Materials Handbook 15th 2010 Part 7 docx

burns with high flame speed and high heat. It is used to produce the boron hydrides such as decarborane, B 10 H 14 , or HH(H и BB и H) 5 HH, employed for boron fuels and for making boron plastics. Sodium boron hydride, a white, crystalline solid of composition NaBH 4 , made by reacting sodium hydride with methyl borate, is also used to produce the boranes for fuels. Triethyl borane, (C 2 H 5 )B, used for jet fuels and as a flame-speed accelerator, is a colorless liq- uid. It is spontaneously flammable, its vapors igniting with oxygen. Any element or chemical which causes spontaneous ignition of a rocket fuel is called a hypergolic material. Chemical radicals are potential high-energy fuels, as the recom- bining of them produces high specific impulses. But chemical radicals normally exit only momentarily and are thus not stable materials and, in general, are not commercial fuels. Ion propellants operate on the principle that like charges repel each other, and the fuel is an ion-plasma jet actually formed outside the engine. The original fuel is a metal such as cesium from which electrons can be stripped by pass- ing the vapor through a hot screen, leaving positive cesium ions, which are formed into a beam and exhausted from the jet thrust to be electronically neutralized in the ionized plasma. FULLERENES. Introduced by researchers at Rice University in the mid-1980s as large carbon molecules having 60 or more carbon atoms arranged in cagelike pseudospheres similar in shape to Buckminster Fuller’s geodesic dome and thus also called bucky balls. Carbon 60, or C 60 , molecules are a new form of carbon with potential for use in steel, catalysts, lubricants, superconductors, diamond synthesis, monocrystalline film, and as building blocks for high-strength poly- mers. At Argonne National Laboratory, C 60 has been used as a direct source of carbon to grow diamond film of ultrafine grain size some 6 times faster than by conventional methods. It eliminates the need for hydrogen and nitrogen and the chance of hydrogen contamination. The film is ultrasmooth even at thicknesses exceeding 390 ␮in (10␮m). Closely related to carbon fullerenes are carbon nanotabules, syn- thesized by graphite vaporization at NEC Corp. of Japan. They con- sist of concentric graphitic carbon capped with fullerenelike hemispheres that curve by incorporating five-member rings. The tips of the tabules can be opened by an oxidizing agent, creating nanoscale test tubes useful in studying catalysis and conducting experiments. At AT&T Bell Laboratories, researchers adding alkali metals to car- bon fullerenes created (NH 3 ) 4 Na 2 CsC 60 , a compound which converts from insulator to superconductor at Ϫ405°F (Ϫ243°C). Heating pitch- based carbon fibers in a nitrogen atmosphere at Japan Fine Ceramics Center has led to a class of fullerenes called carbon nanocapsules. Peeled off the fibers ultrasonically in acetone or alcohol and recovered 420 FULLERENES Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses as powder, they may serve as special lubricants and to protect mag- netic materials from oxidation. Noncarbon fullerenes, created at Iowa State University (Ames), comprise a nearly round outer cage of 70 or 74 indium atoms and successively smaller sodium and indium cages, with a single nickel, palladium or platinum atom in the center. By computer simulation, researchers at Japan’s National Institute of Materials and Chemical Research and Nissan Motor Co. have deter- mined the feasibility of creating fullerenelike nitrogen with 60 or 70 nitrogen atoms. Nitrogen 60, or N 60 , would resemble the C 60 struc- ture but not be stable. It could serve as a source for nitrogen gas and could be useful for rocket fuels and explosives. Rhondite and DiaSteel, commercial products of MicroMet Technology, are described as metallofullerite composites of iron encapsulated in a fullerene structure in the form of helix-wound, cablelike crystals. Rhondite 3591 contains 1.12% carbon, 0.89 silicon, 0.15 chromium, 0.12 manganese, and the balance iron. It has a modu- lus of elasticity of about 33ϫ10 6 lb/in 2 (228,000 MPa) and, as cast, a hardness of Rockwell C 27 and a compressive strength of 109,600 lb/in 2 (756 MPa). Hardening increases hardness to Rockwell C 62 and compressive strength to 338,900 lb/in 2 (2,337 MPa). The