Research Of Laser Cladding Ni45-TiB₂Composite Materials On Pure Copper

In this paper, a kind of ceramic reinforced metal matrix composite coating on the purecopper was fabricated by laser cladding technology, in which Ni45self-fluxing alloypowders were the cladding material and TiB2ceramic particles were as the reinforcingphases. Microstructure of the laser cladding coatings, the morphology and distribution ofTiB2particles, and the performance of composite coatings with different TiB2contentwere studied by means of X-ray diffraction analyzer (XRD), scanning electron microscopy(SEM), and transmission electron microscopy (TEM). In addition, the wear resistance ofthe composite coatings was analyzed preliminarily under the conditions of different loadand sliding velocity.By comparing the apparent morphology, interfacial bonding, dilution ratio,conductivity, tensile strength and micro-hardness of composite coatings prepared underdifferent technological parameters, the optimal parameters were determined as follows, thepower was1200W and the scanning speed was3mm/s.The research was focused on the microstructure of TiB2/Ni45composite coating. Theresults of XRD showed that main phases in the coating were (Ni, Cu), TiB2, CrB and otherintermetallic compounds. Dendrites and the fine interdendritic organizations were thetypical structure of composite coating. There were three different states for TiB2in thecoating: regular grains formed by the laser heat shock, partially melted grains with smoothsurface and unmelted larger particles, et al. The interfaces between TiB2and (Ni, Cu) solidsolution were analyzed by TEM. It found that three different states of TiB2had goodinterfacial bonding with the matrix. Therefore, it was feasible to add TiB2into the claddingcoatings as the reinforced phase.The performance for various composite coatings with different content of TiB2wasstudied. With the increase of TiB2content, conductivity, tensile strength and micro-hardness of cladding coatings were all increased. This showed that the composite coatingsindeed improved the hardness of copper matrix, meanwhile, TiB2also played a role inenhancing coating matrix.In addition, the tribological behaviors of TiB2/Ni45composite coatings under different load and sliding velocity at room temperature were studied. The results indicated that boththe load and speed had effect on the abrasion resistance, and the main mechanism wasabrasive wear. TiB2acted a role of antifriction lubricating in coatings. Meanwhile, thewear resistance of the composite coatings was improved significantly when the TiB2content increased.