Tribological analysis of ultra-high molecular weight polyethylene composites with boron carbide micro and nanoparticles

The goal of this study is to investigate the tribological and morphological changes obtained by addition of boron carbide (B4C) micro and nanoparticles into Ultra High Molecular Weight Polyethylene (UHMWPE/B4C). In this work, UHMWPE was reinforced with B4C micro, nano (powder) and nanoparticles prepared using pulsed laser irradiation in liquid by solvent mixing (SM). Subsequently, the mixtures were compression molded at 180 °C and 15 MPa for 15 min, then cooled for 5 min at different concentrations (0, 0.1, 0.3, and 0.5 wt%) to evaluate the thermal, mechanical, and tribological behavior of these composites. Studies on changes in the structural and morphological characteristics of the composite samples were carried out by means of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The microhardness and scratch hardness of the composites were measured using a diamond indenter revealing nanoparticles outperformed micro-particles in both properties. In addition, the tribological behavior of the hot-pressed composite structures was analyzed via a scratch test machine using a normal load of 10 N and a ball-on-disk tribometer with a normal load of 30 N. As a result, the wear resistance of the composite revealed significant improvement up to a certain amount of particles. The coefficient of friction was also reduced. Worn surface analyses were done on the composite using the confocal and scanning electron microscopy (SEM), indicating various wear mechanisms such as delamination, micro-cutting, micro-plowing, and groove-formation. The composites showed low wear rates and were correlated with scratch hardness.