Metal dusting, carburization and diamond deposition on Fe-Cr alloys in CH4-H2 plasma atmospheres

Fe-Cr model alloys (with 20-80 wt.% Cr) were exposed to a CH4-H2 mixture in a microwave plasma enhanced chemical vapor deposition (CVD) atmosphere. Severe metal dusting and carburization are observed on the low-Cr alloys, meanwhile, diamond cannot nucleate until a graphite intermediate layer has formed on the substrate, which takes a long incubation time. Increasing Cr concentrations in the Fe-Cr alloys promotes the formation of a Cr carbide buffer layer, which inhibits metal dusting and the formation of graphite interlayer. Consequently, diamond nucleation and growth are greatly enhanced, and continuous diamond films with enhanced adhesion are deposited on the Fe-80Cr alloys.