Role of Surface texture on Friction and Transfer Layer Formation when Mg-8Al Alloy Slid Against Steel Counterface

Surface texture influences friction and transfer layer formation during sliding. In the present investigation, various kinds of surface texture with varying roughness were produced on steel plates. Pins made of Mg-8Al alloy were then slid against the prepared steel plates using inclined pin-on-plate sliding tester to understand the role of surface texture of the harder surface and load on coefficient of friction and transfer layer formation under both dry and lubricated conditions. Normal loads were varied from 1 to 120 N during the tests. Tests were conducted at a sliding velocity of 2 mm/s in ambient conditions. Scanning electron micrographs of the surfaces in contact for both the pins and plates were obtained to understand the morphology of the transfer layer. Surface roughness parameters of the steel plate were measured in the direction of the sliding on the bare surface away from the wear tracks using an optical profilometer. It was observed that the coefficient of friction and transfer layer formation are strongly dependent on surface texture and independent of surface roughness (Ra) of steel plate. Among the surface roughness parameters, the mean slope of the profile was found to explain the variations best. The plowing component of friction was highest for the surface that promotes plain strain conditions while it was lowest for the surface that promotes plane stress conditions near the surface.