Study On Preparation And Performance Of Ni-carbon Nanotubes Composite Coating

As the rapid development of technology, single structure of materials can’t meet the demand of industry, so there is a strong demand of composite materials with excellent performance. Nano-composite electroplating as a rapid developing technology in recent years materials is widely used in industry. As a unique nanomaterial, carbon nanotubes have excellent properties. In this paper, carbon nanotubes were used as strengthen phase and Ni-carbon nanotubes composite coatings were prepared by using electrodeposition. The contents and conclusions of this study were as follows:(1) Modified the carbon nanotubes using mixed acid, first. The result of SEM shows that the oxidation of carbon nanotubes by mixed acid could reduce its length-diameter and weaken its agglomeration tendency. IR shows that the surface of carbon nanotubes has active group. XRD shows that the crystallinity of carbon nanotubes is better after treatment by mixed acid. The dispersion of carbon nanotubes in water and composite coatings has greatly improved after modified. The settlement test shows that16Y was the best dispersant.(2) Effects of carbon nanotubes concentration, current density, stirring speed, pH value, temperature, dispersant content and plating time on carbon nanotube content and thickness of Ni-carbon nanotubes composite coatings. Determine the optimum technological condition by orthogonal optimized experiment. The results show that the composite coatings have compact surface, the thickness of the composite coatings is reach to42.73μm.SEM shows that carbon nanotubes like grid distribution in the coatings, EDS indicates that the coatings contain Ni, O, C three elements, the contents of them are83.35%、14.18%、1.96%, respectively, so the carbon nanotubes and Ni realized codeosition.(3) SEM shows that composite coatings have a rough surface compared with pure nickel coating and nickel deposition on the surface of carbon nanotubes. At the same time, with the content of carbon nanotubes in solution increased from1g/L to4g/L, the weight percentage of C in the composite coatings increases from10.49%to14.18%. XRD demonstrates that grain size of the carbon nanotubes is smaller than pure nickel coating. The combining power test shows that composite coatings has good adhesion. Tafel plots shows that composite coatings have a better corrosion resistance that pure Ni coatings. Electrocatalysis experiment shows that as the concentration of carbon nanotubes in solution from Og/L to4g/L, the exchange current density increase from6.58×10-8A/cm2to3.89X10-7A/cm2, the ability of electrocatalysis is improved.(4) Ni2+electrodeposition behavior was studied by electrochemical workstation. Cyclic voltammetric curves show the deposition rate of Ni increase with the increase of scan rate. Cathodic polarization curves show that the additions of carbon nanotubes, complexing agent, dispersant, brightener increase the cathodic polarization and improve the quality of the composite coatings.