Effect of SiO2 and MoS2 nanoparticles on microstructure and wear resistance of electroless nanocomposite Ni-P-SiO2-MoS2 coating

In this research, electroless nanocomposite coating of Ni-P-SiO2-MoS2 and effect of SiO2 and MoS2 nanoparticles on microstructure and wear resistance of coating were investigated. First of all, samples from MO40 (AISI 4140) steel sheet were prepared and coated in Nickel-Phosphorous electroless bath containing 7 g/l SiO2 and MoS2 particles in 90°C and 6.4 pH for 60 minutes. Then, pin on disk wear test was performed to evaluate the wear resistance of the coated and uncoated samples. Several experiments used to explore tribological features of deposited electroless coatings. Field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) images were taken to investigate coating microstructure and its elements, respectively. Microstructural results showed that a uniform coating on substrate was successfully composed. Also, several mechanisms observed during the abrasion process. Abrasive and adhesive mechanisms were active in uncoated samples, but by applying SiO2 and MoS2 nanoparticles, the sliding mechanism was activated. Furthermore, with decreasing friction coefficient, wear resistance increased by 79.3% and also the tribological properties of the sample improved.