Micro-arc oxide Film of Aluminum Coating Pre-sprayed on AZ31 Magnesium Alloy

摘要

Using the micro-arc oxidation(MAO)in silicate electrolyte,ceramic film was formed on pure Al coating previously sprayedon AZ31 magnesium alloy. The surface and cross-sectionalmorphologies, distribution of elements, phase composition,microhardness, bonding strength and corrosion resistance of thefilm were systematically investigated. The results show that theMAO film is uniform and compact, mainly comprised ofα-Al_2O_3,γ-Al_2O_3 and 3Al_2O_3·2SiO_2. The ceramic film adhereswell to the Al coating with the average hardness of 1197 HV.The results of polarization curves in 3.5wt.% NaCl solutionshow that the present technology can obviously improve thecorrosion resistance of AZ31 magnesium alloy.