SYNTHESIS OF DIAMOND FILMS ON MOLYBDENUM SUBSTRATE SURFACE BY COMBUSTION FLAME

Abstract

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo 2 C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.