Corrosion resistance of amorphous hydrogenated SiC and diamond-like coatings deposited by r.f. plasma-enhanced chemical vapour deposition

The properties and corrosion resistance of amorphous hydrogenated carbon and amorphous hydrogenated SiC films deposited by r.f.-plasma-enhanced chemical vapor deposition at low temperatures ( < 200 deg C) are described. SiC coatings were prepared from SiH sub 4 -CH sub 4 gas mixtures. Hydrogenated diamond-like coatings were deposited from classical CH sub 4 -H sub 2 mixtures. The effect of various deposition parameters was investigated. Microstructural and mechanical properties of the films were studied (density, hydrogen content, nanohardness, internal stress, critical load and friction coefficient). Two examples of corrosion resistance are given: (1) the corrosion resistance and biocompatibility of SiC and diamond-like coatings deposited on metal implants (Ti alloy) (the corrosion resistance is evaluated through potentiodynamic polarization tests in biological media; the biocompatibility of coated and uncoated metals is compared using differentiated human cell curves); and (2) the corrosion resistance of SiC-coated magnesium in chloride-containing boric borate buffer at pH=9.3 evaluated from anodic polarization curves and scanning electron microscopy studies.