composite features exceptional wear resistance and exhibits self-healing, which improves with wear. DiaSteel is made from Rhondite by a process that converts a high percentage of the fullerenes to diamond. The diamond-embedded steellike structure has a hardness of Rockwell C 65 and is devoid of internal stresses. Further processing can remove the iron, leaving diamond crystals nanometers to a few micrometers in size, which can be used as abrasives or for electronic applications. FULLER’S EARTH. A soft, opaque clay with a greasy feel used as a fil- tering medium in clarifying and bleaching fats, greases, and mineral and vegetable oils. It absorbs the basic colors in the organic com- pounds. It is also used as a pigment extender and a substitute for tal- cum powder. It was formerly much used in the textile industry as a fuller for woolen fabrics, cleansing them by absorbing oil and grease. It is a hydrated compound of silica and alumina. It may contain 75% silica, 10 to 19 alumina, 1 to 4 lime, 2 to 4 magnesia, and sometimes ferric oxide. The usual color is greenish white to greenish brown. The rose-colored fuller’s earth from Florida is a variation of montmoril- lonite, (MgCa)O и Al 2 O 3 и 4SiO 2 . Florida’s fuller’s earth marketed by the Floridian Co. under the name of Floridin is a grayish-white material graded by sizes from B, which is 16 to 30 mesh, to XXX, which will pass 90% through a 200-mesh screen. Florex is this mate- rial processed by extrusion to increase the absorption capacity. A typi- cal analysis gives 58.1% silica, 15.43 alumina, 4.95 iron oxide, 2.44 magnesia, with small amounts of CaO, N 2 O, and K 2 O. The specific FULLER’S EARTH 421 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses gravity is 2.3. Florigel is the hydrated material which forms viscous suspensions in water, and it is used to replace bentonite as a filler for soaps, and for clarifying liquids. Diluex is finely powdered Florida fuller’s earth used as a diluent or a carrier for insecticides. Activated clay, or bleaching clay, for bleaching oils, may be acid- treated fuller’s earth, or it may be bauxite or kaolin. Florite, of Floridian Co., is activated bauxite. It is a red, granular, porous mate- rial of 20 to 60 mesh. FULMINATES. Explosives used in percussion caps and detonators because of their sensitivity. They may be called cap powder in car- tridge caps and detonators when used for detonating or exploding artillery shells. Mercury fulminate, Hg(CNO) 2 , a gray or brown, sandy powder, is the basis for many detonating compositions. It is made by the action of nitric acid on mercury and alcohol and is 10 times more sensitive than picric acid. It may be mixed with potas- sium chlorite and antimony sulfide for percussion caps. The fulmi- nates may be neutralized with a sodium thiosulfate. The azides are a group of explosives containing no oxygen. They are compounds of hydrogen or a metal and a monovalent N 3 radical. Hydrogen azide, HN 3 , or axoic acid, and its sodium salt are soluble in water. Lead azide, Pb(N 3 ) 2 , is used as a substitute for fulminate detona- tors. It is much more sensitive than mercury fulminate and in large crystals is subject to spontaneous explosion, but it is precipitated as a 93% pure product to suppress crystal formation and to form a free- flowing powder less sensitive to handling. Lead azide detonators for use in coal mining have copper detonators; all other blastings employ aluminum caps. Lead bromate, Pb(BO 3 ) 2 и H 2 O, is in col- orless crystals which will detonate if mixed with lead acetate. For primer caps, a substitute for mercury fulminate is a mixture of lead styphnate, lead triagoacetate, lead nitrate, and lead sulfocyanate. Lead styphnate, used as a detonator, is made by the sulfonation and nitration of resorcinol to form styphnic acid, or trinitroresor- cinol, (NO 2 ) 3 C 6 H(OH) 2 . This powder is treated with magnesia and with a lead nitrate solution to form the lead styphnate powder. Azoimide, or iminazoic acid, HN и N 2 , is an extremely explosive colorless gas liquefying at 99°F (37°C) which can be used in the form of its salts. Silver azoimide, AgN и N 2 , is highly explosive, and bar- ium azoimide, BaN 6 , explodes with a green flash. Cyanuric tri- azide is a powerful explosive made by reacting cyanuric chloride with sodium azide. Lead nitrate, a