Effect of the current density on morphology, porosity, and tribological properties of electrodeposited nickel on copper

In the steel industry, nickel coating on copper has increased the lifespan of continuous ingot casting molds. The objective of this work is to estimate the porosity of nanocrystalline nickel electrodeposited onto copper. Characteristics of nickel coating such as hardness, wear resistance, porosity, morphology, and adhesion are very important for maximum performance of molds. The effective porosity in nickel coating was determined by using anodic voltammetry. The porosity of electrodeposited nickel onto copper increased from 0.16% up to 6.22% as the current density increased from 1.5 up to 8.0 A dm(-2). The morphology of the nickel electrodeposited at lower current densities was more compact. Tribological properties were studied using hardness measurements, and calotest. Results of calotest indicated a wear coefficient of 10(-6) for all samples. An extremely low friction coefficient of 0.06-0.08 was obtained for the sample deposited with a current density of 1.5 A dm(-2), and a friction coefficient of 0.15-0.21 was measured for the nickel coating electrodeposited at a current density of 5 A dm(-2). Effects of the current density of the electrodeposition process on the morphology, porosity, and tribological properties were evaluated.