The co-deposition mechanism of TiO₂ and Ni was studied. The amount of TiO₂ particles in composite coating films increased linearly with the electrodeposition time and amount of Nickel deposited. Therefore, it was surmised that TiO₂ particles close to the cathode are entrapped by the reduction of Ni²⁺ ion to Ni.
TiO₂ particles that adsorb cationic surfactants have a positive charge. Therefore, this adsorption affects the concentrarion of TiO₂ particles close to the cathode and then the amount of co-deposited TiO₂.