aluminum usually have a high proportion of lead oxide to lower the melting point, and enamels for magnesium may be based on lithium oxide. Some enamels for low-melting-point metals have the ceramic frit bonded to the metal with monoaluminum phosphate at temperatures as low as 400°F (204°C). The mineral oxide coatings fused to metals are often called porce- lain enamels, but they are not porcelain, and the term vitreous enamel is preferred in the industry, although ceramic-lined tanks and pipe are very often referred to as glass-lined steel. The composi- tion varies greatly, one company having more than 3,000 formulas. Vitreous enameled metals are used for cooking utensils, signs, chemi- cal tanks and piping, clock and instrument dials, and siding and roof- ing. Ground coats are usually no more than 0.004 in (0.010 cm) thick, and cover coats may be 0.003 to 0.008 in (0.006 to 0.020 cm) thick. The hardness ranges from Knoop 150 to 500. Thick coatings on thin metals are fragile, but thin coatings on heavy metals are flexible enough to be bent. Standard porcelain-type enamel has a smooth, glossy surface with a light reflectance of at least 65% in the white color, but pebbly surfaces that break up the reflected image may be used for architectural applications. High-temperature coatings may contain a very high percentage of zirconium and will withstand temperatures to 1650°F (899°C). Refractory enamels, for coating superalloys to protect against the corrosion of hot gases to 2500°F (1371°C), may be made with stan- dard ceramic frits to which is added boron nitride with a lithium chromate or fluoride flux. Blue undercoats containing cobalt are gen- erally used to obtain high adhesion on iron and steel, but some of the enameling steels do not require an undercoat, especially when a specially compounded frit or special flux is used. When sodium alu- minum silicate, Na 2 O и Al 2 O 3 и 6SiO и xH 2 O, is used instead of borax, a white finish is produced without a ground coat. Mirac is a white enamel which gives good adhesion directly to steel. Enamels contain- ing titanium oxide will adhere well to steels alloyed with a small amount of titanium. Ti-Namel, of Inland Steel Co., is an enameling steel containing titanium. Many trade names are applied to vitreous enamels and to enameled metals. Vitric steel is an enameled corrugated sheet steel for con- struction. Majolica is an old name for marblelike enamels made by mixing enamels of different colors, but mottled graywear is made with cobalt oxide on steel that has a controlled misting on the surface. Cloisonné enamel is an ancient decorative enamel produced by sol- dering thin strips of gold on the base metal to form cells into which the colored enamel is pressed and fused into place. It requires costly hand methods and is now imitated in synthetic plastics under names such as Enameloid. 350 ENAMEL 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 word enamel in the paint industry refers to glossy varnishes with pigments or to paints of oxide or sulfate pigments mixed with var- nish to give a glossy face. They vary widely in composition, in color and appearance, and in properties. As a class, enamels are hard and tough and offer good mar and abrasion resistance. They can be formulated to resist attack by the most commonly encountered chemical agents and corrosive atmospheres. Because of their wide range of useful proper- ties, enamels are one of the most widely used organic finishes in indus- try and are especially used as household appliance finishes. Japan is a name applied to black baking enamels. Japan consists of a pigment, a gum, a drying oil, and a reducer, the same as any oil enamel. It is always baked, which drives off the solvent and fuses the gum into a uni- form vitreous layer. Japans have now been replaced by synthetic baking finishes. The modified phenolmelamine and alkyd-melamine synthetic resins produce tough and resistant enamel coatings. Quick-drying enamels are the cellulose lacquers with pigments. Fibrous enamel, used for painting roofs, is an asphalt solution in which asbestos fibers have been incorporated. When of heavy consistency and used for caulk- ing metal roofs, it is called roof putty. EPOXY RESINS. A class of synthetic resins characterized by having in the molecule a highly reactive oxirane ring of triangular configura- tion consisting of an oxygen atom bonded to two adjoining and bonded carbon atoms. They are usually made by the reaction of epichlorohy- drin with phenol compounds, but epoxidation is also done by the oxi- dation of a carbon-to-carbon double bond with an organic peracid such as peracetic acid. Epichlorohydrin is produced from allyl chloride and is a colorless liquid with a chlorine