Study on the Microstructure and Properties of Al₂O₃ Reinforced Ni-Co Based Composite Coating

Enhancing the anti-friction and anti-wear and corrosion resistant properties of mold copper plates holds significant research significance and value for the development and improvement of continuous casting molds.In this study， a Ni-Co/Al2O3 nanocomposite coating was electrodeposited on the surface of a Cu-Cr-Zr alloy substrate with the assistance of ultrasonic during the electroplating process， and the plating bath was formulated by incorporating nano-Al2O3 particles with an average diameter of 20 nm into a sulfamate-based electrolyte system.Subsequently， the composite coating was systematically characterized through friction and wear testing， high-temperature oxidation evaluation，microhardness measurement， adhesion assessment， and corrosion resistance analysis.Results showed that the optimal process parameters were current density of 5 A/dm2， bath temperature of 50 ℃， nano-Al2O3 concentration of 10 g/L， deposition time of 1.00 h， ultrasonic power of 200 W， and mechanical stirring at 500 r/min.Under this process，the Ni-Co/Al2O3 nanocomposite coating exhibited the highest surface microhardness， the finest and most compact structure arrangement， the uniformly dispersed nanoparticles embedded in the metal matrix without obvious agglomeration， and the optimal microscopic morphology.Moreover， the Ni-Co/Al2O3 nanocomposite coating prepared with ultrasonic assistance had excellent high-temperature oxidation resistance at 400 ℃； Compared with Cu-Cr-Zr alloy and Ni-Co alloy coatings， Ni-Co/Al2O3 nanocomposite coating possessed the best anti-friction and anti-wear performance and corrosion resistance