Superhard nanocrystalline silicon carbide films

Abstract

Nanocrystalline silicon carbide films were deposited by thermal plasma chemical vapor deposition, with film growth rates on the order of 10μm∕min. Films were deposited on molybdenum substrates, with substrate temperature ranging from 750-1250 °C. The films are composed primarily of β-SiC nanocrystallites. Film mechanical properties were investigated by nanoindentation. As substrate temperature increased the average grain size, the crystalline fraction in the film, and the hardness all increased. For substrate temperatures above 1200 °C the average grain size equaled 10-20 nm, the crystalline fraction equaled 80-85 %, and the film hardness equaled approximately 50 GPa.