atom and an epoxide ring. The dipoxy resins made by the oxidation of olefins with peracetic acid have higher heat resistance than those made with bisphenol. Epoxidation is not limited to the making of plastic resins, and epoxi- dized oils, usually epoxidized with peracetic acid, are used as paint oils and as plasticizers for vinyl resins. Epoxy resins are generally more costly than many other ther- mosetting resins, but, because of their combinations of high mechan- ical and electrical properties, they are important, especially for such uses as adhesives, chemically resistant coatings, and encapsulation of electronic units. The resins are thermosetting and inert. For encap- sulation, they cast easily with little shrinkage. They have very high adhesion to metals and nonmetals, heat resistance from 350 to 500°F (177 to 260°C), dielectric strength to 550 V/mil (22 V/m), and hardness to Rockwell M 110. The tensile strength may be up to 12,000 lb/in 2 (83 MPa), with elongation to 2 to 5%, but some resilient encapsulating resins are made with elongation to 150% EPOXY RESINS 351 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 with lower tensile strengths. The resins have high resistance to common solvents, oils, and chemicals. An unlimited variety of epoxy resins are possible by varying the basic reactions with different chemicals or different catalysts, or both, by combination with other resins, or by cross-linking with organic acids, amines, and other agents. To reduce cost when used as laminating adhesives, they may be blended with furfural resins, giving adhesives of high strength and high chemical resistance. Blends with polyamides have high dielectric strength, mold well, and are used for encapsulating electrical components. By using a polyamide curing agent an epoxy can be made water-emulsifiable for use in water-based paints. An epoxy resin with 19% bromine in the molecule is flame-resistant. Another grade, with 49% bromine, is a semisolid, used for heat-resistant adhesives and coatings. Epoxidized polyolefins have five or more reactive epoxy groups along each molecule of the chain instead of the usual two terminal epoxy groups on each molecule. With dibasic acids or anhydrides they form strong, hard resins of high heat resistance; or resins of lower viscosity are made for laminating and casting. Epoxy resins made by the reaction of epichlorohydrin with a phenol-formaldehyde resin with an anhydride catalyst have heat distortion points of 570°F (300°C). As an adhesive for laminates, they give very high strength at elevated temperatures. Epoxies can be copolymerized with other resins. Epoxy-acrylate resin, used for glass-fiber laminates, com- bines the resistance and adhesiveness of the epoxy with the fast cure and strength of the acrylate. Epoxy resins can be made with cyclopentyl oxide terminal groups instead of diglycidyl ether. The yield strength at 392°F (200°C) is 18,200 lb/in 2 (123 MPa), and they have a heat deflection temperature of 434°F (223°C). Epoxy resins can be produced by a reaction of hydantoin with epichlorohydrin. Hydantoin is a nitrogen-containing heterocyclic compound. They have high mechanical properties, good dielectrical characteristics, and ultraviolet light resistance. They retain light transmission properties after thermal aging of several thousand hours at 302°F (150°C). Epoxy has been the major matrix material of polymer-matrix composites for aircraft applications for many years. This is attribut- able to ease of processing (low-pressure, moderate-temperature auto- clave or press curing), good mechanical properties, and low cost. The principal reinforcements are fibers of aramid (Kevlar), boron, glass, and graphite. In such applications, the composites are used for service temperatures up to about 300°F (149°C). In recent years, however, 352 EPOXY RESINS 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 some aircraft manufacturers have replaced epoxy with bis- maleimides, which process much as epoxy does and can be used at service temperatures up to about 350°F (177°C). Prepreg 977, of ICI Fiberite, is an epoxy toughened with a proprietary thermoplastic elas- tomer so as not to sacrifice compression strength while increasing toughness. Unlike some elastomer-modified grades, the elastomer is an integral part of the resin so that it unites in the epoxy backbone on curing. Compression-after-impact strength and wet-service tempera- tures range from 47,000 lb/in 2 (324 MPa) and 180°F (82°C) for 977-1 to 30,000 lb/in 2 (207 MPa) and 250°F (121°C) for 977-3. Shell Chemical’s Epon HPT 1077 epoxy is an amine-based compound, which combines low viscosity with good mechanical properties and chemical and heat resistance. At 77°F (25°C), viscosity