Electrodeposition of sol-enhanced nanostructured Ni-TiO2 composite coatings

A novel electroplating method has been developed to produce nanocrystalline metal-matrix nano-structured composite coatings. A small amount of transparent TiO2 sol was added into the traditional electroplating Ni solution, leading to the formation of nanocrystalline Ni-TiO2 composite coatings. These coatings have a smooth surface. The Ni nodules changed from traditional pyramid-like shape to spherical shape. The grain size of Ni was also significantly reduced to the level of 50 nm. It was found that the amorphous anatase TiO2 nano-particles (∼ 10 nm) were highly dispersed in the coating matrix. The microhardness was significantly increased from 320 HV100 of the traditional Ni coating to 430 HV100 of the novel composite coating with 3.26 wt.% TiO2. Correspondingly, the wear resistance of the composite coating was improved by ∼ 50%.