Study On Microstructure And Properties Of Laser Cladding In-situ Composite Carbides Reinforced Nickel Matrix

With laser cladding technology to improve the hardness and wear resistance of the surface of mechanical parts as the goal,by preparing composite carbides to enhance the performance of the nickel-based surface coating,explore the influence of process parameters and the proportion of elements in the in-situ synthesis system on the microstructure and macroscopic properties of the cladding layer,analyze the reaction mechanism of the in-situ synthesis of composite carbides,and study the microstructure and change mechanism of materials through the first principle,And then explain the change rule of material macroscopic properties.The research results provide technical support and theoretical basis for the research of laser cladding surface strengthening.First of all,the problem of in-situ synthesis of single carbide by laser cladding was studied,and the Ti C hard phase reinforced nickel-based composite coating was prepared.The effects of laser power,scanning speed,and molar ratio of carbon to titanium on the hardness of the cladding layer,the amount of in-situ synthesis and the cladding efficiency were studied,and the mechanism of the effect of the coupling of process parameters and the element ratio in the in-situ synthesis system on the performance of the cladding layer was explored.With the help of sensitivity analysis,further clarify the sensitivity parameters under the corresponding output,reveal the formation mechanism of in-situ synthesized single carbide and the change mechanism of grain morphology,and determine the optimal process parameters for subsequent research.Secondly,the first principle based on the density functional theory is used to calculate the microscopic lattice properties of composite carbides,and the influence of the introduction of the second element on the lattice parameters,formation energy,elastic modulus and crystal structure of the composite carbides at different ratios is explored,so as to obtain the optimal composite carbide elements,and further explore the various properties of the selected composite carbides,In order to clarify the internal law of the mechanical property change of the composite carbide,it provides a theoretical basis for the preparation of high-performance coatings by laser cladding.Finally,the in-situ(Ti,V)C composite carbide reinforced cladding layer was prepared by laser cladding technology,and the macroscopic morphology,mechanical properties,microstructure and element distribution of the composite carbide under different powder ratios were investigated.The comprehensive evaluation is made from the interface morphology,phase composition,microstructure and mechanical properties,and the evolution process of the molten pool and the coating strengthening mechanism are analyzed,so as to obtain the best powder ratio,and finally realize the preparation of composite carbide strengthened nickel-based coating,and realize the surface strengthening of the parts.The research results provide a theoretical basis for the performance control of the coating prepared by laser cladding composite carbide based on the first-principles calculation,and provide technical support for the surface strengthening of parts in the environment of high hardness requirements,high cycle times,high friction and wear.