is about 3,500 cP, one-fourth that of Epon 828. It also has a glass transition temperature of 500°F (260°C), which is high for a low-viscosity resin. PR-500, of 3M, is a one-part compound that can resist temperatures up to 350°F (177°C). Reinforced with 50% glass fiber, it is used for resin-transfer-molded vent louvers of auxiliary power units on large commercial aircraft. FR-4 is a halogenated epoxy compound widely used for printed-circuit boards. Novoloids are fibers containing at least 85%, by weight, cross- linked novalac epoxies. Kynol is a novoloid noted for its exception- ally high temperature resistance. At 1920°F (1049°C) the fiber is virtually unaffected. The fiber also has high dielectric strength and excellent resistance to all organic solvents and nonoxidizing acids. Shell Chemical’s Epon HPT 1050 epoxy is a novalac compound in semisolid neat resin form or as a 75% by weight solution in acetone. Epon 861 epoxy is a bisphenol F low-viscosity compound for resin- transfer molding or use as an adhesive. Eposert, of Ciba Geigy, is a line of epoxy syntactic inserts for reinforcing honeycomb. SynSpand, of Dexter Aerospace, is a line of epoxy-based, expandable syntactic films. A family of one-component epoxy resins, named Arnox, was devel- oped by General Electric Co. Suitable for compression, transfer, injection molding, filament winding, and pultrusion, they cure rapidly at temperatures of 250 to 350°F (121 to 177°C). The compres- sion and transfer-molding grade is a black, mineral-filled compound. The injection-molding grade is a pelletized glass-fiber-reinforced compound with a shelf life of 9 to 12 months below 80°F (27°C). ESSENTIAL OILS. Aromatic oils found in uncombined form in various parts of plants and employed for flavors, perfumes, disinfectants, ESSENTIAL OILS 353 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 medicines, and stabilizers; for masking undesirable odors; and as raw materials for making other products. They are usually the esters upon which the odiferous properties of the plants depend, and they are called essential oils because of their ease of solubility in alcohol to form essences. They are also called volatile oils, although this term is sometimes also applied to the light and volatile distillates from petroleum. The essential oils are of four general classes: the pinenes or terpenes of coniferous plants, containing carbon and hydrogen of the empirical formula C 10 H 16 , such as oil of turpentine; oxygenated oils containing carbon, hydrogen, and oxygen, such as oil of cassia; nitrogenated oils containing carbon, hydrogen, oxygen, and nitrogen, such as oil of bitter almonds; sul- furated oils containing carbon, hydrogen, and sulfur, such as oil of mustard. Although fixed vegetable oils are obtained by expression, the essen- tial oils are obtained by distilling the buds, flowers, leaves, twigs, or other parts of the plant. Rose oil is found only in the flowers. Orange oil and lemon oil are from the flowers and the fruits, but are of different compositions. Sweet birch oil and cinnamon oil are from the bark. Valerian and calamus are only in the roots, while sandalwood oil and cedar oil are only in the wood. Sometimes the essential oil is not in the plant, but is developed when the plant is macerated with water. The alpha pinene extracted from turpentine is used for paints and varnishes because it has a high evaporation rate. It is a water-white liquid of pleasant odor boiling at 325°F (163°C). It is also used in the synthesis of camphor. Pinic acid is a complex carboxycyclobutane acetic acid produced from alpha pinene. Its esters are used for synthetic lubricants. Balsams are solid or semisolid resinous oils and are mixtures of resins with cinnamic or benzoic acid, or both, with sometimes another volatile oil. They are obtained from a variety of trees and are used in antiseptics, perfumes, flavors, and medicine. Some of the essential oils contain alkaloids which have a physiological effect. Wormwood oil, distilled from the dried leaf tops of the perennial herb Artemisia absinthium, native to southern Europe but also grown in the United States, is used in medicine for fevers, and for flavoring the liqueur absinthe. The drug santonin, used for worm treatment for ani- mals, is an alkaloid extracted from the unopened flower heads of the Levant wormseed, A. cina, of the Near East, but wormseed oil, or Baltimore oil, used for the same purpose, is an essential oil containing the alkaloid ascoridole. It is distilled from the seeds and leaf stems of the annual plant Chenopodium anthelminticum, grown in Maryland. 