Pressure effect on bonding of advanced carbon-based coatings under high temperature

Abstract

The aim of this paper was to systemically study the pressure influence of the bonding of four types of DLC coatings during annealing in high temperatures (HT) and high pressures (HP). The results show that in the two silicon free coatings, Cr2C3 crystal are found to be generated during the argon annealing, but no obvious phase transformation was observed in the two silicon containing coatings when annealed at the same temperature, the sp3 content of HIPped samples is to some extent higher than that of argon annealed samples. The influence of high pressure is more significant on the hydrogenated DLC than on the hydrogen free DLC. Si dopant can inhibit the formation of chromium carbides during the argon and HIP annealing treatment. The hydrogen-free DLC coatings are more stable than the hydrogenated DLC coatings; silicon containing DLC coatings possess a better stability than silicon free DLC coatings. The high pressure can delay the carbon bonding change from sp3 to sp2 or graphitisation. Based on sp3 content, DCr coating (hydrogenated and silicon free coating) was the most unstable coating under both high temperature and high pressure condition, while GCrSi coating (hydrogen-free and silicon containing coating) was the most stable coating.