Study On Interfacial Coupling Mechanism And Microstructure And Properties Of Laser Cladding Nickel - Coated Boron Carbide

The Boron carbide is one of material that its hardness is only less than diamond and cubic boron nitride, B4C has high melting point, high hardness, high temperature resistance, corrosion resistance, wear resistance and so on. They are widely used in all kinds of wear-resistant and corrosion-resistant parts. However, because of the B4C’s thermal expansion coefficient and elastic modulus is difference to the parts, the cladding layer and the substrate combination can not be very good, and can not obtain a good microstructure coating. Therefore, preparation of the coated with nickel package of boron carbide powder to improve this problem. In this paper, the coating of boron carbide powder is studied and analyzed by laser cladding technology. The main work is as follows:A simplified theoretical model of coated metal on the surface of nonmetallic ceramics Boron carbide was established, choice Ni as the coating layer,and the mass fraction of coated metal was calculated, and the Ni package B4C powder was prepared;With the preparation of power, Ni package B4C and metal based (such as Fe, Co, Ni) Ni package B4C composite coating were experimented by laser cladding technology with different process parameters (such as laser power, scanning speed, overlap ratio and B4C mass percentage). SEM, EDS and XRD were used to investigate the microstructure, composition distribution and phase of the coatings. The influence of different process on microstructure and properties of coatings were investigated, and reveal the different process impact on the property of coating. The analysis results are as follows:microstructure of cladding layer is uniform and compact, the cladding layer and substrate are metallurgical bond; The hardness resistance are greatly improved compared with the matrix; When the lap ratio is 33%, the effect of multilayer cladding is better;The strengthening effect of B4C in metal matrix composites, the wear resistance of the cladding layer was detected, and the wear resistance of the cladding layer was found to increase by 5～10 times than that of the substrate, the composition and distribution of each phase in the cladding layer are analyzed, and analize the interfacial coupling mechanism of the strengthened phase in the microstructure:The coupling between the substrate and the cladding layer is mainly composed of the metallurgical bonding and the enhanced interphase interface;The coupling of the cladding layer is formed by the compound made by the interaction force between the intermolecular, the hard alloy phase, the solid solution, the eutectic compound and other Strengthening phase coupling.