Solid zirconium carbide, ZrC cr

Zirconium carbide is a hard, high melting compound. Carbon forms a solid solution with either a- or (3-Zr whereby a small fraction of interstitial sites are filled with carbon atoms [95FER]. At much higher contents of carbon, in non stoichiometrical ZrC where a considerable amount of the interstitial sites are filled, the compound is considered to be derived from a face centred cubic, metastable form of zirconium [95FER]. 

The enthalpy of formation of ZrC. has been determined from the measured heat of combustion associated with Reaction (V.77)  

This reaction was studied in detail by Baker et al. [69BAK/STO] using a range of Zr C stoichiometries (0.63 X 0.98). The results found for the enthalpy of formation of ZrC are listed in Table V-35. 

From this equation, they determined an enthalpy of formation for ZrC(cr) of  

The selected value is in good agreement with the value selected by [85CHA/DAV] (37.90 J-K -mor ). 

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