Preparation And Properties Of Ni-TiO₂Nanocomposite Coatings By Electrodeposition Method

The advantages of nanocomposite coatings not only have properties such as highhardness, wear resistance, corrosion resistance, high temperature resistance, electricalconductivity, magnetic, but also good control of operation. In many nano materials, nano TiO2is regarded as a promising material owing to non-polluting and photocatalytic activity. So,there is a wide range of applications of Ni-TiO2nanocomposite coating in painting, ceramics,water treatment, air purification, sterilization, etc.In this paper, Ni-TiO2nanocomposite coatings are prepared by electrochemicaldeposition of Ni and anatase nano TiO2onto surface of316L stainless steel in the watts nickelplating.The influence of TiO2nano-pariticulates concentration, cathode current density,electroplating time and stirring method on the surface morphology or nano TiO2content ofNi-TiO2nanocomposite coating are investigated. And the adhesion force, microhardness andwear resistance et al of the Ni-TiO2nanocomposite coating are tested as well.The optimal process conditions are: TiO2concentration in the plating solution:15g/L;cathode current density:3A/dm2; electroplating time:60min; stirring method: magneticintermittent stirring. X-ray diffraction (XRD) and scanning electron microscope (SEM) areused to analyze coatings. The surface morphology of Ni-TiO2nanocomposite coatingprepared with the process conditions is flat, dense, no cracks and the grain is small. TheNi-TiO2nanocomposite coatings show a preferred orientation along the Ni (111) plane.The mechanical property of Ni-TiO2coatings is investigated by stress bending tests,microhardness tests and wear tests. Ni-TiO2nanocomposite coating shows a good bindingwith the substrate and higher microhardness value,1241.5HK, than pure nickel coating andstainless steel substrate. Wear resistance of Ni-TiO2nanocomposite coating is much betterthan that of the pure nickel coating. The friction coefficient of Ni-TiO2nanocomposite coatingreduces by62%compared with that of pure nickel coating. The Ni-TiO2nanocompositecoatings obtained with15g/L TiO2particle adding in the plating solution show the minimumwear rate, meanwhile, the coatings exhibit high TiO2content and small grain size.