Study On Molybdenum Disulfide Doped Magnesium Silicate Hydroxide Composite Wear-resistant Coating

This article mainly focuses on the problem of serious wear of the sliding bearing of the fuel pump,and aims to improve the tribological performance of the composite solid wear-resistant coating on bearings.It is proposed to add magnesium silicate hydroxide（MSH）in the coating to improve its performance in RP-3 aviation kerosene and under dry friction conditions.The effects of different contents of natural serpentine,MSH with different micro-morphology and different contents of MSH on the tribological properties of the coating were studied.The tribological performance experiments of the best formulation coating under different working conditions were analyzed,and the anti-friction and anti-wear mechanism of the coating was proposed.The composite solid wear-resistant coating was prepared on the basis of the existing coating formula and preparation process in the laboratory.It was found that adding natural serpentine powder could improve the wear resistance of the coating,but it was not all beneficial to the coefficient of friction（COF）of the coating and the wear of the mating ball.MSH nanoparticles with different microscopic morphologies were synthesized hydrothermally.It was found that the tribological property of the coating with uniform flake morphology MSH powder,is betterer than that with uniform tubular MSH or flake and tubular mixed MSH powder.The optimised tribological performance is obtained when the mass ratio of MSH:Mo S₂:graphite:Al₂O₃:Ce F₃:PI:DMF=2.5:2.5:1:0.6:0.2:6.6:7.2.The tribological properties of the optimized coating lubricated with or without kerosene were investigated under different loads,different speeds and multiple start-stop conditions.It was found that whether it is an oil immersion test or a dry friction test,the COF of the coating decreases,and the wear rate of the coating decreases as the load increases.With the increase of the speed,the COF and the wear rate of the coating decreased during the oil immersion test,while the COF and the wear rate of the coating increased at the same time during the dry friction test.With the increase of the number of starts and stops,the wear scar diameter of the mating ball and the amount of coating wear slightly reduced.However,compared with the oil immersion experiment,the effect of multiple starts and stops in the dry friction experiment is less significant.The anti-friction and anti-wear mechanism of the coating was analyzed by scanning electron microscope（SEM）and energy spectrometer（EDS）.The coating material is absorbed and embedded on the surface of the mating ball to form a transfer film,which reduces friction and wear.The composition of the transfer film in the lightly worn area is graphite,while that in the severely worn area includes graphite,MSH and Mo S₂.In conclusion,MSH with uniform flake morphology can effectively improve the tribological properties of the coating.A transfer film with MSH forms in the severely worn area on the mating ball which reduces the friction and wear.