Comparative study on the effect of current density on Ni and Ni-Al2O3 nanocomposite coatings produced by electrolytic deposition13;

Nickel was deposited galvanostatically at amp; middot;23, 0amp;middot;77, 1amp;middot;55, 3amp;middot;1 and 5amp;middot;4 A dmlt;supgt;-2lt;/supgt; 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 Allt;subgt;2lt;/subgt;Olt;subgt;3lt;/subgt; powder synthesised by the combustion process was 30 nm. XRD confirmed the presence of pure amp;alpha;-Allt;subgt;2lt;/subgt;Olt;subgt;3lt;/subgt;. Combustion synthesised alumina (CSA) powder was codeposited in the nickel matrix at various current densities, as in the case of nickel. Similarly, commercially available 0amp;middot;05 amp;mu;m Allt;subgt;2lt;/subgt;Olt;subgt;3lt;/subgt; containing a mixture of amp;alpha; and amp;gamma; phases was codeposited in nickel matrix. The Ni-Allt;subgt;2lt;/subgt;Olt;subgt;3lt;/subgt; nanocomposite coatings were characterised by XRD, microhardness measurement and image analysis. The results obtained with nickel and Ni-Allt;subgt;2lt;/subgt;Olt;subgt;3lt;/subgt; composite coatings are compare