Effects of pH and cobalt concentration on the properties of nickel cobalt alloy plating

Nickel-Cobalt alloys are among the most prominent materials due to their magnetic properties, wear resistance, thermal conductivity and electrocatalytic activities. Although nickel and/or nickel-cobalt alloys have been plated from Watts solution for a long time, today, especially for the engineering applications, nickel sulfamate based solutions are commonly preferred due to the advantages of low internal stress and high deposition rate. The properties of nickelcobalt alloy platings are directly related to the pH and the cobalt amount of the solution. In the literature, the optimum pH range was determined as 3.0-5.0, but the effects of the changes within this range on the properties of the coatings have not been investigated deeply. Three different solutions were prepared to perform coatings from solutions containing different pH and amounts of cobalt in this study. The coatings were characterized in terms of grain size and shape, composition, and hardness properties