THE CVD OF NIOBIUM CARBIDE

Niobium carbide, also known as columbium carbide, is a important refractory material with a high melting point. It is used as a CVD coating mostly on an experimental basis. Niobium carbide has two phases Nb2C and the monocarbide NbC. The latter is the only phase of industrial importance and the only one reviewed here. Its characteristics and properties are summarized in Table 9.5. 

Chemical Resistance. NbC oxidizes in air at 800°C. It reacts with nitrogen and ammonia at a high temperature to form NbN. It is less chemically resistantthan TaC. Itis dissolved by hot oxidizing acids. 

Color gray sometimes with a lavender tint 

Heat of Formation (-AHf) at 298K (kJ/g-atom metal) 140.6 Thermal Conductivity 14.2(W/m °C) 

Electrical Resistivity 35 pGcm Superconductive Transition Temperature 6K Hall Constant -1.3 x 10 cmVA s Magnetic Susceptibility +15.3 x 10 emu/mol 

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