Investigation of a novel self-sealing pore micro-arc oxidation film on AM60 magnesium alloy

Abstract

Micro-arc oxidation (MAO) is one of the promising methods to improve the corrosion resistance of magnesium alloys. However, there are plenty of micro-pores in the traditional MAO films, deteriorating their protection property. A novel self-sealing pore MAO film was developed in this paper. The morphologies and chemical composition of the film were detected by scanning electron microscopy (SEM) and energy dispersive X–ray spectroscopy (EDX). The corrosion behavior was investigated by electrochemical and salt spray tests. The possible film formation and corrosion mechanisms were proposed. The self-sealing pore film presents a blue appearance. Most of the micro-pores in the surface of the film are sealed during the film formation process. The chemical composition of the film mainly contains Mg, O, Ti, F and P. The self-sealing pore film exhibits better corrosion resistance compared with the traditional silicate film. Especially, the self-sealing pore film keeps intact after salt spray test for 2000 h, which can be attributed to its high compactness.