white, crystalline, water-soluble powder of composition Pb(NO 3 ) 2 , is used in match heads and explo- sive compositions. It is also employed as a mordant in dyeing and printing, and in paints. Nitrostarch, a primary high explosive, is used as a detonator and in caps. Mannitol hexanitrate is a color- 422 FULMINATES Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses less crystal that is used in blasting caps as a replacement for nitrostarch. FURFURAL. Also known as furfuraldehyde, furol, and pyromucic aldehyde. A yellowish liquid with an aromatic odor, having composi- tion C 4 H 3 O и CHO, specific gravity 1.161, boiling point 323°F (161.7°C), and flash point 132°F (56°C). It is soluble in water and in alcohol but not in petroleum hydrocarbons. On exposure it darkens and gradually decomposes. Furfural occurs in different forms in vari- ous plant life and is obtained from complex carbohydrates known as pentosans, which occur in such agricultural wastes as cornstalks, corncobs, straw, oat husks, peanut shells, bagasse, and rice. Furfural is used for making synthetic plastics, as a plasticizer in other syn- thetic resins, as a preservative, in weed killers, and as a selective sol- vent especially for removing aromatic and sulfur compounds from lubricating oils. It is also used for the making of butadiene, adiponi- trile, and other chemicals. Various derivatives of furfural are also used, and these, known col- lectively as furans, are now made synthetically from formaldehyde and acetylene which react to form butyl nedole. This is hydrogenated to butanediol, then dehydrated to tetrahydrofuran. Furan, or tetrol, C 4 H 4 O, used for plastics manufacture, is a colorless liquid boiling at 90°F (32°C). Methyl furan, or sylvan, C 4 H 3 O и CH 3 , is a colorless liq- uid boiling at 144°F (62°C). Tetrahydrofuran, (CH 2 ) 4 O, is a water- white liquid boiling at 151°F (66°C), having strong solvent powers on resins. It reacts with carbon monoxide to form adipic acid and is also an intermediate for the production of other chemicals. Quaker Oats converts tetrahydrofuran to polytetramethylene glycol, which is used for producing Spandex fibers, polyurethane elastomers, and other polymers. Polytetramethylene ether glycol, Du Pont’s Terathane, is a precursor of the company’s Lycra Spandex fiber and Hytrel copolyether-ester elastomers. Furfuryl alcohol, C 4 H 3 O и CH 2 OH, a yellow liquid with a brinelike odor, boiling at 349°F (176°C) with a flash point at 167°F (75°C), is used as a solvent for nitrocelu- lose and for dyes, and for producing synthetic resins. It is made by hydrogenation of furfural. Furfuryl alcohol resins, made by react- ing with an acid catalyst, are liquid materials that are low-cost and highly chemical-resistant. They are much used for protective coat- ings, tank linings, and chemical-resistant cements. They are dark in color. Alkor cement is a furfuryl alcohol solution which produces coatings resistant to chemicals and to temperatures to 380°F (193°C). Furacin is a nitro-furfural semicarbazone, a yellow crystalline pow- der made by nitrating furfural and reacting it with hydrazine hydrate. It is used as a bacterial treatment for wounds and burns. Furoic acid, or pyromucic acid, C 4 H 3 O и COOH, is a colorless crystalline FURFURAL 423 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses powder soluble in water. It is furan carboxylic acid used for mak- ing pharmaceuticals, flavors, and resins. Tetrahydrofurfuryl alcohol, (CH 2 ) 3 OCH и CH 2 OH, is the usual starting point for making furfuryl esters, ethers, and straight-chain compounds, and it is also a high-boiling solvent for gums, resins, and dyes. It is a liquid of specific gravity 1.064 boiling at 352°F (177.5°C), and is soluble in water. Furfural acetone, C 4 H 3 O и CH:CHCOCH 3 , is a reddish-brown liquid boiling at 444°F (229°C). Furfural, when treated with aniline at 302°F (150°C), forms an insoluble black furfural-aniline resin used in resistant protective coatings and enamels. Furfural-acetone resin, or furfuracetone, is a transpar- ent elastic resin made by the reaction of furfural and acetone in the presence of an alkali. Furfural also polymerizes with phenol to form furfuralphenol resins that are self-curing. They have high heat, chemical, and electrical resistance and excellent adhesion to metals and other materials, making