AN EXPERIMENTAL APPROACH TO THE ANALYSIS OF THE ADHESION PROPERTIES OF SIC COATINGS DEPOSITED ON STEEL SUBSTRATES

SiC coatings were deposited by a plasma-assisted chemical vapour deposition technique (r.f. coupled) on steel substrates from Si(CH3)4-Ar mixtures. Different atomic compositions (Si:C ratios) were obtained vs. deposition parameters, and the adhesive properties were semiquantitatively established. By three-point bending tests, different steps in the damage evolution were observed and were discussed; they are related to the deposition pressure and the ion cleaning of the substrate. From the occurrence of adhesion loss and the corresponding critical strain at the interface, apparent adhesion parameters were calculated through an analytical formulation. The results tend to indicate that the layers obtained are strongly adherent.