Preparation Process And Properties Of Ni-Cr-Co Alloy High Temperature Wear Resistant Coatings

High temperature friction and wear is one of the worst forms of failure in the working environment of mechanical motion..According to statistics,in various engineering fields of industrial production,mechanical failure due to high temperature friction and wear accounts for 60%-80%of total part failure;energy loss due to friction and wear reaches 30%of total energy consumption-50%.Therefore,the main research direction at present is to prepare a protective coating with high temperature friction and wear resistance on the surface of high temperature parts,in order to increase the service life of high temperature parts.This paper mainly uses laser cladding rapid prototyping technology,nickel chrome cobalt superalloy original powder,nickel chrome cobalt superalloy original powder+20%molybdenum powder(wt.07%),nickel chrome cobalt superalloy original powder+22.5%molybdenum powder(Wt.%),nickel-chromium-cobalt superalloy original powder+22%molybdenum powder+8%titanium iron powder(wt.%)four mixed powders to prepare a cladding layer.The microstructure of the coatings of each group was analyzed by metallographic microscope,X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The solidification mechanism of laser cladding rapid prototyping was studied.It is found that the composition phase of the original powder cladding layer of Ni-Cr-Co superalloy is y-(Ni,Fe)solid solution,and the composition phase of the other three groups of cladding layer is y-(Ni,Fe)solid solution,MoSi2 and other solid solution phases.The solidification tissue growth morphology is mainly determined by the solid-liquid interface stability factor G/R(G is the temperature gradient and R is the solidification rate).The composite cladding layer is fine and dense,and there are no obvious cracks and holes in the macroscopic.The average microhardness of the four composite cladding layers was tested by microhardness tester.The results show that the wear resistance phase MOSi2 increase the microhardness of the cladding layer with the increase of molybdenum powder content.With the increase in titanium content,the microhardness of the pattern is slightly reduced.Four sets of composite coatings prepared by laser cladding were tested by CFW-1M rotary PC control coating friction and wear tester at room temperature and 600? dry sliding friction and wear test according to the wear of the cladding layers of each group.The relative wear resistance was calculated by weight loss,and the wear profile was observed by the super depth of field three-dimensional shape analyzer.Scanning electron microscopy(SEM)and energy spectrum(EDS)analysis were performed on the wear scar.The results show that in high temperature wear,the main adhesive wear is accompanied by certain oxidation and plastic deformation.The wear resistance of the original powder cladding layer of Ni-Cr-Co superalloy is the worst,due to the reinforcement phase MOSi2 in the composite.Considering the microhardness of the cladding layer,the weight loss of the grinding,the friction coefficient,the relative wear resistance and the wear scar morphology,that is,the nickel-chromium-cobalt superalloy original powder+20%molybdenum powder(wt.%),nickel-chromium cobalt high temperature The alloy raw powder+22.5%molybdenum powder(wt.%)is used as the material.The cladding layer prepared by laser cladding rapid prototyping technology has good high temperature wear resistance,and the thermal shock resistance and hardness coexist,and can be used for high temperature.Protective coating for working parts in the environment.