Effect of Different Atmospheric Plasma Treatment on Corrosion Behavior of AZ91D Cast Mg Alloy

Vehicle lightweighting, including use of magnesium (Mg) alloys as structural components within an autobody, can improve the overall energy efficiency and increase the range of electric vehicles. However, Mg alloys joined with dissimilar metals can suffer from galvanic corrosion, which is a major technical challenge. To mitigate galvanic corrosion, an electrically-insulating layer on the joining surfaces, grown from the Mg alloy surface, has been proposed. To achieve such an insulating surface, atmospheric plasma (AP) treatment was performed on a AZ91D Mg alloy. The aim of AP treatment is to form an insulating layer that can provide corrosion protection for the underlaying AZ91D. Currently, AP treatments of AZ91D coupons are underway with varying process parameters (e.g. power, nozzle height, overlap). The AP-treated AZ91D samples were characterized to investigate the elemental composition and microstructural evolution of the processed surfaces and sub-surface regions. Results of electrochemical corrosion evaluation of AP-treated AZ91D will be reported.