An Investigation Into Water Lubrication Performance Of UHMWPE Reinforced With Oriented Fibers

With the acceleration of the green process of the shipbuilding industry,the use of water-lubricated bearings is becoming more and more extensive.However,the waterlubricated bearings used today are prone to severe friction and wear under low speeds and heavy loads.In order to improve the service life and reliability of water-lubricated bearings,it is imperative to research water-lubricated bearing materials with better performance.Ultra-high-molecular-weight-polyethylene(UHMWPE)has great development potential in the field of water-lubricated bearings.The tribological properties of UHMWPE can be further improved by fiber modification.Considering the anisotropy of the fibers,the tribological properties of the composites may be further improved by orienting the fibers reinforced UHMWPE.Therefore,the oriented fiber reinforced UHMWPE composites need to be studied urgently.The purpose of this dissertation is to investigate the effects of fiber orientation,fiber density,and different fiber characteristics on the tribological properties of UHMWPE-based oriented fiber composites in water environment and their mechanisms.In this dissertation,the preparation of oriented fiber reinforced composites was realized by special mold and hot-pressing process,and oriented fiber reinforced UHMWPE composite materials were prepared by using fibers oriented in different directions.Effect of fiber orientation on the friction properties of composites under water lubrication was studied.The results show that the mechanical properties and tribological properties of UHMWPE reinforced with fibers oriented in the axial direction were significantly better than those of randomly oriented fiber composites and pure UHMWPE.By changing the density of polyester fibers(PETF),a series of oriented fiber reinforced UHMWPE composites with different densities were prepared.The effects of fiber density on the friction and wear properties of the composites under water lubrication were studied by mechanical tests and tribological tests.The results show that the higher the fiber density,the better the mechanical properties of the composite,but there is obvious edge effect.Under larger load conditions,if the fiber density was too large,the friction and wear properties of the composite will be reduced.For UHMWPE composites reinforced with polyester fibers oriented in the axial direction,the optimal fiber density under test conditions was between 1.1wt% and 2.2wt%.By comparing the mechanical properties and tribological properties of oriented fiber composites prepared from sisal fiber(SF),carbon fiber(CF)and PETF,the effect of different fiber properties on the performance of oriented fiber composites were discussed.The results show that the better the mechanical properties of the fiber,the better the stability of the fiber support,thereby improving the friction and wear properties of the composites;the worse the fiber wear resistance,the easier the composite material is to wear;the wettability of the fiber will change the wettability of the composite material,For water-lubricated bearings,the hydrophilicity of the fibers is beneficial to improve lubrication conditions.In actual use,appropriate fibers or multiple fibers should be selected according to the needs.