the ground surface along the land's contour. Simplified sanitary sewers consist of small-diameter pipes around 100 millimetres laid at flat gradients. Although the investment cost for simplified sanitary sewers can be about half the cost of conventional sewers, the requirements for operation and maintenance are higher. Simplified sewers are most common in Brazil and are used in a number of other developing countries. In low-lying communities, wastewater is conveyed by vacuum sewer. Pipelines range in size from pipes of 6 inches in diameter to concrete-lined tunnels of up to 30 feet in diameter. A low pressure system uses a small grinder pump located at each point of connection a house or business.
Vacuum sewer systems use differential atmospheric pressure to move the liquid to a central vacuum station. Sanitary sewer overflow can occur due to blocked or broken sewer lines, infiltration of excessive stormwater or malfunction of pumps. In these cases untreated sewage is discharged from a sanitary sewer into the environment prior to reaching sewage treatment facilities. To avoid this, maintenance is required; the maintenance requirements vary with the type of sanitary sewer. In general, all sewers deteriorate with age, but infiltration and inflow are problems unique to sanitary sewers, since both combined sewers and storm drains are sized to carry these contributions. Holding infiltration to acceptable levels requires a higher standard of maintenance than necessary for structural integrity considerations of combined sewers. A comprehensive construction inspection program is required to prevent inappropriate connection of cellar and roof drains to sanitary sewers; the probability of inappropriate connecti
Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, petroleum, or peat. Production and trade in pine-derived tar was a major contributor in the economies of Northern Europe and Colonial America, its main use was in preserving wooden sailing vessels against rot. The largest user was the Royal Navy of the United Kingdom. Demand for tar declined with the advent of steel ships. Tar-like products can be produced from other forms of organic matter, such as peat. Mineral products resembling tar can be produced from fossil hydrocarbons, such as petroleum. Coal tar is produced from coal as a byproduct of coke production. "Tar" and "pitch" can be used interchangeably. There is a tendency to use "tar" for "pitch" for more solid substances. Both "tar" and "pitch" are applied to viscous forms of asphalt, such as the asphalt found in occurring tar pits. "Rangoon tar" known as "Burmese oil" or "Burmese naphtha", is a form of petroleum.
Oil sands exclusively produced in Alberta, are colloquially referred to as "tar sands" but are in fact composed of bitumen. Note, similar heavy crude grades from Venezuela are not referred to as "tar sands" by Wikipedia or the environmental community. In Northern Europe, the word "tar" refers to a substance, derived from the wood and roots of pine. In earlier times it was used as a water repellent coating for boats and roofs, it is still used as an additive in the flavoring of candy and other foods. Wood tar is microbicidal. Producing tar from wood was known in ancient Greece and has been used in Scandinavia since the Iron Age. For centuries, dating back at least to the 14th century, tar was among Sweden's most important exports. Sweden exported 13,000 barrels of tar in 1615 and 227,000 barrels in the peak year of 1863. Production nearly stopped in the early 20th century, when other chemicals replaced tar, wooden ships were replaced by steel ships. Traditional wooden boats are still sometimes tarred.
The heating of pine wood causes pitch to drip away from the wood and leave behind charcoal. Birch bark is used to make fine tar, known as "Russian oil", suitable for leather protection; the by-products of wood tar are charcoal. When deciduous tree woods are subjected to destructive distillation, the products are methanol and charcoal. Tar kilns are dry distillation ovens used in Scandinavia for producing tar from wood, they were built close from limestone or from more primitive holes in the ground. The bottom is sloped into an outlet hole to allow the tar to pour out; the wood is split into dimensions of a finger, stacked densely, covered tight with dirt and moss. If oxygen can enter, the wood might catch fire, the production would be ruined. On top of this, a fire lit. After a few hours, the tar continues to do so for a few days. Tar was used as tar paper and to seal the hulls of ships and boats. For millennia, wood tar was used to waterproof sails and boats, but today, sails made from inherently waterproof synthetic substances have reduced the demand for tar.
