CORROSION-RESISTANCE OF AMORPHOUS HYDROGENATED SIC AND DIAMOND-LIKE COATINGS DEPOSITED BY RF-PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

This paper reports on the properties and corrosion resistance of amorphous hydrogenated carbon and amorphous hydrogenated SiC films deposited by r.f.-plasma-enhanced chemical vapour deposition at low temperatures (below 200-degrees-C). SiC coatings were prepared from SiH4-CH4 gas mixtures. Hydrogenated diamond-like coatings were deposited from classical CH4-H-2 mixtures. The influence 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 cultures); 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.