In order to improve the comprehensive performance of the electrodeposited Ni-P composite coating on the cylinder liner surface of the robot arm, ZrO2 was doped into the Ni-P coating through the electrodeposition process, and the structure, wettability, hardness and electrochemical corrosion performance of the Ni-P-xZrO2 nano-composite coating were studied. Results showed that the intensity of ZrO2 diffraction peak at 8.94° increased continuously with the gradual increase of ZrO2 content in the electrolyte solution. After the calcination of the coating, Ni and Ni3P phase components were precipitated, and ZrO2 was doped into the Ni-P coating. When higher content of ZrO2 was added to the electrodeposition solution, the coating formed a rougher surface and produced more dendrites, and the coating changed from hydrophilic to hydrophobic. After increasing the ZrO2 content within a certain range, the Ni-P-ZrO2 composite coating with higher hardness was obtained, and the maximum hardness of the composite coating was close to 1 110 kg/mm2 when the ZrO2 concentration was 5 g/L. A large number of grain boundaries were formed during the precipitation of hard phase Ni3P, resulting in a large number of dislocation accumulation in the grain boundary area, leading to strain hardening. The corrosion current density decreased first and then increased with the increase of ZrO2 content, and the minimum value was obtained at 5 g/L, whereas the changing law of corrosion voltage was opposite.
