Ni-Co-TiO2 nanocomposite coating prepared by pulse and pulse reversal methods using acetate bath

Ni-Co/nano TiO2 (Ni-Co-TiO2) composite coatings were prepared under pulse current and pulse reverse current methods using acetate bath. The microstructure and corrosion resistance of the coatings were characterized by means of XRD, SEM and EIS. Both the Ni-Co alloy and composite coatings exhibited single phase of Ni matrix with face centered cubic (fcc) crystal structure. The crystal orientation of the Ni-Co-TiO2 composite coating was transformed from crystal face (2 0 0) to (1 1 1) compared with Ni-Co alloy coatings. The results showed that the microstructure and performances of the coatings were greatly affected by TiO2 content on the deposits prepared by PC and PRC methods. The microhardness and corrosion resistance were enhanced in the optimum percentage of TiO2 composite coatings. The PRC composite coatings were exhibited from compact surface, higher microhardness and good corrosion resistance compared with that of the PC composite coating. (C) 2010 Elsevier B. V. All rights reserved.