them adaptable for chemical and electri- cal coatings. The resins have high gloss, but a very dark color. The Tygon resins of U.S. Stoneware Co. are furfural resins used for brush application as protective coatings for such purposes as chemical tank linings. They cure by self-polymerization, will withstand tem- peratures to 350°F (177°C), and are resistant to acids, alkalies, alco- hols, and hydrocarbons. Furafil, of Quaker Oats Co., is a by-product material containing modified cellulose, lignin, and resins, used as an extender for phenolic plywood glues, as an additive for phenolic mold- ing resins, and as a binder for foundry sand molds. Under the name of Fur-Ag, it is used as a conditioner and anticaking agent in fertil- izer mixtures. The material is a dark-brown, absorbent powder. Furane plastics have high adhesion and chemical resistance, but they do not have high dielectric strength, and are black or dark in color. They are used for pipe, fittings, and chemical equipment parts and for adhesives and coatings. Eonite is produced from Durez 16470, a furfural alcohol resin of Hooker Chemical. The pipe will resist hot acids and alkalies to 300°F (149°C), is strong, and does not sag in long lengths. Furfural-ketone resin is used to blend with epoxy laminating resins to reduce cost and improve the properties. FUSIBLE ALLOYS. Alloys having melting points below the boiling point of water 212°F (100°C). They are used as binding plugs in auto- matic sprinkler systems, for low-temperature boiler plugs, for solder- ing pewter and other soft metals, for tube bending, and for casting patterns and many ornamental articles and toys. They are also used for holding optical lenses and other parts for grinding and polishing. They consist generally of mixtures of lead, tin, cadmium, and bis- muth. The general rule is that an alloy of two metals has a melting point lower than that of either metal alone. By adding still other low- 424 FUSIBLE ALLOYS Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses fusing metals to the alloy, a metal can be obtained with almost any desired low melting point. The original Newton’s alloy contains 50% bismuth, 31.25 lead, and 18.75 tin. Newton’s metal, used as a solder for pewter, contains 50% bismuth, 25 cadmium, and 25 tin. It melts at 203°F (95°C) and will dissolve in boiling water. Lipowitz alloy, another early metal, contains 3 parts cadmium, 4 tin, 15 bismuth, and 8 lead. It melts at 158°F (70°C), is very ductile, and takes a fine polish. It was employed for casting fine ornaments, but now has many industrial uses. A small amount of indium increases the brilliance and lowers the melting point 34°F (19°C) for each 1% of indium up to a maximum of 18. Wood’s alloy, or Wood’s fusible metal, was patented in 1860 and was the first metal used for automatic sprinkler plugs. It contains 7 to 8 parts bismuth, 4 lead, 2 tin, and 1 to 2 cad- mium. It melts at 160°F (71°C), and this point was adopted as the operating temperature of sprinkler plugs in the United States; in England it is 155°F (68°C). The alloy designated as Wood’s metal by Cerro Metal Products Co. contains 50% bismuth, 25 lead, 12.5 tin, and 12.5 cadmium. It melts at 158°F (70°C). An early alloy for tube bending contains 50% bismuth, 16.7 lead, 13.3 tin, and 10 cadmium. It melts at 158°F (70°C) and can be easily removed from the tube after bending by dipping in boiling water or by applying steam. Cerrobend, or Bendalloy, of Cerro Metal Products Co., is a fusible alloy for tube bending which melts at 160°F (71°C). Cerrocast is a bismuth-tin alloy with pouring range of 280 to 338°F (138 to 170°C) and shrinkage of only 0.0001 in/in (0.0025 cm/cm), used for making pattern molds. Cerro-safe, or Safalloy, is a fusible metal used for toy-casting sets because the molten metal will not burn wood or cause fires. Alloys with very low melting points are sometimes used for this reason for pattern and toy casting. A fusible alloy with a melting point at 140°F (60°C) contains 26.5% lead, 13.5 tin, 50 bismuth, and 10 cad- mium. These alloys expand on cooling and make accurate impressions of the molds. Boiler-plug alloys have been made under a wide vari- ety of trade names with melting points usually ranging from 212 to 342°F (100 to 172°C). D’Arcet’s alloy, melting at 200°F (93°C), con- tains 50% bismuth, 25 tin, and 25 lead. Lichtenberg’s