Wood tar is still used to seal traditional wooden boats and the roofs of historical shingle-roofed churches, as well as painting exterior walls of log buildings. Tar is a general disinfectant. Pine tar oil, or wood tar oil, is used for the surface treatment of wooden shingle roofs, boats and tubs and in the medicine and rubber industries. Pine tar has good penetration on the rough wood. An old wood tar oil recipe for the treatment of wood is one-third each genuine wood tar, balsam turpentine, boiled or raw linseed oil or Chinese tung oil. In Finland, wood tar was once considered a panacea reputed to heal "even those cut in twain through their midriff". A Finnish proverb states that "if sauna and tar won't help, the disease is fatal." Wood tar is used in traditional Finnish medicine because of its microbicidal properties. Wood tar is available diluted as tar water, which has numerous uses: As a flavoring for candies and alcohol; as a spice for food, like meat. As a scent for saunas. Tar water is mixed into water, turned into steam in the sauna.
As an anti-dandruff agent in shampoo. As a component of cosmetics. Mixing tar with linseed oil varnish produces tar paint. Tar paint has a translucent brownish hue and can be used to saturate and tone wood and protect it from weather. Tar paint can be toned with various pigments, producing translucent colors and preserving the wood texture. In English and French, "tar" is a substance derived from coal, it was one of the products of gasworks. Tar made from coal or petroleum is considered toxic and carcinogenic because of its high benzene content, though coal tar in low concentrations is used as a topical medicine. Coal and petroleum tar has a pungent odour. Coal tar is listed at number 1999 in the United Nations list of dangerous goods. Bitumen Creosote Pitch Pitch drop experiment Resin Rollins Tars Tarring and feathering Tar Heels Tar pit Tarmac Tar tar ^ "Geotimes – February 2005 – Mummy tar in ancient Egypt". Retrieved January 9, 2006. Details history and uses of "Rangoon Tar"
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus Gossypium in the mallow family Malvaceae. The fiber is pure cellulose. Under natural conditions, the cotton bolls will increase the dispersal of the seeds; the plant is a shrub native to tropical and subtropical regions around the world, including the Americas, Africa and India. The greatest diversity of wild cotton species is found followed by Australia and Africa. Cotton was independently domesticated in the New Worlds; the fiber is most spun into yarn or thread and used to make a soft, breathable textile. The use of cotton for fabric is known to date to prehistoric times. Although cultivated since antiquity, it was the invention of the cotton gin that lowered the cost of production that led to its widespread use, it is the most used natural fiber cloth in clothing today. Current estimates for world production are about 25 million tonnes or 110 million bales annually, accounting for 2.5% of the world's arable land.
China is the world's largest producer of cotton. The United States has been the largest exporter for many years. In the United States, cotton is measured in bales, which measure 0.48 cubic meters and weigh 226.8 kilograms. There are four commercially grown species of cotton, all domesticated in antiquity: Gossypium hirsutum – upland cotton, native to Central America, the Caribbean and southern Florida Gossypium barbadense – known as extra-long staple cotton, native to tropical South America Gossypium arboreum – tree cotton, native to India and Pakistan Gossypium herbaceum – Levant cotton, native to southern Africa and the Arabian Peninsula The two New World cotton species account for the vast majority of modern cotton production, but the two Old World species were used before the 1900s. While cotton fibers occur in colors of white, brown and green, fears of contaminating the genetics of white cotton have led many cotton-growing locations to ban the growing of colored cotton varieties; the word "cotton" has Arabic origins, derived from the Arabic word قطن.
This was the usual word for cotton in medieval Arabic. The word entered the Romance languages in the mid-12th century, English a century later. Cotton fabric was known to the ancient Romans as an import but cotton was rare in the Romance-speaking lands until imports from the Arabic-speaking lands in the medieval era at transformatively lower prices; the earliest evidence of cotton use in the Indian subcontinent has been found at the site of Mehrgarh and Rakhigarhi where cotton threads have been found preserved in copper beads. Cotton cultivation in the region is dated to the Indus Valley Civilization, which covered parts of modern eastern Pakistan and northwestern India between 3300 and 1300 BC; the Indus cotton industry was well-developed and some methods used in cotton spinning and fabrication continued to be used until the industrialization of India. Between 2000 and 1000 BC cotton became widespread across much of India. For example, it has been found at the site of Hallus in Karnataka dating from around 1000 BC.
