Abstract
Chromium-Carbide layers were deposited on diamond particles by disproportionation reaction in molten salt. In order to clarify the effect of the chromium-carbide layers on diamond particles for thermal property of the coated diamond particles, the specimens were tested by thermogravimetry at high temperature (700°-800°), scanning electron microscopy of the surface and X-ray diffractometry. In addition, the change of the specimens surface at high temperature in air atmosphere and reducing atmosphere was observed by high temperature microscope. The results obtained were as follows.
1) Under air atmosphere, weight loss of chromium-carbide coated diamonds were within 0.1% at 700° and 750°, and 18.6% at 800° for 40min. On the other hand, weight loss for non coated diamonds was 24.7% under the last conditions.
2) Under air atmosphere, appearance of each chromium-carbide layer did not nearly change, but heat treatment at 800° worsened the surface of internal diamond particles.
3) Chromium-carbide layers on the surface of specimen were Cr3C2 and Cr7C3 in initial condition, but thin Cr2O3 phase was formed by heat treatment under air atmosphere.
4) The change of appearance of chromium-carbide layers did not occur through the observation under high temperature microscope.
