激光表面织构微坑形貌及面积占有率对氮化气缸套摩擦学性能的影响

Effect of Surface Texture Micro-pit Morphology and Area Density on Tribological Properties of Nitrided Cylinder Liner

针对氮化气缸套由于自身存在表面应力高、易变形等使其难以满足高强化内燃机气缸套要求的问题,以氮化气缸套-PVD活塞环为研究对象,采用Nd-YAG脉冲激光器在氮化气缸套表面进行织构化处理,研究脉冲激光参数对气缸套表面微织构微坑形貌及面积占有率对摩擦副摩擦磨损性能的影响,并分析其影响机制。发现织构微坑直径随激光能量密度、脉冲次数、离焦量增加而增大,而微坑深度随能量密度、脉冲个数、离焦量的增加呈先增大后减小的趋势。不同面积占有率织构对气缸套-活塞环摩擦副均具有减摩耐磨作用,与无织构缸套摩擦副相比,微织构气缸套的摩擦因数降低10.07%~1.58%;磨损量降低26.71%~46.19%;微织构气缸套对应的活塞环试样磨损量降低10.12%~50.19%;微织构气缸套的拉缸时间提高了2.1~2.8倍。最低摩擦因数和磨损量及最佳抗拉缸性能均在面积占有率为10%的织构摩擦副获得。微织构改善气缸套摩擦副摩擦磨损性能的机制为贮存润滑油,减少摩擦副接触面积以及捕捉磨屑,减小磨粒磨损。获得了高强化条件下氮化气缸套织构化对其摩擦学性能的影响规律,可为开发高强度内燃机提供试验支持。

Nitrided cylinder liner was difficult to meet the requirements of new high strength internal combustion engine because of its high surface stress and easy deformation.Micro surface textures with varied area density were prepared on the surface of nitrided cylinder in cylinder liner-PVD piston ring test rig by Nd-YAG pulse laser.The effect of pulse laser parameters on the morphology of micro-pit on the surface of the cylinder liner and the friction and wear properties of the friction pair were studied,and the influence mechanism was analyzed.It was found that the texture pit diameter increased with the increased of laser energy density,pulse number and defocusing distance,while the pit depth increased first and then decreased with the increased of laser energy density,pulse number and defocusing distance.Different area density texture had anti-friction and wear-resistant effect on cylinder liner-piston ring friction pairs.Compared with Un-textured cylinder liner friction pairs,the friction coefficient of micro-textured cylinder liner decreased by 10.07% ~ 21.58%.The wear loss decreased by 26.71% ~ 46.19%;The wear of piston ring specimen corresponding to micro-textured cylinder liner decreased by 10.12% ~ 50.19%;The cylinder scuffing time of micro-textured cylinder liner was increased by 2.1 ~ 2.8 times.The minimum friction coefficient,wear amount and the best anti-scuffing performance were obtained in the textured friction pair with an area density of 10%.The mechanism of micro-texture improving friction and wear performance of cylinder liner friction pair was to store lubricating oil,reduce the contact area of friction pair,capture debris resulted in the reduction of abrasive wear.The influence of textured nitrided cylinder liner on its tribological properties was summarized under high strengthening conditions,which provided experimental support for the development of high strength internal combustion engine.