Alloys of chromium

Aluminium-niobium alloys are best produced by the Goldschmidt process. A product which contains about 8 per cent, of aluminium is harder than glass or quartz its density is 7 5.3 A brittle alloy of chromium and niobium is obtained by fusing green chromium oxide and niobium together in the electric furnace.1... 

Disc and nozzle High corrosion-resistant alloy of chromium-nickel or nickel-chromium Ferritic steels not acceptable... 

Flint GN, Carter SV, Fairman B. 1998. Skin allergy from exposure to alloys of chromium. Contact Dermatitis 39 315-316. 

Ferrochrome, a high-chromium alloy with iron, is made by reducing chromite with carbon in the electric furnace. It is used for making alloy steels. The alloys of chromium are very important, especially the alloy steels. The chromium steels are very hard, tough, and. strong. They are used for armor plate, projectiles, safes, etc. Ordinary stainless steel contains 14 to 18% chromium, and usually 8% nickel. 

Alloys of chromium and silicon are readily obtained by heating chromium sesquioxide with excess of silicon at 11 white heat, or with silicon carbide, or silicon carbide and carbon, in the electric furnace or by strongly heating chromium sesquioxide, silica, and aluminium. From these alloys several definite silicides have been isolated, which are usually grey in colour, hard and brittle, and very resistant to acids, except hydrofluoric acid, which readily, decomposes them. The silicides, CrjSi, CrjSi, CrgSia, and CrSij, have been obtained in a state of comparative purity by special methods of preparation. ... 

For general work at higher temperatures, several different types of couples are employed in this country. Up to 360°C. for extreme precision or to 500°C. for a precision of 5 to 10°C. the couple may consist of one wire of copper and the other wire of constantan. Iron-constantan or nichrome-constantan may be employed for technical processes below 900°C. For operation below 1,100°C. special patented alloys of chromium and nickel and of aluminum and nickel, chromel-alumek or nichrome-alumel are very satisfactory even for continuous service. For the temperature range 300 to 1,500°C. the Le Chatelier couple should be employed. This couple consists of one wire of platinum and the other wire an alloy containing 90 per cent platinum and 10 per cent rhodium. Other alloys and metals may be employed for special work but the above combinations are sufficient for almost all technical processes carried on in the temperature range 0 to 1,500°C. No satisfactory couple has been developed for operation much above 1,500°C. 

Borcher s metal. A group of alloys of chromium with nickel and cobalt or of chromium and iron with a small proportion of molybdenum and/or silver or gold. Heat and corrosion resistant. 

Amongst the non-ferrous alloys of chromium, nichrome, cochrome, stellite and magnet steels (p. 245) may be mentioned. 

Elinvar /el-in-var/ (Trademark) An alloy of chromium, iron, and nickel. It is used for making hairsprings for clocks and watches because its elasticity does not vary with temperature. 

R. A. Perkins, Alloying of chromium to resist nitridation, NASA Report NASA-Cr-72892, July, 1971. 

Nickel is also rather rare. The common U.S. coin called the nickel is mostly composed of copper. It is an alloy that is about 25% nickel. An alloy of chromium and nickel, called nichrome, is a nickel-chromium alloy and is used to make heating elements and wires. Nickel is also used in nickel-cadmium (Ni-Cad) batteries, rechargeable batteries that have been used in laptop computers and other devices. Nickel compounds also display colors, typically green. 

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