Cotton bolls discovered in a cave near Tehuacán, have been dated to as early as 5500 BC, but this date has been challenged. More securely dated is the domestication of Gossypium hirsutum in Mexico between around 3400 and 2300 BC. In Peru, cultivation of the indigenous cotton species Gossypium barbadense has been dated, from a find in Ancon, to c. 4200 BC, was the backbone of the development of coastal cultures such as the Norte Chico and Nazca. Cotton was grown upriver, made into nets, traded with fishing villages along the coast for large supplies of fish; the Spanish who came to Mexico and Peru in the early 16th century found the people growing cotton and wearing clothing made of it. The Greeks and the Arabs were not familiar with cotton until the Wars of Alexander the Great, as his contemporary Megasthenes told Seleucus I Nicator of "there being trees on which wool grows" in "Indica"; this may be a reference to "tree cotton", Gossypium arboreum, a native of the Indian subcontinent. According to the Columbia Encyclopedia: Cotton has been spun and dyed since prehistoric times.
It clothed the people of ancient India and China. Hundreds of years before the Christian era, cotton textiles were woven in India with matchless skill, their use spread to the Mediterranean countries. In Iran, the history of cotton dates back to the Achaemenid era; the planting of cotton was common in Merv and Pars of Iran. In Persian poets' poems Ferdowsi's Shahname, there are references to cotton. Marco Polo refers to the major products including cotton. John Chardin, a French traveler of the 17th century who visited Safavid Persia, spoke approvingly of the vast cotton farms of Persia. During the Han dynasty, cotton was grown by Chinese peoples in the southern Chinese province of Yunnan. Egyptians spun cotton in the first seven centuries of the Christian era. Handheld roller cotton gins had been used in India since the 6th century, was introduced to other countries from there. Between the 12th and 14th centuries, dual-roller gins appeared in China; the Indian version of the dual-roller gin was preval
A boiler is a closed vessel in which fluid is heated. The fluid does not boil; the heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation and sanitation. In a fossil fuel power plant using a steam cycle for power generation, the primary heat source will be combustion of coal, oil, or natural gas. In some cases byproduct fuel such as the carbon-monoxide rich offgasses of a coke battery can be burned to heat a boiler. In a nuclear power plant, boilers called steam generators are heated by the heat produced by nuclear fission. Where a large volume of hot gas is available from some process, a heat recovery steam generator or recovery boiler can use the heat to produce steam, with little or no extra fuel consumed. In all cases the combustion product waste gases are separate from the working fluid of the steam cycle, making these systems examples of External combustion engines; the pressure vessel of a boiler is made of steel, or of wrought iron.
Stainless steel of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. However, ferritic stainless steel is used in superheater sections that will not be exposed to boiling water, electrically-heated stainless steel shell boilers are allowed under the European "Pressure Equipment Directive" for production of steam for sterilizers and disinfectors. In live steam models, copper or brass is used because it is more fabricated in smaller size boilers. Copper was used for fireboxes, because of its better formability and higher thermal conductivity. For much of the Victorian "age of steam", the only material used for boilermaking was the highest grade of wrought iron, with assembly by riveting; this iron was obtained from specialist ironworks, such as those in the Cleator Moor area, noted for the high quality of their rolled plate, suitable for use in critical applications such as high-pressure boilers. In the 20th century, design practice moved towards the use of steel, with welded construction, stronger and cheaper, can be fabricated more and with less labour.
Wrought iron boilers corrode far more than their modern-day steel counterparts, are less susceptible to localized pitting and stress-corrosion. That makes the longevity of older wrought-iron boilers far superior to that of welded steel boilers. Cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are termed "boilers" in some countries, their purpose is to produce hot water, not steam, so they run at low pressure and try to avoid boiling; the brittleness of cast iron makes it impractical for high-pressure steam boilers. The source of heat for a boiler is combustion of any of several fuels, such as wood, oil, or natural gas. Electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is used as a heat source for generating steam, either directly or, in most cases, in specialised heat exchangers called "steam generators". Heat recovery steam generators use. There are two methods to measure the boiler efficiency: Direct method Indirect methodDirect method: Direct method of boiler efficiency test is more usable or more common.
Boiler efficiency = power out / power in = / * 100%Q = rate of steam flow in kg/h Hg = enthalpy of saturated steam in kcal/kg Hf = enthalpy of feed water in kcal/kg q = rate of fuel use in kg/h GCV = gross calorific value in kcal/kg Indirect method: To measure the boiler efficiency in indirect method, we need a following parameter like: Ultimate analysis of fuel Percentage of O2 or CO2 at flue gas Flue gas temperature at outlet Ambient temperature in deg c and humidity of air in kg/kg GCV of fuel in kcal/kg Ash percentage in combustible fuel GCV of ash in kcal/kg Boilers can be classified into the following configurations: Pot boiler or Haycock boiler/Haystack boiler: A primitive "kettle" where a fire heats a filled water container from below. 18th century Haycock boilers produced and stored large volumes of low-pressure steam hardly above that of the atmosphere. These could burn wood or most coal. Efficiency was low. Flued boiler with one or two large flues—an early type or forerunner of fire-tube boiler.
