The vaporization behavior of zirconium carbide was studied in the tempera¬ture range 2620 to 2747 °K by means of the Knudsen and Langmuir techniques in order to investigate the nature of the vaporization process and to determine the high temperature stability of the compound. At 2675°K, the standard free energy of formation was found to be -38.9 (±1.5) kilocalories. Agreement of the results of the two methods leads to the conclusions that accommodation coefficients must have been near unity and that molecular carbide species were not of major im¬portance. Free energy functions were also estimated and used to derive a heat of formation, △H°298 = -47.7 ± 5.0 kilocalories.
展开▼
