| Remanufacturing is a method of repairing damage or scrap parts by using of advanced manufacturing technology.Thermal spraying technology is a kind of remanufacturing technology,This technology has been widely applied to industrial fields.This paper takes the large centrifugal compressor impeller rotor material FV520B martensitic stainless steel as the research object.In view of the impeller rotor wear problem,Cr3C2-NiCr/NiCrAl composite coating is chosen to be repairing layer,and the plasma arc remelting is carried out in order to improve the coating quality and mechanical properties.The repair layer has good combination with matrix,it has excellent wear-resisting corrosion resistance and has been used on the easy wear parts,can fully meet the shape and properties recovery of the impeller rotor sexual,performance and service life of remanufacturing components is better than that of the new components,which has important research significance.In this paper,the plasma spraying technology is used to prepare the NiCrAl bonding layer on the matrix,and supersonic flame spraying technology is used to prepare Cr3C2-NiCr function layer on the basis of bonding layer.This paper introduces the substrate pretreatment,spraying trajectory control,coating thickness control and spraying process parameters selection,and the composite coating microstructure,phase composition and mechanical properties are tested and analyzed.Plasma arc remelting technology is carried out on the composite coating surface,and three factors,four levels orthogonal test is designed,selecting the remelting power,remelting distance,spray gun moving speed three process parameters as factors,to remelting process parameters are optimized based on bonding strength indicator.The optimum technological parameters are obtained by using the comprehensive balance method and taking coating hardness and porosity as indicators.By single factor test,the microstructure and composition of Cr3C2-NiCr/NiCrAl coating are analyzed,and the influence of remelting power on the microstructure and composition of the coating was investigated.The effects of the remelting power on the microstructure and the diffusion of the interface elements are studied by analyzing the interface characteristics and energy spectrum of the Cr3C2-NiCr/NiCrAl coating.Through the friction and wear test,the friction factor curves of different power remelting coatings and the surface morphology of the abrasion surface are analyzed and compared,and the parameters of the remelting process are investigated.The test results show that the three factors in the remelting experiment effects on tensile bond strength of coating:remelting power shift speed>gun remelting distance>tensile bond strength,the optimum technological parameters:40kw for remelting power,0.4m/min for spray gun moving speed,60mm for remelting distance.The optimized process parameters are optimized by comprehensive equilibrium method,The optimum technological parameters are determined by the comprehensive balance of the two indexes:40KW for remelting power,0.4m/min for spray gun moving speed,and 60mm for remelting distance.Within a certain range,with the improvement of remelting power,density of function layer increases,the functional layer and bonding layer combine more closely,porosity and crack decrease near the interface,the boundary between layer and layer is blurred,elements thermal diffusion phenomenon enhances near the interface,microzone metallurgical combination appears at the interface,the combination of the coating performance improves.When remelting power is too large,longitudinal growth crack forms in the functional coating which is detrimental to the performance,oxidation phenomenon of the coating is serious,the combination of bonding layer and matrix deteriorates,which has bad effects on the performance of the coating combination.Friction and wear test results show that within the 30kw-42kw,friction and wear properties of the coating enhances unceasingly with the improvement of remelting power,surface wear of 42kw remelting coating is minimum,friction and wear performance achieve the best;The surface of the 45KW remelting coating has pits,delamination and peeling,the friction and wear properties of the coating deteriorate. |
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