Study On Microstructure And Properties Of Plasma Deposition Superallov Base Wear Resisting And Self Lubricating Composite

Continuous extrusion has a widespread application in the field of non-ferrous metal processing,however,under high temperature and high contact stress of the working environment.the key parts of extrusion press should have characteristics such as high temperature enduring high strength,high temperature wear resistance and antifriction performance.Therefore,choose superalloy Inconel 718 which has the best yield strength under 650 ? in all wrought superalloy,and has good anti-fatigue and anti-oxidation properties as the matrix,choose high melting point,high hardness and high temperature stability TiC as wear resisting enhancement phase.Choose CaF₂ which has layered structure with low shear strength,and ductile-brittle transition at 600 ? as self lubricating phase.This kind of superalloy based wear resisting and self lubricating composite should be able to meet the working condition of the key parts of the continuous extruder.Since the mechanical processing of the superalloy is very difficult,plasma deposition rapid forming were chose to fabricate the composite.This is undoubtedly beneficial to the formation of complex components and the uniform distribution of each component in composites.In this paper,Inconel 718 powder,Inconel718-12Ti-10 nickel coated graphite-15 nickel coated calcium fluoride?wt.%?,Inconel718-12Ti-10 nickel coated graphite-20 nickel coated calcium fluoride?wt.%?,Incone1718-12Ti-10 nickel coated graphite-25 nickel coated calcium fluoride?wt.%?and Incone1718-12Ti-10 nickel coated graphite-30 nickel coated calcium fluoride?wt.%?powders blend were used as raw materials to produce the superalloy based wear resisting and self lubricating composite by plasma deposition rapid forming.XRD,OM,SEM,EDS were used to analyze the microstructure and phase composition of Inconel 718 samples and composites.The results showed that the plasma deposition rapid forming Inconel 718 samples consist of ?"-Ni₃Nb high temperature enhancement phase and y-?Ni,Fe?solid solution;and the composites consist of TiC wear-resisting phase,CaF₂ self lubricating phase,y"-Ni₃Nb high temperature enhancement phase and y-?Ni,Fe?solid solution.The microstructure of the composites was refined and dense,TiC and CaF₂ uniformly distributed in ?-?Ni,Fe?matrix and the primary TiC phase is coated by ?"-Ni₃Nb.The microhardness value of the composites was measured by microhardness tester.The results showed that the hardness of the composites decreased with the increase of CaF₂ content.However,the microhardness value of all composites are significantly higher than Inconel 718 samples.The pin-on-disk room temperature wear tester was used to measure the room temperature dry sliding wear property.The results showed that the wear resistant properties of Inconel 718 is poor.Since TiC played a key role in the wear resistance of the composites,the wear resistant properties of the composites were obviously better than Inconel 718 samples.And with the increased of CaF₂ content,the room temperature wear resistant properties of the composites become better.The ball-on-disk high temperature wear tester was used to measure the high temperature dry sliding friction and wear properties.The results showed that the surface of the Inconel 718 sample has experienced severe adhesion wear.While,due to the introduction of TiC enhancement phase,the composite is effectively resistant to abrasive wear.And CaF₂ forms into the lubricating film,reduces the shear strength and friction coefficient between the friction pairs,and inhibits the occurrence of adhesive wear.With the increase of CaF₂ content,the wear-resisting properties of composites is improved.However,the high content of CaF₂ can produce some aggregation in the material microstructure,affecting the homogeneity and mechanical properties of the materials.Therefore,the content of CaF₂ self lubricating phase should be proper.Namely,select Incone1718-12Ti-10 nickel coated graphite-30 nickel coated calcium fluoride?wt.%?powders blend as raw material,the composite will have the best high temperature wear resistant properties and can be used in high temperature and strong wear condition under high contact stress.