alloy, melting at 198°F (92°C), contains 50% bismuth, 30 lead, and 20 tin. Guthrie’s alloy has 47.4% bismuth, 19.4 lead, 20 tin, and 13.2 cadmium. Rose’s alloy contains 35% lead, 35 bismuth, and 30 tin. Homberg’s alloy, melting at 251°F (121°C), contains 3 parts lead, 3 tin, and 3 bismuth. Malotte’s metal, melting at 203°F (95°C), has 46% bismuth, 20 lead, and 34 tin. The variation of these different alloys is largely due to the relative cost of the different alloying metals at various times. Fusible metals have also been used in strip form to test the temperature of steels for heat-treating. The Temperite alloys are for this purpose with melting points between 300 and 625°F (149 and 329°C) in steps FUSIBLE ALLOYS 425 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses of 25°F (13.9°C). The Tempil pellets of Tempil Big Three Industries, Inc., are alloy pellets made with melting points in steps of 12.5, 50, and 100°F (6.9, 27.8, and 55.6°C) for measuring temperatures of 113 to 2500°F (45 to 1371°C). The Semalloy metals of Semi-Alloys Inc. cover a wide range of fusible alloys with various melting points. Semalloy 1010 with a melting point of 117°F (47°C) can be used where the melting point must be below that of thermoplastics. It con- tains 45% bismuth, 23 lead, 19 indium, 8 tin, and 5 cadmium. Semalloy 1280, for uses where the desired melting is near the boiling point of water, melts at 204°F (96°C). It contains 52% bismuth, 32 lead, and 16 tin. FUSTIC. Known also as Cuba wood. The wood of the tree Chlorophora tinctoria of tropical America, used for cabinetmaking and as a dyewood. It is yellow and very hard and has a fine, open grain. The density is about 41 lb/ft 3 (657 kg/m 3 ). The liquid extract of the wood produces the yellow dyestuff morin, C 15 H 1 i 1 O 7 , and the red dye morindone, C 15 H 11 O 5 . Fustic extracts are mordant dyes and give colors from yellow to olive with various mordants. Morin is used also as an indicator to detect aluminum, with which it devel- ops a green fluorescence. Young fustic, or Hungarian yellow- wood, is a yellow dyewood from Rhus cotinus. Osage orange, called bois d’arc, is the bright orangewood of the bush Maclura pomifera growing in the swamplands of Texas and Oklahoma. It has a high tannin content and is used in the textile and leather industries for orange-yellow and gold colors and to blend with greens. As a tanning agent, it may be blended with quebracho and chestnut extracts. GALLIUM. An elementary metal, symbol Ga, originally called aus- trium. It is silvery white, resembling mercury in appearance but hav- ing chemical properties more nearly like those of aluminum. It melts at 85.6°F (30°C) and boils at 4359°F (2403°C), and this wide liquid range makes it useful for high-temperature thermometers. Like bismuth, the metal expands on freezing, the expansion amounting to about 3.8%. Pure gallium is resistant to mineral acids and dissolves with difficulty in caustic alkali. It forms many salts at different valences. The weight is only about half that of mercury, having a specific gravity of 5.9. Commercial gallium has a purity of 99.9%. In the molten state it attacks other metals, and small amounts have been used in tin-lead solders to aid wetting and decrease oxidation, but it is expensive for this purpose. Gallium-tin alloy has been used when a low-melting- point metal was needed. It is also used as an electron carrier in silicon semiconductors, and crystals of gallium arsenide, GaAs, are used as semiconductors. Gallium arsenide can be used in rectifiers to operate to 426 FUSTIC Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses 600°F (316°C). The material has high electron mobility. This material in single-crystal bars is produced by Monsanto for lasers and modula- tors. GaAs is also used for lenses in CO 2 laser systems. Made under certain conditions, the material exhibits superconductivity at Ϫ440°F (Ϫ262°C). Gallium selenide, GaSe, gallium triiodide, GaI 3 , and other compounds are also used in electronic applications. Gallium exists in nature in about the same amount as lead, but it is widely dissipated and not found concentrated in any ore. It is found in small amounts associated with zinc ores and is recovered from smelter flue dust. In Germany it is produced as a by-product of copper smelting. It is also a minor constituent in