Investigation of the Cauliflower Morphology Formation in the Ni–TiO2 Coating Produced by the Rotating Cathode Method

Abstract

Ni—TiO₂ composite films were electrodeposited from a nickel-plating bath containing various amounts of TiO₂ particulates of different particle sizes. The films deposited from a bath that contained 10 g/L TiO₂ did not contain any TiO₂. On the other hand, all films deposited from a bath with 40 g/L TiO₂ contained some TiO₂. Current density and cathode rotation speed did not seem to have much effect on the incorporation of TiO₂ in the nickel matrix film, but the amount of TiO₂ powder in the bath and also their particle size appeared to be very influential parameters in the incorporation of TiO₂ particulates. The Ni–TiO₂ composite films showed some “cauliflower-type” globular grains, which were compact without any cracks or pits. They were smaller for the films deposited from a bath containing small particle-size TiO₂ particles. Using Monte Carlo simulation, it can be concluded that in the Ni–TiO₂ composite coating, nickel atoms are first deposited on the TiO₂ particulates and then a Ni–TiO₂ colony will be formed on the surface of the substrate and the final structure of cauliflower was created.