Abstract:Electro deposition of nickel and composite coatings has been developed as an advanced environmentally-friendly surface treatment technology for replacing chromium elctro-plating. In this research, pure nickel, nickel-phosphorus and their composite coatings have been electro-deposited on aluminium alloy surfaces. The surface morphology, component and structure are studied by SEM, EDS and XRD. Microhardness tester and electrochemical workstation are used to investigate the hardness and anti-corrosion properties. The results showed that the surfaces of SiC composite Ni coatings were roughness and the profile of NiP cells is distinct on NiP-SiC composite coatings. The structures of NiP-SiC composite coatings included crystalline Ni2P, Ni12P5 and amorphous NiP. The microhardness of NiP coatings on Al substrates was higher than that of pure Ni coatings. Introducing SiC nanoparticles to form composite coatings would improve the microhardness. Furthermore, SiC nanoparticles would increase the corrosion electric potential of the composite coatings in NaCl solution and decrease the electric current density, resulting in better anti corrosion properties.