A-SiC:H films as perspective wear-resistant coatings

Abstract

Amorphous hydrogenated silicon carbide (a-SiC:H) films have been deposited from methyltrichlorosilane (MTCS) in a 40.56 MHz PECVD reactor with an additional bias at a substrate. The substrates were crystalline silicon wafers. The as-deposited films consist of approximately 60–70 at.% Si, 20–30 at.% C, up to 8 at.% O and 0.8% Cl. The thickness of the coatings was approximately 0.2–0.4 μm. Film morphology investigations have shown that the coatings are homogeneous, and the substrate-coating zone points to the high adhesion of the coating to the substrate. From nanoindentation tests it follows that a-SiC:H coatings demonstrate the hardness up to 10 GPa and elastic modulus of 118 GPa. The samples annealed at 600 °C have higher hardness than the as-deposited films (by approx. 25%). Ball-on-plane tests have revealed that the abrasive wear resistance of the covered substrates is 1.5–4 times higher than that of the un-covered ones. So, despite the comparatively low hardness, the a-SiC:H films demonstrate good tribological properties, which make them suitable for applying as low-cost wear-resistant coatings. The possible mechanisms describing the tribological properties of a-SiC:H films are discussed.