A Novel Hydrophilic PVA Fiber Reinforced Thermoplastic Polyurethane Materials for Water-lubricated Stern Bearing

Abstract

As an important part of the marine propulsion system, the water-lubricated stern bearing has a major impact on ship safety. In order to improve the reliability of water-lubricated stern bearing under actual working conditions, hydrophilic PVA fibers were added to a typical water-lubricated bearing material, the thermoplastic polyurethane (TPU), to fabricate TPU/PVA fiber composites. The sliding friction-wear test, under water-lubricated conditions, of the TPU composites/QSn7-0.2 friction pairs were analyzed using a designed testing apparatus. The friction coefficients, worn surfaces and the wear losses from the test samples were examined. The results revealed that the addition of appropriate hydrophilic PVA fibers can effectively improve the tribological properties of TPU materials. The hydrophilic PVA fibers not only improved the affinity and the material surface storage ability to water medium but also absorbed water and formed swelling convex texture under water environment, thereby enhanced the hydrodynamic lubrication effect. When the mass fraction of PVA fiber reached 15 % or more, the debris gathered under the action of loading and fiber connection, formed solid lubrication film. Thus, it effectively improved the self-lubrication performance of the material. But that is not conducive to the tribological performances of the composites when the mass fraction of PVA fiber reached 30 %. Generally, the materials with 15 % to 20 % PVA fiber content showed better tribological properties under the experimental conditions. This work provides a new idea for the research of new water-lubricated bearing materials.