Fabrication and evaluation of protective SiOx layers using plasma-enhanced chemical vapor deposition

SiOx layers were fabricated on the surface of magnesium alloy using plasma-enhanced chemical vapor deposition (PECVD) to improve their surface properties as transparent and protective layers. The SiOx layers were deposited with various thicknesses and substrate temperatures to evaluate the effects of substrate temperature with respect to film thicknesses. Cross-sectional images revealed that thin films grew at the interface of the SiOx layers and magnesium substrates during PECVD. The elemental composition analysis demonstrated that the films were composed of a mixture of Mg, Si, and O components. Hardness measurements were performed to compare the mechanical properties of layers deposited at substrate temperatures of 50 and 300 °C. Salt spray tests confirmed that the SiOx layers deposited at higher temperatures played significant roles as protective layers. The results demonstrated that the substrate temperature during PECVD played an important role in the fabrication of protective SiOx layers on the surfaces of magnesium substrates.