Study on the Influences of Surface Coatings under Boundary Lubrication on the Frictional Performance of a Piston Skirt
The effects of surface solid lubricating coatings on the friction and wear performance of piston skirts under boundary lubrication conditions were studied,so as to provide supports for the design of piston skirt coatings for high-duty internal combustion engines.A self-built reciprocating friction and wear testing machine was utilized for conducting wear experiments with real cylinder liner and piston skirt samples.38CrMoAl steel mirror nitride cylinder liners and two types of coated pistons,namely graphite and tungsten disulfide coated pistons(aluminum-silicon alloy matrix)were used in the experiments.The friction coefficient and wear of the two piston skirt-cylinder liner pairs were obtained under different working conditions,and the wear surface was also analyzed.The results show that under all working conditions,the wear amount and friction coefficient of the tungsten disulfide-coated piston skirts are smaller than those of the graphite-coated piston skirts.Under the three loading conditions of 15,25 and 35 MPa,the friction coefficients and wear amounts show an upward trend for both friction pairs as the load increases.When the test temperature increases from 120℃to 150℃,the decomposition of zinc dialkyl dithiophosphate(ZDDP)additive in the lubricating oil is promoted,and the friction coefficient and wear decreases.Under the load of 35 MPa,the friction coefficient and wear amount increase again when the test temperature increases from 150℃to 180℃.It is considered that the abrasive wear caused by the exposure of silicon particles in the piston skirt increases under the combined action of high temperature and high load.
boundary lubricationpiston skirtgraphitetungsten disulfidefriction and wearzinc dialkyl dithiophosphate(ZDDP)
国家科技期刊平台
NSTL
万方数据
