Research Of Friction And Wear Behavior Of Diesel Engine With High-strength Coefficient

The cylinder liner/piston ring system is one of the key components of internal combustion engine, whose properties indicated the reliability of engine. Recently years, the demands of cylinder diesel engine with high enhancement factor increased due to the speed and detonation pressure raised, and the abrasive resistance of cylinder materials under high temperature and pressure need to be improved. So, to study the friction and wear of the cylinder liner/piston ring system is significant and may improve the properties and longevity of internal combustion engine.In this study, the operation of diesel cylinder liner/piston ring with high enhancement factor has been simulated by the tribology systems guiding ideology and wear conditions-form simulation principles. Friction and wear behavior of the four cylinders paired with piston ring (sprayed molybdenum) have been analyzed. Experiment is conducted by homemade reciprocating friction and wear tester, in the parameters of contact surface pressure of 93MPa, speed 100r/min, working temperature 100℃, and wear time 24 hours. The four cylinder materials are boron-phosphorus alloy cast iron, boron-phosphorus alloy cast iron after laser hardening, alloy cast iron after austempering, and molybdenum-nickel alloy cast iron.The conclusion is show as follows:Integrated abrasion resistance of alloy cast iron after austempering preformed best, then is molybdenum-nickel alloy cast iron. The third one is boron-phosphorus alloy cast iron after laser hardening. Its abrasion loss is lower however it abraded the coupled material most seriously. And the integrated abrasion resistance of traditional cylinder materials-boron-phosphorus alloy cast iron preformed worst.Wear mechanism of the four cylinders have been approached also. The abrasion resistance factors including matrix, content and distribution of hard phase, graphite morphology, honing parameters and the organization of laser hardening have been studied.The matrix of alloy cast iron after austempering is uniform bainite and a small amount of residual austenite, and hard phase distributed uniform among grains which had not been effect of honing. The micro-hardness of surface is high, and the graphite morphology in matrix is chrysanthemum-shaped and flake. These factors are conductive to the improvement abrasion resistance of cylinder. So the abrasion resistance of cylinder is a matrix, hard phase, honing, graphite, and the hardness result of multiple factors.