Effect of Some Operating Variables on the Characteristics of Electrodeposited Ni-α-Al²O³and Ni-TiO²Composites

SUMMARYThe electrodeposition of Ni-α-Al2O3 and Ni-TiO2 composites was studied from baths containing 100 NiSO4.7H2O, 40 NiCl2. 6H2O,25 H3BO3 and Na2 SO4.10H2O with either 1–20 α-Al2O3 or 1–20 gl−1 TiO2 particles suspended in the bath. During electrodeposition, the cathodic polarization increased with increase of both the size and concentration of the inert particle in the bath. An explanation of the mechanism of codeposition of the inert particles with nickel has been presented. The current efficiency of nickel electrodeposition is relatively high (95%) and is not affected by inclusion of the inert particles. As revealed by scanning electron microscopy, the growth morphology of the nickel deposit is affected by the inert particle content, the deposition current density and pH of the bath. The microhardness of the nickel deposit (116 kgf mm−2) increased with increase of the inert particle content and increase of the deposition current density until it reached 243 kgf mm−2 as a maximum. The data obtained revealed that the microhardness of the deposit is a morphological-sensitive property.