Homogeneous electroless Ni―P/SiO2 nanocomposite coatings with improved wear resistance and modified wear behavior

Highly homogeneous Ni-P/SiO2 nanocomposite coatings were prepared by electroless deposition from composite baths containing well dispersed SiO2 nanoparticles. The particle concentration in the coatings increases gradually with the SiO2 concentration in the bath and reaches an observed maximum of 25vol.% at a bath concentration of 10g/l. Tribological measurements of the heat treated coatings indicate that while the hardness of the coating is decreased compared to that of the Ni-P coating without particles, an improvement in Pin-on-Disk wear resistance up to a factor of 2 can be achieved. The aspect ratio of the wear track of samples heat treated above 270A degree C is found to increase with the concentration of nanoparticles in the coatings. This observation indicates that the nanoparticles also modify the wear behavior of the coatings.