Microstructure and Wear Response of Ni/SiC Laser Cladding Composite Coatings on a Carbon Steel

Abstract

The high-energy laser melts the cladding materials which coagulate onto the surface of the base materials. The laser cladding coatings are produced mainly in two methods: powder feeding and prefabricating. The grain-strengthening composite coatings could be formed more easily by prefabricating method than by powder feeding method. In this paper, Ni/SiC ceramic composite coating on carbon steel (45 steel) was made by prefabricating method. The microstructure and wear-resistance of Ni/SiC cladding coating on the 45 steel were studied using scanning electronic microscope (SEM) and wear test. The results showed that the microstructure of cladding coatings included bonding layer, thermo-affected layer and heat-affected layer after laser cladding. The microstructure of cladding coating was mainly of dendrite and cell-like crystals. The resultant multilayered coating had excellent adherence with the base steel. The addition of SiC particles into cladding coatings significantly reinforced the microhardness of laser cladding coating. Compared with Ni60A cladding coating, Ni60A/SiC cladding coating had high microhardness, which was attributed to not only the dispersion intensification effect of the SiC particle, but also by the new complicated phases. During laser cladding process, SiC particles may decompose and dissolve into the coating and result in solid solution strengthening effect which increases the microhardness of the composite coatings. The base material and Ni-based laser cladding coatings with and without SiC were tested to assess the wear-resistance property. The test results demonstrated that the laser cladding coatings had better wear resistance than the base material. Furthermore, the laser cladding coating with SiC particles had higher wear-resistance than the coating without SiC.