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

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.