Microstructure And Property Research Of Ni60A-Cr₂O₃ Coating Prepared By Supersonic Plasma Spraying

The research on the properties of Ni based alloy coating has been studied by adding ceramic materials,such as carbides,oxides,and so on,this type of compo site coating has the advantages of high hardness and toughness of the nickel matrix,which has two advantages.In this paper,the microstructure and properties of Ni60A-Cr₂O₃ composite coating and Ni60A coating were analyzed,and the effect of adding different content Cr₂O₃ on the properties of Ni60A coating was investigated.By XRD analysis,it was known that the composition of the composite coating was different from that of the Ni60A coating,but the phase structure of the coatings with different Cr₂O₃ content was basically the same.According to the SEM scanning images,it was known that the middle layer structure of the composite coating is obvious,and the Cr₂O₃ phase is tightly coated by the Ni60A matrix.The combination of coating and substrate was mainly mechanical bonding.The hardness test results showed that the Rockwell hardness of the composite coating was larger than that of the Ni60A coating after the addition of Cr 2O3,with the increase of Cr₂O₃,The Rockwell hardness of the coating increased f irst and then decreased,and the maximum hardness of the coating was 35% Cr 2O3 ?The microhardness of the composite coating was larger than that of Ni60A,When the Cr₂O₃ volume fraction was 25%-45%,the microhardness of the composite coating had little difference.The wear resistance of the composite coating was lower than that of the Ni60A coating after the addition of Cr₂O₃,When the volume fraction of Cr₂O₃ was 35%,the wear rate of the composite coating was the least,and the wear rate of the composite coating was reduced by 5 times compared with that of the Ni60A coating,which indicated that the wear resistance of the coating was enhanced by the addition of Cr₂O₃,Based on the analysis of wear morphology,the wear resistance of Ni60A coating was mainly adhesive wear,and the wear resistance of composite coating was mainly abrasive wear.Porosity measurements showed that the coating porosity formed by supersonic plasma spraying was low.The porosity of the composite coating was more than that of the Ni60A coating,and the porosity of the composite coating increased with the increase of Cr₂O₃ content.Combined with the hardness and wear resistance of the coating,it has less influence when the porosity wan controlledin 4.7%.The results showed that the corrosion rate of the composite coating was faster than that of the Ni60A coating,and the corrosion resistance of the composite coating in HCl solution and H2SO4 solution was not as good as that of the Ni60A coating.The electrochemical tests showed that both th e composite coating and Ni60A coating were passivated in H2SO4 solution,and Cl-could accelerate the corrosion rate of the coating in Na Cl solution.Through the comparison and analysis of various experiments,it can be seen that Cr₂O₃ can enhance the wear resistance of Ni60A coating,and the wear resistance of the composite coating was the best when the Cr 2O3 volume fraction was 35%.The Ni60A+35%Cr₂O₃ composite coating formed on the substrate surface can be used under the working condition of high wear re sistance,and has a good application prospect.