Fire-tube boiler: Here, water fills a boiler barrel with a small volume left above to accommodate the steam. This is the type of boiler used in nearly all steam locomotives; the heat source is inside a furnace or firebox that has to be kept permanently surrounded by the water in order to maintain the temperature of the heating surface below the boiling point. The furnace can be situated at one end of a fire-tube which lengthens the path of the hot gases, thus augmenting the heating surface which can be further increased by making the gases reverse direction through a second parallel tube or a bundle of multiple tubes. In case of a locomotive-type boiler, a boiler
Polyurethane is a polymer composed of organic units joined by carbamate links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are available. Polyurethane polymers are traditionally and most formed by reacting a di- or tri poly-isocyanate with a polyol. Since polyurethanes contain two types of monomers, which polymerise one after the other, they are classed as alternating copolymers. Both the isocyanates and polyols used to make polyurethanes contain, on average, two or more functional groups per molecule. Polyurethanes are used in the manufacture of high-resilience foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, high performance adhesives, surface coatings and surface sealants, synthetic fibers, carpet underlay, hard-plastic parts and hoses. Otto Bayer and his coworkers at IG Farben in Leverkusen, first made polyurethanes in 1937.
The new polymers had some advantages over existing plastics that were made by polymerizing olefins or by polycondensation, were not covered by patents obtained by Wallace Carothers on polyesters. Early work focused on the production of fibres and flexible foams and PUs were applied on a limited scale as aircraft coating during World War II. Polyisocyanates became commercially available in 1952, production of flexible polyurethane foam began in 1954 using toluene diisocyanate and polyester polyols; these materials were used to produce rigid foams, gum rubber, elastomers. Linear fibers were produced from hexamethylene 1,4-Butanediol. In 1956 DuPont introduced polyether polyols poly glycol, BASF and Dow Chemical started selling polyalkylene glycols in 1957. Polyether polyols were cheaper, easier to handle and more water-resistant than polyester polyols, became more popular. Union Carbide and Mobay, a U. S. Monsanto/Bayer joint venture began making polyurethane chemicals. In 1960 more than 45,000 metric tons of flexible polyurethane foams were produced.
The availability of chlorofluoroalkane blowing agents, inexpensive polyether polyols, methylene diphenyl diisocyanate allowed polyurethane rigid foams to be used as high-performance insulation materials. In 1967, urethane-modified polyisocyanurate rigid foams were introduced, offering better thermal stability and flammability resistance. During the 1960s, automotive interior safety components, such as instrument and door panels, were produced by back-filling thermoplastic skins with semi-rigid foam. In 1969, Bayer exhibited an all-plastic car in Germany. Parts of this car, such as the fascia and body panels, were manufactured using a new process called reaction injection molding, in which the reactants were mixed and injected into a mold; the addition of fillers, such as milled glass and processed mineral fibres, gave rise to reinforced RIM, which provided improvements in flexural modulus, reduction in coefficient of thermal expansion and better thermal stability. This technology was used to make the first plastic-body automobile in the United States, the Pontiac Fiero, in 1983.
Further increases in stiffness were obtained by incorporating pre-placed glass mats into the RIM mold cavity known broadly as resin injection molding, or structural RIM. Starting in the early 1980s, water-blown microcellular flexible foams were used to mold gaskets for automotive panels and air-filter seals, replacing PVC polymers. Polyurethane foams have gained popularity in the automotive realm, are now used in high-temperature oil-filter applications. Polyurethane foam is sometimes made using small amounts of blowing agents to give less dense foam, better cushioning/energy absorption or thermal insulation. In the early 1990s, because of their impact on ozone depletion, the Montreal Protocol restricted the use of many chlorine-containing blowing agents, such as trichlorofluoromethane. By the late 1990s, blowing agents such as carbon dioxide, pentane, 1,1,1,2-tetrafluoroethane and 1,1,1,3,3-pentafluoropropane were used in North America and the EU, although chlorinated blowing agents remained in use in many developing countries.
