Preparation and characterization of Mg-P coatings on Mg-Zn-Y-Nd alloy for corrosion protection

Abstract

Abstract To improve the corrosion resistance of Mg-Zn-Y-Nd alloy, Mg-P coatings were prepared on the surface by a simple chemical conversion method. The Mg-P coatings were optimized by regulating the reaction conditions such as the pH value of the conversion solution (4.2, 5, 6, and 7), treatment temperature (20 °C, 40 °C, and 80 °C), and treatment time (1 h, 2 h, and 3 h) in this study. Scanning electron microscopy (SEM) showed that the optimized Mg-P coating has a uniform surface structure. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results demonstrated that the Mg-P coating consists of MgNH4PO4·6H2O and MgHPO4·3H2O. The cross-sectional morphology revealed that the Mg-P coating has a rough structure with a thickness of 8 μm. The effect of Mg-P coating on the corrosion resistance of Mg-Zn-Y-Nd alloy was investigated by in vitro immersion test, and it was found that the corrosion rate was effectively decelerated within 10 days. In summary, we studied the effects of reaction conditions for preparing Mg-P coatings on the surface of Mg-Zn-Y-Nd alloy by a chemical conversion method and effectively improving the corrosion resistance of Mg-Zn-Y-Nd alloy.