Tribological Investigation of Composite MoS2-TiO2-ZrO2 Coating Material by Response Surface Methodology Approach

Abstract

Abstract Molybdenum disulfide (MoS2) is popularly used in tribological applications because of its excellent lubricating properties. However, its performance needs to be further improved. In the present study, an attempt has been made to improve the wear resistance of pure MoS2 coating by incorporating TiO2 and ZrO2 nanoparticles as a reinforcement material into the MoS2 base matrix. The composite MoS2-TiO2-ZrO2 coating was applied onto substrate surface by the bonding technique. The tribological performance of the coated specimens was evaluated by employing various operating conditions (such as wt% of compounding elements, contact pressure, and sliding speed) using pin-on-disc friction and wear test rig. A statistical model was developed to identify the significant factors affecting the friction coefficient (COF) and wear-rate of the composite coating material. The design of experiment (DOE) was formulated by response surface methodology (RSM) approach to cut down the number of experiments and to develop a mathematical model between the key process parameters such as wt% of compounding elements, contact pressures, and sliding speeds. Analysis of variance (ANOVA) was executed for checking the adequacy of the empirical models developed. It was discovered that the COF and wear-rate of composite MoS2-TiO2-ZrO2 coating significantly affected by the wt% addition of ZrO2. The SEM and optical microscopy analyses of the worn surfaces and transfer films indicated that the tribological properties of composite MoS2-TiO2-ZrO2 coating were significantly improved compared to pure MoS2 coating.