Corrosion resistance and mechanical properties of electrodeposited Co-W/ZrO2 composite coatings

Co-W/ZrO2 composite coatings were prepared on copper substrate by electrodeposition technology, and the effect of the concentration of ZrO2 particles in the plating solution on the content of ZrO2 particles in the composite coating, the corrosion resistance, and mechanical properties of the composite coating were studied. The results show that as the concentration of ZrO2 particles in the plating solution increases from 3 g/L to 26 g/ L, the content of ZrO2 particles in the composite coating first increases and then decreases, and the grains shape and compactness of the composite coating change significantly, resulting in differences in the corrosion re-sistance, hardness, wear resistance and tensile strength. Appropriate amount of ZrO2 particles in the plating solution can increase the content of ZrO2 particles in the composite coating, which may cause a greater degree of lattice distortion and dislocation leading to compact surface morphology and better mechanical properties. The composite coating prepared when the concentration of ZrO2 particles in the plating solution is 18 g/L is com-posed of face-centered cubic structure Co, close-packed hexagonal structure Co and Co3W phases with 7.35% ZrO2 particles. The composite coating has many densely arranged elongated structures, and exhibits the best corrosion resistance and mechanical performance with charge transfer resistance of 7056 omega center dot cm2, low-frequency impedance of 6960 omega center dot cm2 and phase angle of 66.5 degrees, hardness of 573.2 HV0.05 and tensile strength of 206.8 MPa, which are all higher than Co-W alloy coating.