Behaviour of Zn-SiO2 electrodeposition in the presence of N,N-dimethyldodecylamine

Zn-SiO2 composite electrodeposits have been produced from a sulphate bath. The effects of process parameters such as current density, agitation, particle loading and deposition time on the rate of particle incorporation are presented. It was shown that the amount of SiO2 embedded in the coating is dependent not only on the rate of agitation but also on the type of agitation. The effect of particle size was extensively investigated. It was found that the level (wt.%) of larger particles (2 pm) in the deposits was higher than that of smaller ones (20 nm) produced under similar experimental conditions. A study of the influence of N,N-dimethyidodecylamine (NND) as a surface-active additive is also presented. Cathodic polarisation studies show that addition of SiO2 to the bath increased the zinc deposition current densities whilst the presence of NND in the bath seemed to inhibit the rate of zinc deposition. However, it was established that the addition of N,N-dimethyldodecylamine significantly improved the rate of particle incorporation for larger particles. Morphological characteristics of Zn-SiO2 electrodeposits produced under various electrodeposition conditions are also presented. (c) 2005 Elsevier B.V. All rights reserved.