Study On Influence Of Copper Element On The Tribological Properties Of Cylinder Liner-piston Ring

The cylinder liner-piston ring(CLPR)assembly is one of the core friction pairs for energy conversion in a diesel engine,and its performance affects the efficiency,service life,reliability and economy of the diesel engine.Relevant studies have shown that the friction loss of CLPR accounts for 40%-60% of the overall friction loss of the diesel engine.At the same time,due to the harsh working environment of CLPR,the faults caused by it also account for a large proportion of the faults of the marine engine.In recent years,with the development of high-power diesel engines,the pressure and temperature of the combustion chamber and the linear speed of the piston group have gradually increased,which poses new challenges to the performance of CLPR.Therefore,it is of great significance to carry out research on friction reduction and anti-wear of CLPR friction pair to improve the reliability,service life and fuel economy of diesel engines.This thesis takes the CLPR pair of diesel engine as the research object,focusing on the effect of different forms of copper element addition on the tribological properties of CLPR friction and its mechanism.It mainly includes processing copper-infiltrated modified layers of different thicknesses on the surface of the cylinder liner,using nano-copper particles as a lubricant additive for the lubrication of cylinder liner-piston ring,and using surface texture and nano-copper additives to optimize CLPR friction pair.The characteristic parameters under different operating conditions were comprehensively compared,and the influence of copper element on the performance of CLPR friction pair was systematically analyzed.The research results show that the infiltration of copper element to modify the friction surface and the optimization of nano copper used for lubrication can effectively improve the tribological properties of CLPR friction pair.The copper infiltration layer is processed on the surface of the cylinder liner material,and the anti-friction and wear resistance effect is particularly significant under high load and dry friction conditions.The copper infiltration layer with a thickness of 40μm reduces the friction coefficient and wear amount by 30.86% and 38.57%,respectively.Adding nano-copper as an additive to the lubricating oil can effectively reduce the friction and wear of CLPR friction pair,and its friction coefficient can be reduced by21.21% at the highest.When the 2% nano-copper additive and surface texture technology are simultaneously applied to the optimization of the tribological properties of CLPR,the synergistic effect of the two further improves the tribological performance of CLPR,especially under heavy load conditions.The friction coefficient decreased by 22.92% when the nano-copper lubricating additive and the surface texture of the cylinder liner pits worked together.The above research lays the foundation for the tribological design of CLPR.