THE CVD OF HAFNIUM CARBIDE

Hafnium carbide (HfC) is an interstitial carbide which, with tantalum carbide, is the most refractory compound known. Its characteristics and properties are summarized in Table 9.4. 

Chemical Resistance. Hafnium carbide oxidizes in air at 500°C. It is not as chemically resistant as TiC and is similar to ZrC in that respect. 

Isomorphism. Like TiC and ZrC, HfC forms solid solutions with oxygen and nitrogen, which have a wide range of composition. HfC forms solid solutions with the other monocarbides of Group IV and V, particularly NbC.b l 

HfC is produced by CVD mostly on an experimental basis. The most common deposition system is the reaction of the metal chloride with a hydrocarbon, which can be propane (C3H8), propene (C3H6), toluene (C7Hg), or methane (CH4) as follows b H l 

The chloride is usually generated in situ. This reaction occurs over a wide range of temperature (900-1500°C) and pressure from 10 Torrto atmospheric. Whisker formation has been observed at 1 atm and 1230°C. 

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