The effect of TiO_2 nanoparticle codeposition on microstructure and corrosion resistance of electroless Ni-P coating

摘要

Ni-P-TiO_2 nanocomposite coatings with various contents of TiO_2 nanoparticles were synthesized by adding TiO_2 nanoparticles to Ni-P electroless plating solution. The effects of pH and anionic surfactant sodium dodecyl sulfate (SDS) on the chemical composition of Ni, P, and TiO_2 in the coatings were investigated. Scanning electron microscope (SEM), energy dispersive spectrometer (EDX), and X-ray diffractometer (XRD) were used to characterize the morphology, composition, and crystal structure of deposited coatings, respectively. The hardness of nanocomposite coatings was improved greatly compared to Ni-P coating especially after heat treatment. After heat treatment at 400℃ for 1 h, an increase in microhardness was observed for heat-treated Ni-P coatings. The hardness was increased from 805 to 1050 Hv for Ni-P-TiO_2 coating deposited at 9 g/L TiO_2 concentration in the bath. The corrosion resistance of Ni-P-TiO_2 coating was significantly increased compared to Ni-P coatings by incorporation of TiO_2 nanoparticle.