the mineral sphalerite to the extent of 0.01 to 0.1%, and it occurs in almost all aluminum ores in the ratio of 0.11 to 0.22 lb (50 to 100 g) of gallium per ton of alu- minum. In the United States it is a by-product of aluminum produc- tion. About 1 oz (0.03 kg) of gallium is obtained commercially per ton (0.91 metric ton) of bauxite. GALLS. Tanning materials obtained from the nutgalls, or gall nuts, from the oaks of Europe and the Near East and from the sumac of China and Japan. Nutgalls are plant excrescences caused by the punctures of insects. They contain 50 to 70% tannins and are the richest in tannin of all the leather-tanning materials. The tannin is also valued for ink making and in medicine for treating burns. Green galls, Turkey galls, or Aleppo galls are obtained from the twigs of the Aleppo oak, Quercus infectoria, a shrub of the Near East. Those of blue color are the best quality, with green second, and white of infe- rior grade. Chinese galls, from the species of Rhus, are in the form of irregular, roundish nuts which enclose the insect. They show no vegetable structure but have a dense resinous fracture and are very high in tannin. The product known as gall in the pharmaceutical industry is an entirely unrelated material. It is beef gall, or ox bile, a bitter fluid from the livers of cattle. It is used for steroid production and in the tex- tile industry for fixing dyes and in soaps for washing dyed fabrics. Steroids, or hormones, made from ox bile, have a great number of possible combinations that have an influence on the behavior of the human cellular system. They are based on a four-ring, 17-carbon cyclopentamorphen anthrene nucleus, and arranging the side group in different ways gives compounds with distinct physiological properties. Cortisone, made by moving the oxygen atom of the steroid nucleus from the 12th to the 11th position, is one of the many steroids. Steroids are not synthesized from the more plentiful cholesterol, from the stig- mastrol of vegetable oils, or from the sapogenins of plants. Corticosteroids, inhaled from bronchodilators, are antiinflammatory medications for treating asthma. GALLS 427 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses GALVANIZED STEEL AND IRON. Galvanizing is the process of coating irons and steels with zinc for corrosion protection. The zinc may be applied by immersing the substrate in a bath of the molten metal (hot-dip galvanizing), by electroplating the metal on the substrate (electrogalvanizing), or by spraying atomized particles of the metal onto otherwise finished parts. The zinc protects the substrate in two ways: (1) as a barrier to atmospheric attack and (2) galvanically; that is, if the coating is broken, exposing the substrate, the coating will corrode sacrificially, or in preference to the substrate. From the stand- point of barrier protection alone, a coating weight of 0.82 lb/ft 2 (4 kg/m 2 ) on sheet steel will provide a service life of about 30 years in rural atmosphere and about 5 years in severe industrial atmosphere. Both hot-dip galvanizing and electrogalvanizing are continuous processes applied in the production of galvanized steel, and the coating may be applied on one or both sides of the steel. In the case of hot-dipped galvanized steel, the zinc at the steel face alloys with about 25% iron from the steel. Iron alloying decreases progres- sively to a region that is 100% zinc. The amount of coating is com- monly indicated by designations G235 to G01 for regular zinc coatings and A60 to A01 for zinc-iron coatings. The numbers in the designations denote the minimum total coating weight on both sides of the sheet as determined by dissolving the zinc from sam- ples of the sheet, usually at three locations (triple-spot test), and weighing it. For example, G210 refers to a total coating weight of 2.10 oz/ft 2 (640 g/m 2 ), that is, 1.05 oz/ft 2 (320 g/m 2 ) per side or, in thickness, 0.0017 in (0.04 mm) per side. The lower the number in these designations, the lesser the amount of zinc. Electro- galvanized steel typically has a more homogeneous but thinner coating of pure zinc and is somewhat more formable than the hot- dipped variety. A spangled surface has long been characteristic of traditional hot- dipped galvanized steel. Although that effect can be minimized, con- cern by automakers that the spangles might