Characterization of interfacial layers grown between magnesium substrates and SiOx films deposited by plasma-enhanced CVD

SiOx films were deposited on the surface of AZ31 magnesium alloy by plasma-enhanced chemical vapor deposition (PECVD) in order to investigate the film properties and to characterize the formed interfacial layers. Surface and cross-sectional images showed that the SiOx films were fabricated without any apparent cracks or pores on the substrate surface. Analysis results of the cross-sectional structures revealed that interfacial layers grew gradually between the SiOx films and the magnesium substrate with an increase in deposition time. The cross-sectional compositions of the films showed that the interfacial layers were composed of Si, Mg, and O components. Detailed analysis of the compositions confirmed that the interfacial layers were composed of bi-layers or multi-layers, wherein the compositions were dependent on the depth of the interfacial layers. Adhesion tests showed that the interfacial layers had good adhesion strength, indicating that adhesion of the SiOx films was not affected by the growth of interfacial layers during PECVD.