Friction and wear properties of permanent mould cast AZ91D magnesium alloy

The friction and wear properties of permanent mould cast AZ91D magnesium alloy were investigated under dry reciprocating sliding conditions by using a ball-on-disk machine. The results indicated that the wear resistance of the alloy was relatively poorer than those of the other commercial alloys. The wear rate per sliding distance continuously decreased while the wear rate per testing time linearly increased with the increase in reciprocating frequency. The friction coefficient slowly decreased with the frequency. As the load increased, both the wear rates increased while the friction coefficient first decreased, then increased and finally decreased again. Under low frequency or load, oxidation wear or micromachining wear dominated. As the frequency or load increased, the dominative mechanism changed in turn to plastic deformation induced wear, severe deformation accompanied by severe adhesion wear and smear wear. The work hardening and thermal oxidation of the contact surfaces played an important role for the wear behaviour.