Accession Number : AD0780111

Title :   Thermodynamic Properties of High Temperature Materials.

Descriptive Note : Final rept.,


Personal Author(s) : Potter,Norman D. ; Piper,Gerry

Report Date : 31 MAR 1974

Pagination or Media Count : 32

Abstract : A careful equilibrium study of the Si-N vapor system of mass spectrometry has shown that the only important binary Si-N vapor species is the previously known Si2N. Its heat of formation is 83 plus or minus 4 Kcal/mole. No ternary Si-N-O nor Si-C-N species were found. The accepted heats of formation of Si2C(g) and SiC2(g) were confirmed as was the heat of formation of Si3(g). The vaporization behavior of Si3N4(c) was studied and found to be quite complex. From a study of the vaporization of VF3 it was found that the primary vapor species at VF3(g) with minor, and approximately equal partial pressures of VF2(g) and VF4(g). Due to sample impurity little could be inferred from the vaporization of VF4. From these experiments and estimates of the auxiliary heats and thermal function, heats of formation were estimated. (Modified author abstract)

Descriptors :   *Vaporization, *Silicon nitrides, Chemical equilibrium, Heat of formation, Gases

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE