Effect of acetylene content in working gas on microstructure and thermal stability of DLC coating

Abstract

The DLC coatings were deposited onto the surface of 304 stainless steel by using PE-CVD method and Ar+C2H2 as working gas. The effects of the methane content in the working gas on the structure, hardness, thermal stability of the coating were analyzed by means of SEM, FTIR, Raman and nano-indenter. It is found that controlling methane content in the work gas can be used as an effective means to modulate the structure and performance of the DLC coating. With reducing methane content in the gas mixture, the surface sputtering effect by Ar+ is enhanced, which leads a drop of hydrogen content in the coating. A high sp3C-C content in the DLC coating can be obtained by selecting an appropriate methane flow, which derives a combination of high hardness and good thermal stability for the coating. a combination of high hardness and good thermal stability for the coating.