Residual stresses of Ni alloy electrodeposits containing low levels of Fe, P, and B

Abstract

The effects of process parameters including the alloying elements, additive, pH, temperature and current types on the residual stresses of Ni alloys electrodeposited from a Ni sulfamate bath were investigated using a method involving a flexible bent strip. From the results, it was believed that the residual stresses of the Ni alloy deposits initially depended on a hydride then the alloying elements with increasing levels of those concentrations in the solutions. As the pH of the electrolytes changed from 1 to 3.5, the residual stresses in the deposits varied directly and intensively with the concentration of the NH4 in the solution. By increasing the temperature of the electrolytes from 50 °C to 70 °C, the tensile stresses in the deposits were decreased by the lower hydride that resulted from the decline in the hydrogen evolution reaction. The measured stress values with the current types showed a decrease in the order of the direct current, the pulse current (PC) and the periodic reverse current (PRC). The compactness of the deposit produced by the PC and the increased oxide and decreased hydride during the reverse pulse current of the PRC appeared to degenerate the tensile stresses.