Preparation and characterization of nickel nano-Al2O3 composite coatings by sediment co-deposition

Ni-Al2O3 composite coatings were prepared by using sediment co-deposition (SCD) technique and conventional electroplating (CEP) technique from Watt's type electrolyte without any additives. The microstructure, hardness, and wear resistance of resulting composites were investigated. The results show that the incorporation of nano-Al2O3 particles changes the surface morphology of nickel matrix. The preferential orientation is modified from (200) plane to (111) plane. The microhardness of Ni-Al2O3 composite coatings in the SCD technique are higher than that of the CEP technique and pure Ni coating and increase with the increasing of the nano-Al2O3 particles concentration in plating solution. The wear rate of the Ni-Al2O3 composite coating fabricated via SCD technique with 10g/l nano-Al2O3 particles in plating bath is approximately one order of magnitude lower than that of pure Ni coating. Wear resistance for SCD obtained composite coatings is superior to that obtained by the CEP technique. The wear mechanism of pure Ni and nickel nano-Al2O3 composite coatings are adhesive wear and abrasive wear, respectively.