Enhanced corrosion resistance of Mg and Mg alloys with fs-laser printed hydrophobic and periodically microrippled surface for armor application

Magnesium (Mg) and its alloys have properties such as high strength-to-weight ratio and good castability, which make them quite promising in industrial applications. Future widespread application of them needs to overcome the limitations such as the fast corrosion rate of Mg and Mg alloys. In this study, an anticorrosion armor with was printed using femtosecond (fs) laser direct writing method. This protective armor is covered with controllable micro-nano structures. Thus, it has a controllable water contact angle ranged from 68° to 158°. In addition, due to the fs laser energy deposition, a grain refined layer less than 15 μm consisting of nanocrystals forms on the surface. Under the synergistic effects of the superhydrophobic surface and nanocrystal layer, Mg and Mg alloys (AZ91D) exhibit significantly enhanced corrosion voltage and exponentially decreased corrosion current density. In particular, pitting on the surface is largely improved, and the corrosion pits on the surface after laser-treatment are approximately 200 times smaller in depth (<2.5 μm) than those of the pristine surface (531 μm). Therefore, the armor on Mg and Mg alloys with enhanced corrosion resistance can be successfully fabricated by the fs-laser direct printing method, extensively used in Mg and Mg alloys applications.