Synergistic Effect of Polyurethane on Pore-Sealing and Lubrication of Microarc Oxidation Coating.

Microarc oxidation (MAO) is a widely used surface treatment technology. However, its processing inevitably leads to the presence of micropores, microcracks, and other defects in the MAO coating. These defects lead to suboptimal tribological performance and diminished corrosion resistance of the MAO coating. Thus, this study proposed a new pore-sealing method with environmental protection and high efficiency. Polyurethane reactive (PUR) composite coating was prepared on the surface of MAO coating. The sealing effect of the PUR sample was analyzed using scanning electron microscopy (SEM). The molecular structure and elemental changes of the coating were analyzed using X-ray photoelectron spectroscopy (XPS). The tribological properties were analyzed using a tribological testing machine, and the corrosion resistance was tested using an electrochemical workstation. The test results show that the lubricity and corrosion resistance of PUR sample are improved significantly compared with MAO coating. When the mass fraction of PUR is 3 wt %, the PUR sample shows the best lubrication performance, and the coefficient of friction decreases by 70.8%. Compared with the traditional sealing technology, this experimental method is simple and low-cost and has a wide application prospect, which promotes the development of MAO technology.