Sediment Co-Deposition of Nanostructured Ni-Al2O3 Composite Coatings
Nanostructured Ni-Al2O3 composite coatings incorporated with various contents of α-Al2O3 nano-particles were prepared on mild steel by using novel sediment co-deposition (SCD) technique. For the comparison reason, the pure Nickel coating and the Ni-Al2O3 composite coatings were fabricated by means of conventional electroplating (CEP) technique. The electroplating was carried out in Watt’s bath without any additives except for nano-α-Al2O3 suspension. The influence of the nano-particulates concentration, current density, and the mode of electroplating on the composite coatings were investigated. The results reveal that the weight percent of nano-Al2O3 increases with increasing nano-α-Al2O3 concentration in plating bath and some agglomeration occurs on the surface of composite coatings. The current density affects the alumina content in the composite coatings as well. The nano-α-Al2O3 incorporation by the SCD technique is higher than that of the CEP technique. The microhardness increases, while the wear rate decreases with increasing content of the nano-Al2O3 in the composite coatings. The incorporation of nano-α-Al2O3 particles changes the surface morphology of Ni matrix and modifies the texture of composite coating to exhibit a preferentially (111) growth orientation. Moreover, the co-deposited nano-sized α-Al2O3 particles are uniformly distributed in the Ni matrix and contributed to remarkably increase the microhardness, and tribological properties of the Ni base coating.
M.K. Lei, X.P. Zhu, K.W. Xu and B.S. Xu
Q. Y. Feng, T. J. Li, H. Y. Yue, F. D. Bai, K. Qi, J. Z. Jin, "Sediment Co-Deposition of Nanostructured Ni-Al2O3 Composite Coatings", Key Engineering Materials, Vols. 373-374, pp. 244-247, 2008