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 amorp hous hydrogenated carbon and amorphous hydrogenated SiC films deposite d by r.f.-plasma-enhanced chemical vapour deposition at low temperatur es (below 200-degrees-C). SiC coatings were prepared from SiH4-CH4 gas mixtures. Hydrogenated diamond-like coatings were deposited from clas sical CH4-H-2 mixtures. The influence of various deposition parameters was investigated. Microstructural and mechanical properties of the fi lms were studied (density, hydrogen content, nanohardness, internal st ress, critical load and friction coefficient). Two examples of corrosi on resistance are given: (1) the corrosion resistance and biocompatibi lity 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 cultu res); and (2) the corrosion resistance of SiC-coated magnesium in chlo ride-containing boric borate buffer at pH = 9.3 evaluated from anodic polarization curves and scanning electron Microscopy studies.