Research On The Friction And Wear Behavior Of Cast-iron Cylinder Liner With Different Micro-textures

With the enhancement of strengthening index in marine diesel engine,the friction and wear performance of piston ring and cylinder liner(PRCL)directly affects the fuel economy,thermal efficiency,durability and even service life of the diesel engine.Under the harsh conditions,PRCL interface inevitably endures heavy duty load,especially near the top dead center.When the worn interface of PRCL is continuously affected by the high temperature and high explosive pressure,it will cause a series of problems,such as increased frictional work,accelerated wear rate,even serious tendency to scuffing.In general,the wear and scuffing problems of PRCL can be properly suppressed by surface modification methods.Surface micro-textures are a kind of dimples or grooves with dimensions ranging from tens to hundreds of microns which are machined on the surface of frictional pair.It is an effective way to improve the tribological performance of PRCL.The micro-textured morphology has uncrossed and non-connecte d grooves.These arrangements can effectively store lubricating oil and abrasive particles which facilitate the formation of additional hydrodynamic pressure and minimize the abrasive wear on the mating surface.In this paper,circular,elliptic and square micro-textured morphologies were machined on the cast-iron cylinder liner by reciprocating electrolyte jet with prefabricated-mask technology(REJP).Then through the PRCL testing machine of friction and wear evaluation,friction coefficient,wear loss and anti-scuffing time of the different micro-textured cylinder liner were measured under different temperatures,different loads and starvation conditions.Finally,frictional characteristics and.stress distribution of the micro-textured cylinder liner were extracted.Worn morphologies of different micro-textured cylinder liner were analyzed,then worn mechanism were also discussed.It can provide some design guidance of the micro-textured surface for the cast-iron cylinder liner.The main conclusions are as follows:(1)Friction coefficient and wear depth of different micro-textures presented a decreasing trend as the temperature increased,friction coefficient and wear depth of circular,elliptic and square micro-textured cylinder liners were lower than those of the non-textured cylinder liner.Friction coefficient and wear depth of circular micro-textured cylinder liners were the smallest among the micro-textured cylinder liners.While friction coefficient of different micro-textures firstly decreased and then increased as the load increased.Friction coefficient of different micro-textures is the smallest at 50MPa.(2)Based on Empirical Mode Decomposition(EMD),friction force variation of different micro-textures was analyzed,and friction characteristics of different micro-textures were also obtained.According to friction reduction of three divided stroke sections,circular micro-texture reduced the friction force in the front 1/3 stroke and the middle stroke,while square micro-texture reduced the friction force in the rear 1/3 stroke.(3)Different micro-textured morphology analysis showed that element carbon accumulated on the worn surface of the cylinder liner.Graphite released from micro-dimples changed the graphite distribution.This may be one of the important reasons that micro-textured cylinder liner had less friction coefficient and wear depth compared to non-textured cylinder liner.(4)The order of anti-scuffing time was elliptic micro-texture>circular micro-texture>square micro-texture>non-texture cylinder,indicating that the existence of micro-texture can significantly improve the anti-scuffing cylinder performance of the cylinder.There was a large stress distribution on the edge of the concave pit of the micro-texture,in which the square micro-texture>circular micro-texture>elliptic micro-texture.It may be the reason for the better anti-scuffing cylinder performance of the elliptic micro-texture.