354 ESSENTIAL OILS 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 ESTERS. Combinations of alcohols with organic acids, which form sev- eral important groups of commercial materials. The esters occur natu- rally in vegetable and animal oils and fats as combinations of acids with the alcohol glycerin. The natural fats are usually mixtures of esters of many acids, coconut oil having no less than 14 acids. Stearic, oleic, palmitic, and linoleic acid esters are the common bases for most vegetable and animal fats, and the esters of the other acids such as linolenic, capric, and arachidic give the peculiar characteristics of the particular fat, although the physical characteristics and melting points may be governed by the basic esters. Esters occur also in waxes, the vegetable waxes being usually found on the outside of leaves and fruits to protect them from loss of water. The waxes differ from the fats in that they are combinations of monacids with monohydric, or simple, alcohols, rather than with glycerin. They are harder than fats and have higher melting points. Esters of still lower molecular weights are also widely distributed in the essential oils of plants where they give the characteristic odors and tastes. All the esters have the characteristic formula ArCOOR or RCOOR, where R represents an alkyl group, and Ar an aryl group, that is, where R is a univalent straight-chain hydro- carbon having the formula C n H 2nϩ1 and Ar is a univalent benzene ring C 6 H 5 . In the esters of low molecular weight which make the odors and flavors, the combination of different alcohols with the same acid yields oils of different flavor. Thus the ester methyl acetate, CH 3 COOCH 3 , is peppermint oil; amyl acetate, CH 3 COOC 5 H 11 , is banana oil; and isoamyl acetate, CH 3 COO(CH 2 ) 3 (CH 3 ) 2 , is pear oil. Esters are used as solvents, flavors, perfumes, waxes, oils, fats, fatty acids, pharmaceuti- cals, and in the manufacture of soaps and many chemicals. Ester liquid lubricants have good heat and oxidation resistance at high tempera- tures and good fluidity at low temperatures. They are widely used in jet aircraft. The natural esters are recovered by pressing or extraction, and steam distillation. Synthetic esters are prepared by reacting an alcohol with an organic acid in the presence of a catalyst, such as sulfuric acid or para- toluenesulfonic acid. The product is purified with an azeotrope, such as benzene or toluene. A range of cellulose acetate esters are made by esterification of cellulose with acetic anhydride. Cellulose nitrate ester is obtained by reacting cellulose with nitric acid, cellulose sulfate from chlorosulfonic acid in pyridine solvent, and cellulose phosphate from phosphoric acid in molten urea. Alkoxysilanes are silicon esters in which the silicon is connected to an organic group by oxygen. Tetraethoxysilane, a low-molecular-weight compound, is reactive and is used in binders, resins, and glasses and as a cross-linking agent. ESTERS 355 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 Tetrabutoxysilane is more stable and is used in lubricants and heat- transfer fluids. Ester alcohols are intermediates that require less acid for esterifi- cation. Texanol, of Eastman Chemical Co., has both a hydroxy group and an ester linkage with the empirical formula C 12 H 24 O 3 . It produces a wide range of chemicals and compounds with low, Ϫ71°F (Ϫ57°C), pour point. ETCHING MATERIALS. Chemicals, usually acids, employed for cut- ting into, or etching, the surface of metals, glass, or other material. In the metal industries they are called etchants. The usual method of etching is to coat the surface with a wax, asphalt, or other sub- stance not acted upon by the acid; cut the design through with a sharp instrument; and then allow the acid to corrode or dissolve the exposed parts. For etching steel, a 25% solution of sulfuric acid in water or a ferric chloride solution may be used. For etching stain- less steels, a solution of ferric chloride and hydrochloric acid in water is used. For high-speed steels, brass, or nickel, a mixture of nitric and hydrochloric acids in water solution is used, or nickel may be etched with a 45% solution of sulfuric acid. Copper may be etched with a solution of chromic acid. Brass and nickel may be etched with an acid solution of ferric chloride and potassium chlo- rate. For red brasses, deep etching is done with concentrated nitric acid mixed with 10% hydrochloric acid, the latter being added to keep the tin oxide in solution and thus retain a surface exposed to the action of the acid. For etching aluminum a 9% solution of cop- per chloride in 1% acetic acid, or a 20% solution of ferric chloride may be used, followed by a wash with strong nitric acid. Sodium hydroxide, ammonium hydroxide, or any alkaline solutions are also used for etching aluminum. Zinc