Carbide, aluminum beryllium

Beryllium oxide Zirconium oxide Aluminum nitride Boron carbide Silicon carbide and nitride Tungsten carbide Beryllium carbide... 

Whiskers (nonoxides) (aluminum nitride, boron carbide, silicon carbide, silicon nitride, tungsten carbide, beryllium carbide)... 

The saltlike carbides formed from beryllium (Be2C) and from aluminum (AI4C3) are best described as methides they yield methane upon hydrolysis, and the carbon atoms have been found to be far enough apart from each other to preclude any type of carbon-carbon binding. One of the two carbides of magnesium has the composition Mg2C3 and yields methylacetylene, CH3C=CH, upon hydrolysis the carbide anion here is presumably [-3C—C=C <-> 20=C=C-2]. 

Carbides Steel, nitriding Steel, carburizing Steel, water-hardening Steel, oil-hardening Steel, air-hardening Nickel, cobalt alloy Steel, prehardened 44 Rc Beryllium, copper Steel, prehardened 28 Rc Aluminum bronze Steel, low alloy 6t carbon Kirksite (zinc alloy) Aluminum, alloy Brass... 

On the other hand, the number of highly reactive chemicals that advance from the sta of laboratory curiosities to commercial items is constantly increasing, Some of these are sodium hydride (NaH), lithium aluminum hydride (LiAlH ), lithium borohydride (LiBH ), aluminum and beryllium borohydride, Al(BH4)3 and BefBH ), the sodium salt of nitromethane sodium methane nitronate or if one prefers sodium nitro methanate (HjCNOgNa), - and barium carbide (BaCg)/ all of which can flame on contact with water. Again, it must be stressed that particle size and other conditions of exposure may determine whether there is flaming or merely a violent reaction on exposure to water, air, or both. 

These compounds have the characteristics of a salt, that is, they have a fixed composition their physical properties are unlike ftiose of their constituent elements they are generally transparent to optical radiation and are good electrical insulators. They form transparent and colorless crystals. Some contain ions such as aluminum carbide (AI4C3) and beryllium carbide (Be2C). They evolve methane when hydrolyzed and for that reason are usually known as methanides. Others contain ions such as calcium carbide (CaC2) they yield acetylene when hydrolyzed and are known as acetylides.1 1... 

Although some of these salt-like carbides have high melting point (for instance beryllium carbide sublimes above 2100°C), they are decomposed readily by water and/or dilute acids at ordinary temperatures and thus do not meet the refractory criteria of this book. However, this does not necessarily detract from their usefulness. Aluminum and beryllium carbides, the three actinide carbides ThC, UC and PuC, and several lanthanide (rare earth) carbides are important industrial materials in several areas such as atomic energy and others. 

As can be seen in Table 4.2, the thermal conductivities of the Group rv carbides, nitrides, and borides are relatively close. They are also similar to those of the host metals and, from this standpoint, reflect the metallic character of these compounds. However, their conductivities are much lower than that of the best conductors such as Type II diamond (2000 W/m-K), silver (420 W/m-K), copper (385 W/m K), beryllium oxide (260 W/m-K), and aluminum nitride (220 W/m-K). 

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