show through on painted external body panels gave rise to the development of Zincrometal in the early 1970s and increased use of electrogalvanized steel. Zincrometal, developed by Diamond Shamrock and now a product of Metal Coatings International, is one-side-coated sheet steel produced on coil-coating lines. The coating consists of a chromate base coat and a special zinc-rich top coat. Total coating thickness is about 0.0005 in (0.00002 mm). However, it serves only as a barrier coating and does not provide sacrificial, or galvanic, protection. Through the 1970s, it was produced under license by virtually all major sheet-steel produc- ers serving the auto industry, but its use has declined since the late 1970s as steel producers developed hot-dipped galvanized steels hav- ing more uniform surface appearance. 428 GALVANIZED STEEL AND IRON Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses The American Iron and Steel Institute lists eight types of galvanized steel for auto applications in addition to Zincrometal. Five are of the hot-dipped variety: (1) regular and minimum spangle; (2) fully alloyed zinc-iron coated; (3) differentially zinc-coated (both sides coated but one side having a substantially lower weight, or thickness, of zinc than the other); (4) differentially zinc-iron-coated (same as differentially zinc-coated except that the side with the thin coating is heat-treated or wiped to produce a fully alloyed zinc-iron coating); and (5) one-side- coated (one side is zinc-free). The three types of electrogalvanized sheet steels are (1) electrolytic flash-coated [0.10 to 0.20 oz/ft 2 (30 to 60 g/m 2 ) on both sides for minimal corrosion protection]; (2) electro- plated zinc-coated [coated on one or both sides, the latter with equal or differential coating weights, with as much as 0.65 oz/ft 2 (200 g/m 2 ) total coating], and (3) electroplated iron-zinc-coated (coated on one or both sides, the latter with equal or differential coating weights, by simulta- neous electroplating of zinc and iron to form an alloy coating). Among the recently developed hot-dipped galvanized steels having improved surface quality is National Steel’s Unikote, a one-side-coated steel made by first differentially coating cold-rolled steel on a hot-dip galvanizing line and then electrolytically treating the steel to remove the minimal coating on one side while simultaneously depositing an equal amount on the thicker-coated side. Another “one-side” is Armco’s Zincgrip O.S., which is coated by a meniscus roll precisely positioned just above the molten bath in a chamber. The chamber, sealed in the bath, contains high-purity nitrogen. When the steel approaches the bath surface, a meniscus forms across its width, supported only by surface tension. There is no tendency for the zinc to move onto the backside unless the steel is immersed substantially below the bath surface. The nitrogen, from a finishing jet within the chamber, impinges on the steel while the zinc is still molten, regulating coating thickness and uniformity. Because of the protective atmosphere, the steel is virtually free of surface defects. Galva-One, a one-side electro- galvanized steel developed by U.S. Steel, has a zinc coating of 0.32 oz/ft 2 (97 g/m 2 ) or 0.00054 in (0.014 mm). Bethlehem Steel’s Automotive Jetcoat is an iron-zinc galvan- nealed sheet steel coated with less than normal amounts of zinc. It is said to enhance paint appearance and resistance welding but at a sacri- fice in corrosion protection. It consists of a light iron-zinc alloy coating and a thin overlay of zinc on both sides. Inland Steel’s Paint-Tite B, which has a 0.32 oz/ft 2 (97 g/m 2 ) coating on one side and a 0.00015-in (0.0038-mm) zinc-iron-alloy coating on the other, provides good corro- sion resistance and paint appearance. Armco’s latest two-side galva- nized steel, Zincgrip Ultrasmooth, like Zincgrip O.S., is coated in a nitrogen atmosphere for improved surface quality. The steel is then sprayed with a steam mist containing ammonium phosphate to produce GALVANIZED STEEL AND IRON 429 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Materials, Their Properties and Uses [...]