Comparative study on the effect of current density on Ni and Ni–Al2O3 nanocomposite coatings produced by electrolytic deposition

Abstract

Nickel was deposited galvanostatically at 0·23, 0·77, 1·55, 3·1 and 5·4 A dm−2 current densities at room temperature. An XRD technique was employed for evaluating the grain size and preferred orientation of the nickel deposit. The cross-sections of the nickel deposits were subjected to microhardness and microstructure analysis. Nanosize alumina was prepared by a solution combustion technique, and the powder was characterised by XRD and particle size analysis. The particle size of Al2O3 powder synthesised by the combustion process was 30 nm. XRD confirmed the presence of pure α-Al2O3. Combustion synthesised alumina (CSA) powder was codeposited in the nickel matrix at various current densities, as in the case of nickel. Similarly, commercially available 0·05 μm Al2O3 containing a mixture of α and β phases was codeposited in nickel matrix. The Ni–Al2O3 nanocomposite coatings were characterised by XRD, microhardness measurement and image analysis. The results obtained with nickel and Ni–Al2O3 composite coatings are compared.