Some mechanisms in the unlubricated running-in behaviour of an AlSiCu alloy against 52100 steel

Friction coefficients of samples of an AlSiCu alloy sliding against 52100 steel were determined on a tribometer. The alloy was chosen to represent a generic class of materials having wear resistant microstructures in which hard particles are contained within a softer metal matrix. These results together with microstructural observations from these samples and from comparative tests with silicon and 2024-T4 alloy led to a sliding running-in (break-in) model which takes account of the initial state of the surface, whether etched or polished