Atmospheric Pressure Plasma Treatment of Magnesium Alloy for Enhanced Coating Adhesion and Corrosion Resistance

Atmospheric pressure plasma (AP) treatment, using an open-air jet of ionized CO2, N2, or air, was applied to AZ91D Mg alloy surfaces investigate its effects on primer coating adhesion and corrosion resistance. The CO2 air AP treatments formed O- C-rich surface layer (Mg-O-C) consisting agglomerated nanoparticles pits with a depth few microns increasing the roughness by 6–8 times compared reference 600 grit-finished surface. Then, three commercial primers, zinc phosphate (ZnP), chromate-containing epoxy, MIL23377, were treated evaluate resistance associated adhesion. Microscopic analysis demonstrated stronger interlocking between nano-/microrough Mg-O-C untreated (600 grit-finished) surfaces, indicating improved Crosscut tests MIL23377 AP-treated showed highest level adhesion, ASTM class 5B. Salt spray that after 8 days exposure, coatings had areas more than four smaller N2 treatment similar enhancement. preliminary operation expenses for estimated at USD 30.62, 35.45, 29.75 (from cylinder)/USD 0.66 compressor) per m2, respectively.