THE CVD OF CHROMIUM CARBIDE

Chromium carbide has three phases Cr23Cg, Cr7C3, Cr3C2 (major). The latter phase is the one reviewed here. Chromium carbideis an important material because of its excellent resistance to corrosion. It is the most oxidation resistant of all metal carbides. Its characteristics and properties are summarized in Table 9.3. 

Chemical Resistance. The chemical resistance of chromium carbide is superior to that of other interstitial carbides. Oxidation in air starts at 1000°C and a dense and strong oxide layer is formed. It is insoluble in cold HCl but dissolves in hot oxidizing acids. 

A common deposition reaction combines the metal chloride with a hydrocarbon, such as butane, at an optimum deposition temperature of 1000°C.9 1 Other hydrocarbons can also be used. Another useful reaction is the decomposition of the chromium di cumene Cr[(C6H5)C3H7]2 in atemperature range of 300-550°C and at pressures of 0.5-50 Torr.0 1 

Special coating for maximum chemical resistance. Intermediate layer for tool steel coatings. 

Crystal Structure and Lattice Parameters (nm) Orthorhombic, a = 0.283, b = 0.554, c = 1.1470 Cr3C2 is an intermediate carbide having carbon chains with C-C distance approximately 0.165 nm running through distorted metal lattice where the Cr atoms are at the corners of trigonal prisms and the carbon atoms in the center of the prisms.i li  

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