Abstract

This study investigates the influence of the morpho-dimensional (porosity, solidity, circularity, eccentricity and Feret diameter) evolution of pores, e.g. solid lubricant reservoirs, on the tribological behaviour of impregnated materials. In addition, a new parameter, the mean carbon intensity inside each individualised pore, was proposed to further understand the solid lubrication phenomenon in sintered composites. PM techniques produced low alloy sinter-hardened steel specimens vacuum-impregnated with graphite particles. Interrupted incremental load tests (7 N increments every 10 min) were used to study the evolution of open pores (solid lubricant reservoirs) in the wear scars. During tribological testing, the impregnated pores get sealed. The narrow sections connecting pores deform and close, reducing porosity and the Feret diameter of individual pores. Then, pores get smaller and sealed to the point where the lubricity regime ends. Small and narrow pores retain the impregnated graphite better, slowly releasing it and helping to maintain the lubricity regime.