Study On The Technology And Mchanical Properties Of Ni60B-WC/Co Composite Coating Prepared By Cr12-based Laser Cladding

Wear and fatigue are the most common surface failure mechanisms when mold parts work in harsh environments.Since most of these failures begin at the surface,it is possible to use remanufacturing technology to repair the surface of parts without affecting the surface performance of the part,thereby reducing the cost of the enterprise.Compared with other surface remanufacturing methods,laser cladding technology has the advantages of low dilution rate,fast solidification rate,and the like,and can deposit a coating material with controllable thickness on a selected substrate.In this paper,a multi-factor multi-level multi-objective visual design（m³VD）method was used to design the experimental scheme,and a Ni60B-WC/Co composite coating was prepared by a laser cladding process.The microstructure and phase composition of the composite coatings were analyzed using advanced material characterization techniques（SEM/EDS,XRD）.The microhardness and wear properties of the coatings were tested using a microhardness tester and a friction and wear tester,respectively.And visual analysis of the test results showed that:（1）The microstructure of the coating is dense and forms a good metallurgical bond with the metal matrix;the main phase of the coating isγ-（Ni,Fe）solid solution and a small amount of unmelted WC particles,and also contains trace amounts of Cr₂₃C₆,Cr₇C₃,Co₃W₃C,and other dispersion phase;The dendritic structure is mainly composed of Ni-based solid solution.The interdendritic structure is a eutectic structure composed of carbides formed of Co,Cr,W and other elements and a Ni-based solid solution.（2）The laser power,scanning speed,lapping rate,WC content and cobalt content were selected as the influencing factors.The experiment was arranged by multi-factor multi-level multi-objective visual design method（m³VD）.The micro-hardness,friction coefficient and wear amount of the coating were used as the test indexes.The relationship between the experimental factors and the indicators was analyzed by the multi-factor multi-level visual analysis（m³VA）method.The optimum process range was obtained:the laser power was 1800W²000W.The scanning speed is 6mm/s⁷mm/s,the overlap rate is 35%⁴0%,the WC content is 35%⁴0%,and the Co content is 10%¹2%.In this case,the microhardness,wear and friction coefficient of the coating can be optimized theoretically.（3）Coatings prepared using the process parameters within the optimized range have a 3 to 4 times higher microhardness compared to the original matrix,and the amount of wear and the average coefficient of friction are greatly reduced.