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.
|