is preferably etched with weak nitric acid, but requires a frequent renewal of the acid. Strong acid is not used because of the heat generated, which destroys the wax coating. A 5% solution of nitric acid will remove 0.002 in (0.005 cm) of zinc per minute, compared with the removal of over 0.005 in (0.013 cm) per minute in most metal-etching processes. Glass is etched with hydrofluoric acid or with white acid. White acid is a mixture of hydrofluoric acid and ammonium bifluoride, a white crystalline material of composition (NH 4 )FHF. Sodium chlorate may be used as the electrolyte in producing chemical finishes. The process in which the metal is removed chemically to give the desired finish as a substitute for mechanical machining is called chemical machining. 356 ETCHING MATERIALS 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 To trace the electrical circuit pathways on silicon chips and printed-circuit boards, liquid etchants containing acids are used. Buffered hydrofluoric acid is a selective etchant for silicon diox- ide in the presence of silicon. Ammonium fluoride is a common buffer, and its concentrations in the mixture range from 20% to more than 90. Formulations containing combinations of nitric, acetic, phosphoric, and sulfuric acids are called mixed-acid etchants. Ammonium chloride, ammonium persulfate, and cupric chlo- ride are used for etching copper printed-circuit boards. Ceric ammonium nitrate is suited for etching silicon wafers. Dry etch- ing, carried out in the gas phase, employs silicon tetrafluoride and carbon tetrafluoride. ETHER. The common name for ethyl ether, or diethyl ether, a highly volatile, colorless liquid of composition (C 2 H 5 ) 2 O made from ethyl alcohol. It is used as a solvent for fats, greases, resins, and nitrocellulose, and in medicine as an anesthetic. The specific gravity is 0.720, boiling point 93.6°F (34.2°C), and freezing point Ϫ177°F (Ϫ116°C). Its vapor is heavier than air and is explosive. Actually, ether is a more general term, and an ether is an alkyl oxide with two alkyl groups joined to an oxygen atom. The ethyl ether would thus be expressed as C 2 H 5 и O и C 2 H 5 , and there are many ethers. Butyl ether, (C 4 H 9 ) 2 O, has a much higher boiling point, 284°F (140°C); is more stable; and is used as a solvent for gums and resins. Isopropyl ether, (CH 3 ) 2 CHOCH(CH 3 ) 2 , is a by-product in the man- ufacture of isopropyl alcohol from propylene. It has a higher boiling point than ethyl ether, 156°F (69°C); lower solubility in water; and is often preferred as an extractive solvent. Methyl ether, or dimethyl ether, also known as wood ether, is a colorless gas of composition (CH 3 ) 2 O, with a pleasant aromatic odor. The boiling point is Ϫ10.3°F (Ϫ23.5°C). The specific gravity is 1.562 or, as a liq- uid compressed in cylinders, 0.724. It is used for fuel, as a welding gas, as a refrigerant, and for vapor-pressure thermometers. Hexyl ether, C 6 H 13 OC 6 H 13 , has a high boiling point, 439°F (226°C); very low water solubility; and a specific gravity of 0.7942. It is stable and not volatile, with a flash point of 170°F (77°C). It is used in foam breakers and in chemical manufacture where anhydrous properties are desired. A low-boiling-point chemical used as an extractive sol- vent and for plastics because of its stability in alkalies and its high water solubility is methylal, CH 3 OCH 2 OCH 3 . It is a water-white liquid boiling at 108°F (42.3°C). Ether reacts slowly with the oxygen of air to form highly explosive and poisonous compounds, so that long-stored ether is dangerous for use as an anesthetic. ETHER 357 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 ETHYL ALCOHOL. Also called methyl carbinol, and ethanol when made synthetically. It is the common beverage alcohol, which when denatured for nonbeverage purposes is called industrial alcohol. About 90% of the ethyl alcohol used in the United States is dena- tured. Ethyl alcohol is a colorless liquid with a pleasant odor but burning taste. The composition is CH 3 CH 2 OH, specific gravity 0.79, boiling point 173.3°F (78.5°C), and freezing point Ϫ179°F (Ϫ117.3°C). It mixes with water in all proportions and takes up mois- ture from the air. It burns with a bluish flame and high temperature, yielding carbonic acid and water. The ignition temperature is 965°F (518°C). It is one of the best solvents and dissolves many organic materials such as gums, resins, and essential oils, making solutions called essences. Alcohol is sold by the proof gallon, with 100 proof containing 50% alcohol by volume and having a specific gravity of 0.7939. The term alcohol, alone, refers to 188 to 192 proof. High-purity alcohol, grain alcohol, and pure ethyl alcohol are terms