Effect of Nitrogen Addition Flow Rate on Bonding Strength of Diamond Films Synthesized by Flame Combustion Using High-Purity Acetylene Gas

Abstract

Diamond films have been synthesized by flame combustion using a mixture of high-purity acetylene and oxygen gas. To obtain good quality diamond films and to achieve good adhesion, diamond films were synthesized by stable flame combustion using the mixture of high-purity acetylene and oxygen gas with nitrogen gas added as the diamond promotion agent; nitrogen flow rate was carefully varied. In previous study, the optimal nitrogen flow rate was 0.500 cm 3 /s, and good quality diamond films were synthesized. In this study, to investigate effects of nitrogen addition flow rate on the bonding strength of synthesized films, the scratch test by indenter of Rockwell to synthesized delamination-free diamond films was performed, and the bonding strength was discussed. In results, the bonding strength was increased with increasing the nitrogen flow rate from the nitrogen flow rate 0.000 cm 3 /s, and it was concluded that diamond films synthesized by nitrogen flow rate 0.500 cm 3 /s had the highest bonding strength. And, the bonding strength was decreased with increasing the nitrogen flow rate from the nitrogen flow rate 0.500 cm 3 /s. The bonding strength of synthesized diamond films was changed by varying the nitrogen flow rate. Thus, nitrogen addition to high-purity acetylene affects bonding strength. The reason for this is that the nitrogen affects the crystallite morphology of synthesized diamond films. The nitrogen flow rate 0.500 cm 3 /s is good condition for the bonding strength.