Enhanced properties of microarc oxide coating by secondary treatment of laser surface remelting

As an efficient surface treatment method, microarc oxidation (MAO) solves the problems of severe pollution and high cost of traditional methods such as electroplating and anodic oxidation. The prepared coatings are characterized by high bonding, wear resistance, and corrosion resistance. However, the presence of porous and cracked defects on the coating still has a negative impact on the performance of the coating. In this study, the laser surface remelting technique is proposed for the secondary treatment of the MAO coatings to cover the porous structure of the coating surface by the melt and to exclude the pores in order to further improve the coating performance. In order to better characterize the coatings, the microscopic morphological features, phase composition changes, elemental composition, and distribution of the coatings before and after the laser surface remelting treatment were analyzed by scanning electron microscopy, x-ray diffraction mapping, and energy dispersive spectroscopy. Finally, the coating properties were characterized by friction and electrochemical experiments, and the results showed that laser surface remelting secondary treatment on MAO coating can effectively improve the wear resistance and corrosion resistance of the coating and significantly reduce the friction coefficient. The reasons for the improvement of the coating properties by laser surface remelting are also explained in detail.