Friction and Wear Behaviors of the Polydimethylsiloxane Bishydroxyalkyl-Terminated Modified Polyurethane Composites Filled with the Barium Sulfate in Dry Friction and Water Lubrication

The addition of less than 20 wt% of approximate 1 micron barium sulfate (BaSO₄) into polyurethane (PU) composites modified by bishydroxyalkyl-terminated polydimethylsiloxane (PDMSBH) resulted in increases in mechanical strength and thermal conductivity and, at the same time, resulted in improvements in the friction and wear properties of the polyurethane composites. These polyurethane composites were suitable for marine use for bearings at high load under dry friction and at fast sliding speed under water lubrication. Characterization with Fourier transform infrared (FTIR) spectroscopy, thermogravimetry analysis (TGA), scanning electron microscope (SEM), and an MRH-3 ring-on-block wear tester indicated that the addition of BaSO₄ disrupts the organic phase separation in the polyurethane, resulting in better tribological properties, but there is no special chemical reaction between the particles and polyurethane. Adding too much BaSO₄ resulted in higher wear rate because of inorganic–organic phase separation.