... workable gold alloys is 0 .7% A gold-gallium alloy with 2.5% gallium has a resistivity of 90 ⍀/cir mil ft (15 ϫ 10 Ϫ8 ⍀ и m), a tensile strength of 55,000 lb/in2 ( 379 MPa), and 22% elongation Gold powder and gold sheet, for soldering semiconductors, are 99.999% pure The gold wets silicon easily at a temperature of 70 0°F ( 371 °C) Chemically reduced powder is amorphous and comes in particle sizes of 39 to... Generally speaking, strength increases directly in relation to the amount of glass A part containing 80% by weight glass and 20 resin is almost 4 times stronger than a part containing the opposite amounts of these two materials Chemical, electrical, and thermal performance is influenced by the resin system used as the matrix Materials selection, Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)... oxygenates into gasoline is now required during winter months in many states with high ambient levels of carbon monoxide emissions Using gasoline with 2 .7% oxygen by weight reduces these emissions by 15 to 20% The 2 .7% is typically met by blending 7. 7% ethanol or 15 MTBE by volume California, however, limits oxygen to 2% so as not to increase emissions of nitrogen oxides There are problems, however,... sorghum, and black locust, or Robina pseudoacacia, which grows rapidly The common commercial gasolines in the United States had an upper limit at 4 37 F (225°C) and an average specific gravity of 0 .75 , with the aromatic-free gasolines having a specific gravity of 0 .71 8 Aviation gasoline formerly had a boiling range below 302°F (150°C), but aviation gasolines are now the high-octane cracked and treated gasolines... Air Act, passed in 1 970 , requires the use of unleaded gasoline in all motor vehicles built in 1 975 or later To attain the minimum of 91 octane in unleaded gas, as Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Materials, Their Properties... binders for fibrous materials Haveg 16 075 , of Haveg Industries, Inc., a gasketing sheet to withstand hot oils and superoctane gasolines, is based on Viton, of Du Pont, a copolymer of vinylidene fluoride and hexafluoropropylene It contains about 65% fluorine, has a tensile strength of 2,000 lb/in2 (14 MPa) with elongation of 400%, and withstands operating temperatures to 400°F GASKET MATERIALS Downloaded... use is subject to the Terms of Use as given at the website Materials, Their Properties and Uses 436 GELATIN oil But gasolines are also produced from the high-volatile bituminous coal The low-grade fuel bituminous coals contain a high proportion of anthraxylon, or vitrain, which is that part of bituminous coal consisting of undisintegrated parts of trees and plants This structure of coal has less carbon... temperatures to 1600°F ( 871 °C) without losing its strength or clarity It will withstand temperatures to 1800°F (982°C) but becomes cloudy and opaque The glass has high thermal shock resistance Filter glass is flat, porous glass sheets or disks to replace high-alloy metals for filtering chemicals Filter disks come in five porosities, from A, with pore diameters of 5 ,71 0 to 6,890 ␮in (145 to 175 ␮m), to E, with... (1 to 4␮m) thick and 0.03125 in (0. 079 cm) in diameter In paints it produces a tilelike appearance Carboglas 1600 is a coating material of a chemically resistant polyester solution containing glass flake When sprayed, a 0.030-in (0. 076 -cm) coating will contain 120 layers of the thin glass flake Filmglas is glass flake in tiny platelets The 10- to 18-mesh flake is 78 ␮in (2 ␮m) thick Glass powder, used... It has a compressive strength of 100 lb/in2 (0.69 MPa) and a flexural strength of 75 lb/in2 (0.5 MPa) and will retain rigidity to 800°F (4 27 C) Low-melting-point glass, for encapsulating electronic components, is made by adding selenium, thallium, arsenic, or sulfur to give various melting points from 260 to 660°F (1 27 to 349°C) These glasses can be vaporized and condensed as thin films Some are insulators, . carbon monoxide emissions. Using gasoline with 2 .7% oxygen by weight reduces these emissions by 15 to 20%. The 2 .7% is typically met by blending 7. 7% ethanol or 15 MTBE by volume. California, however,. C 4 H 3 O и CH 2 OH, a yellow liquid with a brinelike odor, boiling at 349°F ( 176 °C) with a flash point at 1 67 F (75 °C), is used as a solvent for nitrocelu- lose and for dyes, and for producing. first metal used for automatic sprinkler plugs. It contains 7 to 8 parts bismuth, 4 lead, 2 tin, and 1 to 2 cad- mium. It melts at 160°F (71 °C), and this point was adopted as the operating temperature