Polyurethane products are called "urethanes", but should not be confused with ethyl carbamate, called urethane. Polyurethanes neither are produced from ethyl carbamate. Non-isocyanate based polyurethanes have been developed to mitigate health and environmental concerns associated with the use of isocyanates to synthesize polyurethanes. Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, phenolics. Polyurethanes are produced by reacting an isocyanate containing two or more isocyanate groups per molecule with a polyol containing on average two or more hydroxyl groups per molecule in the presence of a catalyst or by activation with ultraviolet light; the properties of a polyurethane are influenced by the types of isocyanates and polyols used to make it. Long, flexible segments, contributed by the polyol, give elastic polymer. High amounts of crosslinking give rigid polymers. Long chains and low crosslinking give a polymer, stretchy, short chains with lots of crosslinks produce a hard polymer while long chains and intermediate crosslinking give a polymer useful for making foam.
The crosslinking present in polyurethanes means that t
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its low melting temperature; the alloy constituents affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through, grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing. Carbon ranging from 1.8 to 4 wt%, silicon 1–3 wt% are the main alloying elements of cast iron. Iron alloys with lower carbon content are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram. Since the compositions of most cast irons are around the eutectic point of the iron–carbon system, the melting temperatures range from 1,150 to 1,200 °C, about 300 °C lower than the melting point of pure iron of 1,535 °C.
Cast iron tends to be brittle, except for malleable cast irons. With its low melting point, good fluidity, excellent machinability, resistance to deformation and wear resistance, cast irons have become an engineering material with a wide range of applications and are used in pipes and automotive industry parts, such as cylinder heads, cylinder blocks and gearbox cases, it is resistant to weakening by oxidation. The earliest cast-iron artifacts date to the 5th century BC, were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare and architecture. During the 15th century, cast iron became utilized for cannon in Burgundy, in England during the Reformation; the amounts of cast iron used for cannon required large scale production. The first cast-iron bridge was built during the 1770s by Abraham Darby III, is known as The Iron Bridge. Cast iron was used in the construction of buildings. Cast iron is made from pig iron, the product of smelting iron ore in a blast furnace.
Cast iron can be made directly from the molten pig iron or by re-melting pig iron along with substantial quantities of iron, limestone and taking various steps to remove undesirable contaminants. Phosphorus and sulfur may be burnt out of the molten iron, but this burns out the carbon, which must be replaced. Depending on the application and silicon content are adjusted to the desired levels, which may be anywhere from 2–3.5% and 1–3%, respectively. If desired, other elements are added to the melt before the final form is produced by casting. Cast iron is sometimes melted in a special type of blast furnace known as a cupola, but in modern applications, it is more melted in electric induction furnaces or electric arc furnaces. After melting is complete, the molten cast iron is poured into ladle. Cast iron's properties alloyants. Next to carbon, silicon is the most important alloyant. A low percentage of silicon allows carbon to remain in solution forming iron carbide and the production of white cast iron.
A high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, chromium, molybdenum and vanadium counteracts silicon, promotes the retention of carbon, the formation of those carbides. Nickel and copper increase strength, machinability, but do not change the amount of graphite formed; the carbon in the form of graphite results in a softer iron, reduces shrinkage, lowers strength, decreases density. Sulfur a contaminant when present, forms iron sulfide, which prevents the formation of graphite and increases hardness; the problem with sulfur is. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide; the manganese sulfide is lighter than the melt, so it tends to float out of the melt and into the slag. The amount of manganese required to neutralize sulfur is 1.7 × sulfur content + 0.3%. If more than this amount of manganese is added manganese carbide forms, which increases hardness and chilling, except in grey iron, where up to 1% of manganese increases strength and density.
Nickel is one of the most common alloying elements because it refines the pearlite and graphite structure, improves toughness, evens out hardness differences between section thicknesses. Chromium is added in small amounts to reduce free graphite, produce chill, because it is a powerful carbide stabilizer. A small amount of tin can be added as a substitute for 0.5% chromium. Copper is added in the ladle or in the furnace, on the order of 0.5–2.5%, to decrease chill, refine graphite, increase fluidity. Molybdenum is added on the order of 0.3–1% to increase chill and refine the graphite and pearlite structure. Titanium is added as a degasser and deoxidizer, but it increases fluidity. 0.15–0.5% vanadium is added to cast iron to stabilize cementite, increase hardness, increase resistance to wear and heat. 0.1–0.3% zirconium helps to form graphite and increase fluidity. In malleable iron melts, bismuth is added, on the scale of 0.002–0.01%, to increase how much silicon can be added. In white iron, boron is added to aid in the production of malleable iron.