**2.2. pH of the bath**

The effect of pH on particle incorporation is dependent on the nature of the particles. For instance, when MoS2 particles are used as the incorporate particles, the effect of pH value on the particle content in deposit was insignificant. Nevertheless it can be concluded that increasing pH decreased the amount of particles present in the coating [6]. However, incor‐ porated particles are significantly decreased when pH is below 2 in Al2O3-Ni coating pair [11]. In addition, decreasing pH is preferred to manage the internal stress. Low pH values, less than 5, are selected to obtain acceptable stress levels [10]. Increase in pH of the solution may lead to discharge of hydroxyl ions instead of nickel dissolution and oxygen evolution [10] resulted in high internal stresses. It is also concluded that the internal stress was increased when the pH was increased from 2 to 4 in MoS2 – Ni system [12].
