Fabrication of Cr coating on AZ31 magnesium alloy by magnetron sputtering

Chromium-plating is considered an effective method to improve surface properties of metal materials. Magnetron sputtering was applied to prepare Cr coating on AZ31 magnesium alloy and the influence of bias voltage on properties of Cr coating was investigated. The obtained coatings present an (110) preferred texture and have a developed columnar structure. With increasing bias voltage, the surface structure of Cr coating becomes denser. All of the Cr-coated AZ31 have much higher surface microhardness than bare AZ31. The Cr coating deposited on AZ31 at bias voltage of −150 V has a higher corrosion potential than others. The result of the immersion test shows that it decreases the damaged area compared with bare AZ31. The failure of the coated AZ31 is mainly attributed to the existence of through-thickness defects in the coating.