Evolution mechanism of wear characteristics of cylinder liner and piston ring under starved lubrication condition

This study investigates the sliding wear behavior of cylinder liners and piston rings under starved lubrication conditions, using a step-loading method to analyze the wear state transition of the cylinder liner. The wear scar surface and interface characteristics under different wear conditions were examined using optical microscopy (OM), white light interferometry, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The study also explores the mechanism behind the wear state transition. The results show that the friction coefficient initially increases, then decreases, and increases again with increasing load. The initial rise is attributed to an increase in surface roughness. As the tribo-layer forms, the friction coefficient gradually decreases. However, with a further increase in load, the tribo-layer begins to wear, leading to scuffing and a rapid increase in the friction coefficient. Graphite and phosphorus eutectic in the cylinder liner are the primary contributors to crack formation in both the tribo-layer and the substrate. Furthermore, the tribofilm formed on the initial wear scar surface also contributes to crack formation.