Reciprocating Sliding Friction Behavior and Wear State Transition Mechanism of Cylinder Liner and Piston Ring

To investigate the wear time-varying characteristics of cylinder liner cast iron, dry sliding wear experiments were conducted on the cylinder liner and piston ring at room temperature. The surface and interface morphologies of the cylinder liner wear scar were analyzed using a white light interferometer, scanning electron microscope (SEM), and transmission electron microscope (TEM) at different wear times. The results indicate that the wear state of cylinder liner cast iron changes over time. Based on the change in friction coefficient, the wear process can be divided into three stages: low wear stage, stable wear stage, and severe wear stage. The shedding of graphite and its self-lubricating effect contributes to the low friction coefficient and wear rate observed in the low wear stage. The formation of a friction layer leads to the wear entering a stable stage, where adhesive wear of pearlite occurs. As the friction layer and the phosphorus eutectic wear and fall off, the wear process of the cylinder liner intensifies, with delamination wear becoming the primary wear mechanism. This study reveals the wear degradation mechanism of cylinder liner cast iron from the perspective of microstructures, offering valuable information for predicting wear and optimizing the microstructure of cylinder liners and piston rings.