Effect of SiO₂ Nanoparticles Addition on Tribological and Electrochemical Behaviors of Ni–P–MoS₂ Multi-Component Coatings after Heat Treatment

The tribological and electrochemical properties of various nanocomposite coatings of Ni–P–MoS₂–SiO₂ have been investigated. Such coatings were made by the electroless method and then heated at 400°C for 1 h. The amount of SiO₂ nanoparticles was a factor which changed Ni–P–MoS₂ coatings characteristics. In addition to microstructure evaluations and the phase detection, the microhardness, the friction coefficient, and wear behavior were studied for various coatings. Field emission scanning electron microscopy images demonstrated that SiO₂ nanoparticles were distributed uniformly in the Ni–P–MoS₂ matrix. The obtained results showed that when the concentration of SiO₂ nanoparticles in the deposition bath increased from 5 to 20 g/L, then the microhardness and the wear resistance increased as well. Besides, the friction coefficient reached the lowest value of 0.05. For nanocomposite coatings, the ratio of the friction coefficient to the square hardness was a proper parameter which could predict the wear behavior. Additionally, energy dispersive spectroscopy results showed that the content of SiO₂ nanoparticles in such coatings increased from 4.9 to 11.4 wt %. Corrosion tests demonstrated that the best corrosion resistance was observed for the nanocomposite coating when the concentration of SiO₂ nanoparticle was 20 g/L.