Improvement of tribological and fatigue properties of casting magnesium alloy AZ91 modified laminate DLC coating

Abstract

In recent years, magnesium alloys have been widely used because of their lightweight and easy recycling. However, magnesium alloys are inferior in wear resistance. Therefore, it is necessary to improve this property to use magnesium alloys for more machine parts. In this study, DLC (Diamond Like Carbon) coating, which is well known for its high hardness, low friction and excellent wear resistance, was performed on a cast magnesium alloy AZ91. However, it is difficult to perform hard coating like DLC on the soft materials like magnesium alloys in terms of adhesion strength between the substrate and the coating. So, in this study, in order to acquire the high adhesion strength, DLC coated process was performed by using UBMS (Unbalanced Magnetron Sputtering) method, and inter-layer which was doped Tungsten was formed on the substrate, and on the inter-layer two kinds of DLC coatings were laminated for nano order. Wear tests and fatigue tests were carried out. Magnesium alloy coated DLC indicated excellent wear friction. Furthermore, the fatigue reliability was elevated by DLC coatings compared with substrate only.