Preparation and characterization of electroless Nia€“Bano-SiO2, Al2O3, TiO2 and CuO composite coatings

摘要

Nia€“B/SiO₂, Al₂O₃, TiO₂ and CuO composite coatings were successfully obtained by the electroless plating technique. Dispersible SiO₂, Al₂O₃, TiO₂ and CuO nanoparticles were co-deposited with electroless Nia€“B coating onto AISI-304 steel substrates. Deposits were characterized for its structural properties by X-ray diffraction (XRD). XRD results showed a broad peak of Nia€“B and low intensity composite nanoparticle peaks. The surface and cross-section morphology of samples were analysed using a scanning electron microscope (SEM). Surface analysis showed that the incorporation in Nia€“B matrix of nano-SiO₂, Al₂O₃, TiO₂ and CuO particles increases the nodularity of composite coatings. The deposits are composed of a columnar structure grown along the vertical direction of the substrate surface. The results also show that electroless nanocomposite coatings tend to have greater microhardness compared with the coating without nanoparticles. The increase in the microhardness of the nanocomposite coatings reported in this study is attributed to an effect of dispersion strengthening of ceramic particles in the Nia€“B matrix.