Study Of Tribo-behavior Of Dual Textured Piston Ring-cylinder Liner Surfaces

Piston ring-cylinder liner(PRCL)is an important mating pair of diesel engine.Its friction and wear performance directly affect the mechanical efficiency,reliability and service life of the whole machine.With the various strengthening indexes of marine diesel engines,the contact pressure and temperature of the PRCL interface continue to rise.The harsh working conditions have led to the increasing friction power consumption and some wear and scuffing problems are becoming more prominent.These problems have prompted researchers to continuously develop new friction-reduction and wear-resistant technologies.Surface texturing of the PRCL is an important means to improve the tribo-behavior.This thesis proposed a method by separately texturing the surfaces of piston rings and cylinder liners to improve the friction and wear performance.Two dual-textured piston ring-cylinder liner surfaces have obtained,i.e.,microtextured piston ring-microtextured cylinder liners(MP-MC)and solid lubricant filled microtextured piston ring-solid lubricant filled microtextured cylinder liners(SMP-SMC).Then the variation of friction and wear performance of MP-MC and SMP-SMC was obtained in comparison with non-textured piston ring-non-textured cylinder liner(NP-NC)under different temperature,load and starvation conditions.The surface morphology,distribution of elements and tribo-chemical reaction products were analyzed to discuss the friction-reducing and wear-resistant mechanism of the dual-textured PRCL.This research will provide technical support and theoretical basis for the design of dual-textured mating pair.The obtained conclusions are as follows:(1)The micro-textured piston ring and micro-textured cylinder liner were prepared using the reciprocating electric jet processing technology developed by the research group.Molybdenum disulfide was deposited in the micro dimples of the micro-textured piston ring by cathodic reduction of thiosulfate.Composite solid lubricant of nickel-based molybdenum disulfide/titanium aluminum carbide was deposited in the micro dimples of micro-textured cylinder liner using composite electroplating technology.(2)As the load increased from 25 MPa to 75 MPa,wear depth of NP-NC,MP-MC and SMP-SMC increased.The friction coefficient of NP-NC and SMP-SMC decreased with increasing load,while the friction coefficient of MP-MC decreased and then increased with increasing load.Compared to NP-NC and MP-MC,SMP-SMC always had the lowest friction coefficient and wear depth under different loads.Surface topography and EDS analysis showed that the solid lubricant of SMP-SMC overflowed from the micro dimples and formed some fine sliding textures on the worn cylinder liner.(3)As the temperature increased from 150℃ to 250℃,friction coefficient and wear depth of NP-NC,MP-MC and SMP-SMC both decreased.Compared to NP-NC and MP-MC,SMP-SMC always had the lowest friction coefficient and wear depth under different temperatures.Surface analysis of SMP-SMC showed that the oxidation of the layered titanium aluminum carbide could inhibit Mo S2 oxidation and ZDDP decomposition.The main components of the tribo-film on the cylinder liner at 250°C were Mo S2,Mo O3,Mo Ox Sy,Fe2O3,Fe S,Zn O,Zn S,sulfate and phosphate.(4)The anti-scuffing performance showed that the anti-scuffing time of NP-NC,MP-MC and SMP-SMC was about 10 min,38 min,and 179 min,respectively.The analysis showed that the micro-texture and overflowed solid lubricant could suppress the large-area adhesive and abrasive wear on the cylinder liner.Solid lubricant could still remain in the micro dimples on the SMP-SMC surface after the cylinder liner was scuffed.