Microstructure, friction and wear analysis of thermoplastic based composites with solid lubricant

Thermoplastic based composites containing different weight fractions of molybdenum disulfide (MoS2) solid lubricant were developed by injection molding. Polymethyl methacrylate (PMMA) and polycarbonate (PC) were chosen for the thermoplastic matrices. In order to characterize the interfacial adhesion between the matrices and the filler, we observed the fracture morphologies of selected composites. Micrographs of the fractured surfaces showed removal of MoS2 particles by microcraking as well as the presence of voids in the case of PMMA/MoS2 composites. These observations were confirmed by complementary images obtained using the X-ray tomography. The addition of an appropriate coupling agent may improve the adhesion between the MoS2 particles and the polymer matrix. Tribological behavior of the composites was also investigated using a ball-on-flat microtribometer with a high chromium steel ball antagonist. It was found that the addition of MoS2 particles didn't improve the tribological performance of the composite in the case of PMMA matrix unlike the case of PC matrix where the friction coefficient was considerably reduced.