Study on micro-arc oxidation coating of magnetic metal powder composite magnesium alloy

Abstract

Purpose The purpose of this paper is to prepare composite micro-arc oxide coatings with better wear resistance and corrosion resistance. Design/methodology/approach A nickel powder composite micro-arc oxide film was prepared on the surface of the magnesium alloy by the method of organically combining ultra-fine Ni powder with micro arc oxidation film layer. In this experiment, the changes in the corrosion resistance and microstructure of the composite film layer after adding Ni powder were studied, and the effect of the addition of glycerin on the corrosion resistance of the film layer was analyzed. Findings The results show that the ultra-fine nickel powder was successfully prepared by the liquid phase reduction method, and the micro-arc oxidation process was modified under the optimal addition amount. The surface of the micro-arc oxide film made of ultra-fine nickel powder was found by SEM to have smooth surfaces and few holes. According to X-ray diffraction analysis, the phase composition of the micro-arc oxide film layer was Mg, Ni, NiSiO4, MgNi (SiO4) and Mg2SiO4. According to the results of electrochemical tests, the corrosion resistance of the micro-arc oxidation composite film layer was improved after the addition of ultra-fine Ni powder, the corrosion current was greatly reduced and the impedance has been improved. And after adding glycerin, the surface of the film layer becomes denser, and the corrosion resistance of the micro-arc oxide film is significantly improved. Originality/value Through this experimental research, a micro-arc oxide coating of powder composite magnesium alloy was successfully prepared. The corrosion resistance of the micro-arc oxidation film layer has been improved, and certain functions had been given to the micro-arc oxidation composite film, which has increased the application field of magnesium alloys.

Varied corrosion evolution behavior of pure Mg, AZ31 and AZ91 magnesium alloys in phosphate buffer solution

“…The corrosion product layer also plays a key role in shaping the corrosion behavior of pure Mg and its alloys, especially at an extended corrosion time. With corrosion product layer covering, the corrosion mechanism of materials may see a significant difference (Su et al , 2020; Huang et al , 2019). Although there are available works on the corrosion behavior of pure Mg, AZ31 and AZ91 in simulated human body fluids, they are mainly focused on the CR evaluation and characterization of corrosion products.…”