Microstructure and Properties of ZrB₂-SiC Reinforced Copper Matrix Composite Coatings Prepared by Laser Cladding

With the use of electrolytic Cu powder, Zr powder, Si powder and nickel-coated B₄C powder as cladding powders, in-situ synthesized ZrB₂-SiC reinforced copper matrix composite coatings were prepared by laser cladding on the surface of the copper substrate to improve the surface hardness and wear resistance. Under the condition of a laser energy density at 60 kJ/cm², the macroscopic surface of the composite coating was continuously flat. The microstructure and phase of the cladding coating were analyzed by means of XRD and SEM. The reinforcements with nano-scale particle and micron-scale needle-like structures were in-situ synthesized in the cladding coating, and the content of the reinforcement phase decreased slightly from the coating surface to the substrate. The phase analysis results showed that the reinforcements included ZrB₂ and SiC. When the content of the reinforcement was increased to 30 wt%, microhardness also increased from 48 HV_0.2 to 309 HV_0.2, which was about 5.6 times that of the copper matrix. The wear resistance of the composite coatings was characterized by current-carrying wear tests. By keeping the sliding speed and load constant, the wear rate decreased with an increase in the reinforcement content, and the wear mechanism changed from adhesive wear to abrasive wear. The wear rate of the composite coating with the current was higher than that without the current due to its electric ablation and high temperature.