INFLUENCE OF Na 2SiF6 ON THE SURFACE MORPHOLOGY AND CORROSION RESISTANCE OF AN AM60 MAGNESIUM ALLOY COATED BY MICRO ARC OXIDATION

Abstract

Oxide coatings were formed by micro arc oxidation (MAO) on an AM60 magnesium alloy substrate. The effects of Na2SiF6 in an electrolytic solution on the micro arc oxidation process and the structure and mechanical properties of the oxide coatings were investigated. The results showed that the MAO coating produced in the electrolyte with Na2SiF6 was thicker and more uniform than that produced in the electrolyte without Na2SiF6. The pore diameter of the MAO coatings was reduced by the addition of Na2SiF6, while the coating density and surface roughness were increased. The coating formed in the electrolytic solution with or without the Na2SiF6 had a higher surface hardness than the AM60 alloy and the results of the corrosion behavior for including Na2SiF6 showed better resistance than that formed in the solution without Na2SiF6.