Development of Cerium-based Conversion Coating on AZ31 Magnesium Alloy

Abstract

Abstract The use of chromate baths is being progressively restricted owing to the high toxicity of the hexavalent chromium (Cr6+) compounds. In this work, chemical conversion coating on AZ31 (3% Al, 1% Zn) magnesium alloy was performed by immersion in 5 mM Ce(NO3)3 solution with and without addition of Al(NO3)3 and Ca(OH)2. It was noted that addition of Al(NO3)3 and Ca(OH)2 to the cerium-based solution enhanced the surface properties and the corrosion resistance from anodic polarization in a 0.017 mol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K.