**3. Bath temperature**

The effect of the temperature on the particle content in the deposit depends on the type of the particle. There is a small increase in the particle (MoS2) content in coating with increasing the temperature 30, 40, 50 respectively [6]. It was mentioned that the temperature has an insignif‐ icant effect. For instance, no effect of temperature was detected in BaCr2O4-Ni [13] and Al2O3- Ni [14] coating couples. Because, the applied voltage is the main parameter that directly affects the activity of the reaction. In addition, Ni deposits more efficiently with increase in temper‐ ature. On the other hand, the influence of the temperature was reported as positive up to certain point. After that point, the amount of particles decreases with increasing the temperature.

General trend on the effect of the bath temperature on the internal stress is positive, meaning that increasing temperature decreases the internal stress. On the other hand, according to some of the studies the stress is more influenced by the current density regardless of the temperature [10].

Another advantage of the high temperature is the polarization effect. It is known that concen‐ tration polarization is the component of the polarization which is due to the change in the electrolyte concentration that stems from the current flow through the electrode – solution interface. So, the electrochemical cell potential difference deviates from its equilibrium value. Concentration polarization is decreased by increasing temperature because diffusion layer thickness gets smaller and ionic diffusion increases.

On the other hand, high temperature values increases energy consumption and supply heat for bath evaporation. Furthermore, thermal stresses will arrive at high processing tempera‐ tures and can become a serious problem especially when the coating and substrate have different thermal expansion coefficients. Therefore, an optimum plating temperature must be preferred to satisfy energy consumption and the coating quality.
