Friction and wear studies using Taguchi method on polyphenylene sulfide filled with a complex mixture of MoS2, Al2O3, and other compounds

The tribological behavior of polyphenylene sulfide (PPS) filled with molybdenum-concentrate (MC) deposit from Armenia was studied. The deposit MC was a complex mixture of compounds such as MoS2, SiO2, CuS, Al2O3, and others. Whereas MC as the filler in particulate form reduced the steady state wear rate of PPS, the optimum reduction in wear was found to occur with the addition of polytetrafluoroethylene (PTFE) along with PPS. The behavior of PPS composites made with MC and PTFE sliding against a steel counterface was investigated as a function of the MC and PTFE proportions, sliding speed, and counterface roughness. For this purpose, pin-on-disk configuration and the design of experiments approach utilizing Taguchi's orthogonal arrays were used. Of all the above factors, the change in MC proportion, while PTFE was also present, had the greatest effect on the reduction in wear rate. The variation of the coefficient of friction was found to be in the narrow range of 0.27-0.33. The lowest wear rate was found in the case of PPS + 17 vol.% MC + 10 vol.% PTFE composite sliding at 1.5 m/s against a counterface roughness of 0.1 μm Ra. Optical and scanning electron microscopy of the transfer films were performed for observation of the features such as coverage, thickness, topography, and bonding. Friction and wear results are discussed in terms of these observations.