Sliding wear of cast zinc-based alloy bearings under static and dynamic loading conditions

The lubricated wear behaviour of cast journal bearings, produced from a series of zinc-based alloys and SAE 660 bronze as a reference material, was investigated under both static and dynamic loading conditions using a bearing test rig. All of the zinc-based alloys had higher wear resistance than the SAE 660 bronze. Among the zinc-based alloys, the wear resistance of the monotectoid-based alloys was superior to those based on near-eutectoid composition, and the best wear performance under both static and dynamic loading conditions was obtained with ZnAl40Cu2Si1 alloy. Copper content affected the wear resistance of monotectoid zinc-based alloys. Under dynamic loading conditions, it increased with increasing copper content up to 2%, but declined thereafter. Tensile properties and hardness of the monotectoid alloys were also affected by their copper content. Loading conditions had a strong influence on the wear rate. Under static loading conditions, as-cast zinc-based alloys showed higher wear resistance than the equivalent heat-treated alloys, but this behaviour was reversed for dynamic loading. Possible reasons for this are briefly discussed.