【作者】 戴基卉；

【导师】 熊党生；

【作者基本信息】 南京理工大学 ， 材料学， 2010， 硕士

【摘要】 摩擦磨损造成的损失巨大,汽车发动机因摩擦而损失约30%的功率,其中缸套-活塞环摩擦副间的摩擦损失占了发动机总摩擦损失的19%,而磨损导致活塞环-缸套配副频繁更换,损失严重。本文改变活塞环表面结构以期改善表面润滑状态,并引入耐磨润滑涂层,协同作用改善活塞环表面摩擦学性能。采用Nd：YAG脉冲激光器在合金铸铁及表面镀铬活塞环外圆面进行微造型化处理,获得直径分别为125μm、150μm、200μm,深度分别为25μm、40μm、55μm,密度为2.1%～11.04%的微造型阵列。模拟实际活塞环-缸套往复运动状态,在自制往复摩擦磨损试验机上测试微造型化活塞环的摩擦学性能,并对微造型参数进行优化。采用电镀方法在铸铁活塞环外圆面镀覆厚约40μm的铬层再进行激光表面微造型处理。在微造型化合金铸铁活塞环表面进行化学镀银,获得微造型内储存银、表面覆盖厚约60μm银镀层的复合涂层。用光学金相显微镜、扫描电镜观察镀层表面及截面形貌：用X射线衍射仪和能谱仪(EDS)对镀层进行物相和成分分析。测试镀层／微造型协同作用配副的摩擦学性能,并采用扫描电镜以及金相显微镜观察磨痕形貌。实验表明：合金铸铁活塞环表面微造型化处理改善了配副的摩擦学性能。油润滑条件下,微造型化处理使摩擦系数降低15%～40%,磨损率降低50%左右,磨损寿命提高2倍。微造型化存在最佳参数使配副摩擦学性能最好：低载(50N,100N)作用下,最佳直径为150μm,最佳深度为35μm；高载(200N)作用下,最佳直径为200μm,最佳深度为50μm；各载荷下,最佳密度为4.9%。活塞环表面镀铬／表面微造型协同作用使摩擦副的摩擦系数降低了20%,磨损率降低了两个数量级；优化镀铬／微造型化参数表明油润滑条件下微造型密度为4.9%的配副摩擦学性能最好。活塞环表面化学镀银后,摩擦系数降低20%～50%,磨损率升高一个数量级。微造型化／镀银使活塞环的摩擦系数进一步降低16%～33%,磨损率降低14%～60%,磨损寿命提高3倍以上。活塞环表面微造型技术／涂层复合改性与微造型和涂层分别单独作用相比,改善活塞环-缸套配副的摩擦学性能效果更好。更多还原

【Abstract】 The lost caused by friction and wear is huge. There is about 30% power of automobile engine lost because of friction,19% of the power loss is come from the piston ring-cylinder liner pair. This important pair of engine often damaged because of wear. In this paper, the surface micro structure of piston rings is changed in order to change lubrication regime of surface, and wear resistant and lubricant film is add into the surface, to improve the wear resistant property.Using a Nd:YAG pulsed laser to texture the out surface of piston rings, then get microdimple array with different diameter, depth, density. The textures with different parameters are shown as follows:dimple diameter(125μm、150μm、200μm),dimple depth(25μm、40μm、55μm), dimple density(2.1%～11.04%). Simulateing the reciprocating motion of piston rings-cylinder liner pair, test tribological properties of the pair on a self-made friction and wear testing machine, and find the optimum parameters.Electroplate Cr film with a thickness of 40μm on the out surface of piston rings. Then texture the Cr coated rings. Make Ag film with a thickness of 60μm on the surface of textured piston rings by chemical depositing. Observe the surface and section of films by optical microscope and SEM. Analysis the phase by XRD and EDS. Test the tribological properties of the coated/texturing cooperating effect pair. Then observe the wear truck morphology by optical microscope and SEM.The test shows that the tribological property of the pair is proved by laser texturing. In oil lubricating condition, the friction coefficient decreased about 15%～40%, wear rate decreased about 50%, its wear life is prolonged 2 times.There are optimum parameters that make the pair show the best tribological property:Under low load, the optimum diameter is 150μm, optimum depth is 35μm. Under high load, the optimum diameter is 200μm, optimum depth is 50μm.The optimum density is 4.9%.The wear rate of Cr coated/texturing piston rings decreased two orders of magnitude, while friction coefficient decreased 20%.The optimum density of Cr coated/texturing cooperating action is 4.9%, which is the same as texturing action alone. The wear rate of Ag coated piston rings increased one order of magnitude, while friction coefficient decreased 20%～50%。Piston rings with texturing and Ag coatings cooperating effected, its friction coefficient decreased 16%～33%, the wear rate decreased 14%～60%, its wear life prolong 3 times.Compared to surface texturing and coatings action respectively, the effect of texturing and coating cooperating action can improve the tribological properties of piston rings-cylinder liner pair more effectively.更多还原