Anodic oxidation and sol–gel coatings for corrosion and wear protection of AM60B alloy

Abstract

In this paper a study on the corrosion and wear protection of AM60B magnesium alloy, by means of multilayer coating, is described. The coating mainly consists of a porous oxide layer MgO, produced by oxidation in microarc regime, and a single or multilayer top coat of SiOx produced by sol–gel technique and deposited by either a dip or spray coating method. The anodic oxidation pretreatment improves the adhesion of the sol–gel layers, which seal the porosity of MgO and improve corrosion protection. Furthermore, the multilayer coating significantly improves AM60B wear resistance. Scanning electron microscopy and radiofrequency glow discharge optical emission spectroscopy were used to assess surface morphologies and in depth elemental profiles of the coatings. Electrochemical polarisation tests and wear tests were performed to evaluate the corrosion resistance behaviour and the wear resistance of the coated magnesium alloys.