Open-Air Plasma Assisted Si–O–C Layer Deposition on AZ91D Mg Alloy for Corrosion Mitigation

Use of Mg alloyMagnesium alloy structural parts can enable lightweight automobiles for improved energy efficiency. High corrosionCorrosion susceptibility of Mg alloysMagnesium alloy, however, remains as a technical challenge against their application in vehicle-structures. This work investigates open-air plasma assisted Si–O–C coating as a corrosionCorrosion barrier for AZ91D Mg alloyMagnesium alloy. The open-air plasma coating does not involve wet chemical process and is amenable to the industries experienced in other plasma-based processes. As-deposited coatings on AZ91D substrates were characterized by advanced microscopic characterizationCharacterization techniques, including SEM, STEM, and EDS. CorrosionCorrosion evaluation was performed using electrochemical impedance spectroscopy, polarization, and H2 collection measurements in 3.5 wt.% NaCl solution. Post-immersion AZ91D samples, that were uncoated or Si–O–C coated condition, were also characterized by SEM, STEM, and EDS. The results indicate that plasma assisted Si–O–C coating delayed the initiation of corrosionCorrosion and the progression of corrosionCorrosion attack.