Cold arc cladding of aluminum coatings on AZ61 magnesium alloy: A comparative study

The corrosion resistance and wear resistance of magnesium alloys seriously restrict their applications in industry. The objective of this work is to provide a comprehensive understanding, including parameters, microstructure and properties, of the cold arc cladding process of aluminum coatings on AZ61 magnesium alloy. Three kinds of cladding wires, Al-Mn alloy (AlMn1), Al-Si alloy (AlSi5) and Al-Mg alloy (AlMg5), were cladded on the surface of AZ61 magnesium alloy by pulsed direct current (P-DC) cold arc for a comparative study. The study revealed a correlated relation between the clad geometry and the heat input during the deposition process. The microstructure and composition of the coatings were carefully studied by SEM, EDS and XRD. The properties of the coatings were studied by the micro-hardness, wear resistance and electrochemical corrosion test. The Al-Mn alloy coating has the highest hardness, which is three times that of the AZ61 magnesium matrix. The Al-Si alloy coating has the lowest wear rate, which is about 13.9% of the Mg matrix. The corrosion performance of the Al-Mg alloy coatings is significantly improved by alpha-Al phase compared to the Mg matrix.