for 190 proof. Absolute alcohol, or anhydrous alcohol, is 200 proof, free of water. Methylated spirits is a term first used in England to desig- nate the excise-free mixture of 90% ethyl alcohol and 10 wood alco- hol for industrial use. Denatured ethyl alcohol, made unsuitable for beverage purposes, may be marketed under trade names such as Synasol of Union Carbide. Solox consists of 100 parts 190-proof alcohol, 5 ethyl acetate, and 1 gasoline, used for lacquers, fuel, and as a solvent. Neosol, of Shell Chemical Corp., is 190-proof ethyl alcohol denatured with four parts of a mixture of tertiary butyl alco- hol, methyl isobutyl ketone, and gasoline. Ethyl alcohol is used as a solvent in varnishes, explosives, extracts, perfumes, and pharmaceuticals; as a fuel; as a preserving agent; as an antifreeze; and for making other chemicals. Up to 15% of alcohol can be used in gasoline motor fuels, called generically by the name gasohol, without change in carburetion. M85, sold in the western United States, is methanol with 15% alcohol. Brazil produces large quantities of Proalcohol, which contains 22% anhydrous ethanol. The German motor fuel Monopolin was a mixture of absolute alcohol and benzene. Ethyl alcohol is classified as a poison when pure, but is employed as a beverage in many forms. In small quantities it is an exhilarant and narcotic. In all countries large amounts of beverage alcohol are made from starches, grains, and fruits, retaining the original flavor of the raw material and marketed directly as wines, whiskies, and brandies. But synthetic wines are made by ferment- ing sugar and adding vegetable extracts to supply flavor and bouquet. No methyl alcohol or fuel oil is produced in the process. Alcohol is pro- duced easily by the fermentation of sugars, molasses, grains, and 358 ETHYL ALCOHOL 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 starch. It is also made cheaply by directly or indirectly hydrating eth- ylene produced by the cracking of petroleum hydrocarbons. In Europe it is also made from the waste liquor of pulp mills by fermentation of wood sugar. Sulfite pulp liquor contains 1.8% fermentable hexose sugar. It is also made directly from wood waste by fermenting the wood sugar molasses. Ethanol is concentrated and purified by extrac- tive distillation using an azeotrope, such as benzene. A substitute for ethyl alcohol for solvent purposes and as a rubbing alcohol is isopropyl alcohol, or isopropanol, a colorless liquid of composition (CH 3 ) 2 CHOH, boiling point 180°F (82°C), and produced by the hydration of propylene from cracked gases. It is also used as a stabilizer in soluble oils and in drying baths for electroplating. Petrohol is isopropyl alcohol. Trichloroethanol, CCl 3 и CH 2 OH, is a viscous liquid with an ether odor, boiling at 302°F (150°C) and freez- ing at 55°F (13°C), slightly soluble in water, used for making plasti- cizers and other chemicals. The spent grain from alcohol distilleries, called stillage, is dried and marketed as livestock feed and is a better feed than the original grain because of the high concentration of pro- teins and vitamins, with the starch removed. The leaf alcohol which occurs in fruits and many plants is a hexene alcohol. It is made syn- thetically for blending in synthetic flavors and for restoring full flavor and fragrance to fruit extracts. ETHYL SILICATE. A colorless liquid of composition (CH 2 H 5 ) 4 SiO 4 , used as a source of colloidal silica in heat-resistant and acid-resistant coat- ings and for moldings. The specific gravity is 0.920 to 0.950. It is a silicic acid ester, with a normal content of 25% available silica, although tetraethyl orthosilicate has 27.9% available silica, and ethyl silicate 40 of Union Carbide has 40% silica. The latter is a brown liquid. Water hydrolyzes ethyl silicate to alcohol and silicic acid, H 4 SiO 2 , which dehydrates to an adhesive amorphous silica. For moldings, the ester is mixed with silica powder, and for such products as bearings, wood flour may be incorporated to absorb and retain the lubricating oil. Ethyl silicate solutions are employed for the surface hardening of sand molds and graphite molds for special casting. Silicic acid ester paints are used to harden and preserve stone, cement, or plaster, and for coating insulating brick. They are resis- tant to heat and to chemical fumes. Kieselsol, a German material for clarifying wine and fruit juices by precipitation of the albumin, is a 15% water solution of silicic acid. ETHYLENE. Also called ethene. A colorless, inflammable gas, CH 2 :CH 2 , produced in the cracking of petroleum. Ethylene liquefies at Ϫ154.8°F (Ϫ68.2°C). It was first produced in Holland by dehydrating ETHYLENE 359 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 [...]