Enhancement the Properties of Ni Compisite ...

Nickel electroplating is one of the few surface finishing processes that can satisfy the requirements of decorative and functional applications. In this work, nickel composite coatings containing nano–Cr2O3 particles were produced by conventional electroplating (CEP) technique from nickel-Watt’s type bath. Nano-Cr2O3 powders were synthesized by sol-gel technique. The influence of plating parameters including current density, pH, stirring rate, temperature and nano-Cr2O3 concentrations in the plating solution on the volume fraction (Vf %) of the co-deposited Cr2O3 particles in Ni-matrix was investigated. The results demonstrated that the Vf % of Cr2O3 particles incorporation in the deposited layer depends on these operating conditions. The maximum value of co-deposited nano- Cr2O3 can be achieved at optimum conditions; 20 g1-1 of Cr2O3 particles in suspension, 7Adm-2, pH 5, a stirring rate 150 rpm and 50 °C. The morphology of composite coatings was investigated using scanning electron microscopy (SEM). The results showed that the incorporation of nano-Cr2O3 particles changed the surface morphology of nickel matrix. The properties of the composite such as hardness and corrosion resistance were examined compared with steel uncoated and coated with nickel. The results revealed that the presence of nano-Cr2O3 particles in Ni-matrix greatly improved the hardness and corrosion resistance of steel.