Effects of current density and agitation on co-deposition behaviour of electrodeposited Ni–TiO 2 composite coating

Abstract

In the present study, the effects of current density and agitation on the behaviour of co-deposition of TiO₂ particles in an electrodeposited nickel were investigated. The electrodeposited Ni–TiO₂ composite was manufactured from a nickel sulfamate bath containing TiO₂ particles. The volume fraction of the incorporated TiO₂ particles, the current efficiency (C.E.) and the hardness were measured in different current densities, magnetic bar speed and flow rate of the air bubble. The results indicate that the volume fraction of TiO₂ particles in the nickel matrix increased with a decrease of the C.E. at the mass transfer region, but the opposite tendency was observed under the charge transfer region. The hardness of the Ni–TiO₂ composite increased normally with an increase in the volume fraction of the TiO₂ particles. However, the hardness increased with a decrease in the volume fraction at a lower current density region owing to the hardening of the nickel matrix.