... worked with ordinary tools Particleboards, made with wood particles, have lower density, about 40 lb/ft3 (64 1 kg/m3), and have greater flexibility but lower strength than hardboard The process is not limited to the making of boards Wood particles are also used for low-cost molded parts, with up to 90% wood particles and the balance urea, phenolic, or melamine resin Birch or maple particles are preferred... is also marketed in bulk The melting point varies from 2 165 to 2714°F (1185 to 1490°C), but the preferred range is 2282 to 2 462 °F (1250 to 1350°C) Mohs hardness is 6 to 6. 5, and the index of refraction is 1.518 to 1.588, the lowest being orthoclase and the highest anorthite The specific gravity is 2.44 to 2 .62 for orthoclase and microline and 2 .6 to 2.8 for anorthite Tennessee and North Carolina feldspar... Trinitroanisol, used in Japanese Baka planes, has composition C6H2OCH3(NO2)3 It is about equal to TNT in power and has the advantage that it does not attack metals Tetryl, or pyronite, (NO2)3C6H2N(NO2)CH3, is a nitro derivative of benzene It is a yellow crystalline powder that melts at 266 °F (130°C) and explodes when heated to 367 °F (1 86 C) It is more sensitive to shock than TNA and has a higher rate... water-soluble impurity The red oxide has a spheroidal particle shape, while the crimson has an acicular, or needle-shaped, particle Mapico lemon yellow contains 87% Fe2O3, with 11.85% ignition loss The particles are acicular and are only half the size of the crimson particles, being only 3.9 to 31.5 in (0.1 to 0.8 m) Mapico brown contains 93.1% Fe2O3 and 5 FeO Its particles are cubic and of sizes from 7.9 to... Carbide, contains 66 to 70% chromium in grades of 4.5, 5, 6, and 7% carbon It is used for making tool steels, ball-bearing steels, and other alloy steels It melts at about 2280°F (1250°C) It is marketed as crushed alloy in sizes up to 2 in (5 cm) and as lump alloy in lumps up to about 75 lb (34 kg) Low-carbon ferrochrome of this company contains 67 to 72% chromium, in grades of 0. 06, 0.10, 0.15, 0.20,... material of feldspars and other minerals, containing 60 % silica, 24 alumina, 6 calcia, 6 sodium oxide, and 3 potassium oxide Another feldspar material is alaskite, a feldspar and quartz mixture from North Carolina It is classified as a pegmatitic granite Ground feldspar for enamels is sometimes called glass spar Dental spar is specially selected potash feldspar used in making artificial teeth FELT... website Materials, Their Properties and Uses 3 76 FERRIC OXIDE chemical and physical properties of this fiber, it is called dragon fur in the felting industry It also has a low friction coefficient and is repellent to sticky materials, giving high filtering efficiency and easy cleaning The Scottfelt, of Scott Paper Co., is a foam filter made from urethane foam compressed under heat and pressure to 0. 067 ... ferrochrome, for making cast irons, contains 62 to 66 % chromium and 5 carbon Another has about 40% chromium, 18 silicon, and 9 manganese It is used for ladle additions to cast iron to give uniform structure and increase the strength and hardness Addition of 1% of the alloy to a cast iron of 3.40% total carbon, with resultant balance of 1.30% silicon, 0 .60 manganese, and 0.35 chromium, gives a dense... it is added to the steel It was used for making irons and steels by the Bessemer process Grade A spiegeleisen has 19 to 21% manganese and 1 silicon; Grade B has 26 to 28% manganese and 1 silicon The melting point is from 1950 to 2 265 °F (1 066 to 1240°C) An iron containing a high percentage of phosphorus, used for adding phosphorus to steels Small amounts of phosphorus are used in open-hearth steels to... FERTILIZERS Materials added to the soil to supply plant food either directly or by chemical reaction with the soil The preparation of fertilizers is now one of the major industries, and commercial fertilizers include nitrates, phosphates, potash salts, calcium salts, and mixtures They may also include the materials which regulate the acidity of the soil for better plant production, such as lime, and the materials . derivative of benzene. It is a yellow crystalline powder that melts at 266 °F (130°C) and explodes when heated to 367 °F (1 86 C). It is more sensitive to shock than TNA and has a higher rate of detonation. gravity is 1. 562 or, as a liq- uid compressed in cylinders, 0.724. It is used for fuel, as a welding gas, as a refrigerant, and for vapor-pressure thermometers. Hexyl ether, C 6 H 13 OC 6 H 13 , has. as given at the website. Materials, Their Properties and Uses ESTERS. Combinations of alcohols with organic acids, which form sev- eral important groups of commercial materials. The esters occur