Study On Properties Of NiMoCrFeCo-WC Alloy Powder And Its HVOF Coating

The purpose of this paper is to discuss the preparation of NiMoCrFeCo-WC alloy powder and the properties of supersonic flame spraying coating.On this basis,the differences in properties of different WC coatings and the matching properties of steel matrix materials and WC coatings are studied and compared.NiMoCrFeCo-WC powders with 18%,24%and 30%binder phase content were prepared by spray drying and sintering method.The microscopic characteristics and particle structure of the powders were observed and analyzed by SEM.The phase and particle size distribution of the powders were analyzed by XRD and particle size analyzer,so as to explore the effect of binder phase content on the preparation of NiMoCrFeCo-WC powders.NiMoCrFeCo-70WC,NiMoCrFeCo-76WC,NiMoCrFeCo-82WC,10Co-4Cr-WC and Co12-WC coatings were prepared by HVOF spraying.The effects of NiMoCrFeCo binder content on the microstructure and mechanical properties of WC coatings were studied,and the performance differences of NiMoCrFeCo-82WC,10Co-4Cr-WC and Co12-WC coatings with different binder phases were discussed.The microhardness,fracture toughness and interfacial bonding properties of NiMoCrFeCo-82WC coatings on 9Cr8Mo V,Cr12Mo V,17-4PH,9V powder steel and420V powder steel matrix materials were compared and studied.The effects of matrix materials on the properties of NiMoCrFeCo-82WC coatings were analyzed.The results show that:NiMoCrFeCo-WC powder particles are spherical or nearly spherical,and the powder particles are rough and porous.With the decrease of NiMoCrFeCo binder phase content,the particle size distribution of the powder is more concentrated and the particle size is more uniform.Powder particle structure is a porous powder particle body which is formed by wrapping multiple WC particles in metal binder phase and bridging numerous wrapping particles.The wear performance of the WC coating shows that the wear rate of the WC coating is consistent with the hardness of the coating when the load is low.The microhardnessoftheNiMoCrFeCo-70WC,NiMoCrFeCo-76WC,NiMoCrFeCo-82WC,10Co-4Cr-WC and Co12-WC coatings are 1150.6HV,1152.9HV,1177.9HV,1332.2HV and 1375.2HV,respectively.The corresponding wear weight loss of five WC coatings under 200N loading is 7.6mg,4.5mg,3.8mg,3.5mg and 2.1mg,respectively.The fracture toughness of the coatings is 53.8k N·m^-3/2,59.6 k N·m^-3/2,96.3 k N·m^-3/2,100.6 k N·m^-3/2 and 92.2 k N·m^-3/2,respectively.The wear mechanism of WC coating is adhesive wear and abrasive wear.When the coating hardness is low,the wear mechanism is mainly adhesive wear,and when the coating hardness is high,the wear mechanism is mainly abrasive wear.The wear mechanism of the WC coating is slightly different when the load is increased.In the corrosion test,the WC coating shows good corrosion resistance,along with the increase in NiMoCrFeCo content of binding phase,NiMoCrFeCo-WC coating shows more excellent corrosion resistance,10Co-Cr-WC and Co12-WC coating corrosion rate is lower than NiMoCrFeCo-82WC coating corrosion rate.The corrosion mechanism of WC coating is mainly chemical corrosion and galvanic corrosion.The NiMoCrFeCo-82WC coatings are closely bonded to the substrate materials of 9Cr8Mo V,Cr12Mo V,17-4PH,9V powder steel and 420V powder steel,but the bearing capacity of the NiMoCrFeCo-82WC coatings on the five substrate materials is different.The NiMoCrFeCo-82WC coatings on 9Cr8Mo V,9V powder steel and420V powder steel matrix materials have good bearing capacity;The NiMoCrFeCo-82WC coatings on Cr12Mo V and 17-4PH matrix materials have poor bearing capacity.There are 62 figures,17 tables and 85 references in this paper.