Study On Microstructure And Property Of The Wear-resisiting And Self-lubrication Coatings

In order to improve the tribology property of the machine part, theexperiment choose NiCr coated Cr3C2cermet powder, Ni60 alloy, Ni coatedMoS2and Ni coated graphite as solid lubricating material, two self-lubricatingcoatings(MoS2-Cr3C2 and graphite-Cr3C2) are prepared using HVOF, themicrostructure and tribology property of the two self-lubricating coatings arestudied.The results indicate that the Ni-coated powders can prevent the burningloss of the lubricating agent MoS2 and graphite; the microstructure of theself-lubricating coating is loose, the porosity of the heterogeneity particles ishigh, porosity diameter is big. Because the half melt ceramic particles haveerosioneffect onthealreadyformedcoating,different kinds ofself-lubricatingphases in the raw spray materials will cause different number of self-lubricating phases in the coating. The inducing of self-lubricating phases havegreat effect on the coatings'anchoring strength and micro-hardness. In theMoS2 coating, the micro-hardness and anchoring strength are increasing withthe increasing of Cr3C2,but reducing with increasing of MoS2 ; the fricationcoefficient, rate of wear of the coating and the rate of wear of the pair ofelement are great effected by the content of MoS2and Cr3C2 in the raw spaymaterial,thecoatingcanrealizeself-lubricating.Ingraphite-Cr3C2coating,the proportion of the raw spray material have no obvious effect on themicro-hardness, anchoring strength, rate of wear of the coating and the rate ofwearofthepairofelement,thecoatingcannotrealizeself-lubricating.Under the conditions of this experiment, the anchoring strength of theMoS2-Cr3C2 coating can reach 15MPa, micro-hardness can reach 300HV, canmeet the demands of general use. When the content of MoS2-Cr3C2coating is8.8wt%, Cr3C2 is 30wt%,the friction coefficient of the coating is 0.3, rate ofwear is 4.9×10-3, rate of wear of the pair of element is 15.7×10-3mg/m,theeffect of the self-lubricating is good. The realization of the self-lubricatingincludes two procedures: first is in the frication process the self-lubricatingphases in the coating exfoliated and fill the coating which makes the coatingflat , then the self-lubricating phases filled in the hollowly area in the coatingaretransferred tothesurfaceofcoatingandformthelowshearstrengthfilm.