Study On The Preparation, Microstructure And Performance Of Ni/Cu-based Nano-composite Coatings By Electrodeposition

Composite electrodeposition with nano-particles is a developing surface technology. Nano-composite coating is showing more and more excellent performance, such as mechanical performance, catalytic performance, corrosive protective performance and so on. All of this has bought a wide range investigation on it.In this paper, the manufacture technology and current study of electrodeposited composite coatings were introduced. The composition and technologies of the composite coating Ni-W-nano (Si3N4Al2O3) and Cu-nano (Al2O3/SiO2) were studied. The effects of main factors (adding quantity of nano-Si3N4, disperse methods, current density, dispersing agent) on the quality of Ni-W-Si3N4 composite coatings and deposition velocity were also dealt with. Based of it, codeposition mechanism of nano-particles with metal ions was introduced. Many dispersion methods on the nanometer particle for electroless composite coatings have been studied in this paper. At the same time, the microstructures and components of the composite coating Ni-W-nano (Si3N4/ Al2O3) and Cu-nano (Al2O3/SiO2) were characterized by EDS , XRD and SEM as well as TEM Techniques. Its performance was studied by measuring microhardness, weight loss method, anodic polarization curve and EIS.The results showed that the wt% of the nano- particles in the deposited layer increased as the wt% of the nano-particles increased in the electrolyte; the wt% of the nano-Si3N4 particles in the deposited layer Ni-W-nanoSi3N4 increased as current density increased in the electrolyte. When Dk was 20A/dm2, the wt% of the nano-Si3N4 particles in the composite was up to 8.3% and the morphology of the composite was best; the wt% of the nano-Al2O3 particles in the deposited layer of Ni-W-nanoAl2O3 also increased as the temperature increased in the electrolyte. However, when the temperature above 75°C, the increasing rate of the wt% of the nano-Al2O3 particles in the composite was slow.The results showed that Nano-particles was dispersed sufficiently and homogeneously, at the same time, the content of nano-particles in the coatings increased. The corrosion resistance of the composite coating Ni-W-nanoAl2O3 is excellent in 3.5wt%NaCl solution.