Influence Of Surface Texture On Tribological Property Of Water Lubricated Bearing Materials

As an important supporting component of the ship propulsion system,the water-lubricated stern bearing has a great influence on the safety,concealment and economy of the ship navigation.With the continuous development of material technology,more and more polymers are used in stern bearing.Among them,Ultra-High Molecular Weight Polyethylene（UHMWPE）is considered as the most popular and reliable material.However,the friction and wear of stern bearing are intensified under the conditions of starting,stopping,low speed and heavy load,so it is difficult to ensure the good lubrication.The surface texture structure has a significant effect on the lubrication performance of friction pair.Therefore,investigating the surface textures of materials at different scales and its effect on the tribological properties of water-lubricated bearing materials,it provides a new method for improving the tribological properties of water-lubricated bearings.At first,three different types of convex macro textures were prepared on the surface of the UHMWPE sample,which were cylindrical structure,cube structure,and cuboid structure.Using the untreated surface sample as a contrast,the influence mechanism of the macroscopic surface texture on the friction and wear performance of the friction pair was analyzed through tribological tests.The results showed that the friction coefficient of convex textured samples were more stable than that of the untreated sample.The wear performance of the cylindrical convex textured sample was better than other convex texture and untreated samples.The cube convex textured sample was the most effective to improve the wear properties at the low sliding velocity of 0.063 m/s.Secondly,9 kinds of ball table structures with different sizes were prepared by3 D printing technology,and the areal density was set to 38%,so as to explore the anti-friction and wear-resistant effects of different ball table structures.The results showed that the average friction coefficient of the ball table structure with a diameter of 3 mm was generally low and the range of variation was not large during the whole dynamic wear test.Under the condition of low speed and heavy load,this kind of surface structure had a lower average friction coefficient,less wear loss and smoother wear surface.Finally,based on the surface morphology of Lignum Vitae after immersing in the water,the composite materials with different contents were prepared by blending UHMWPE with hydrophilic sisal fibers.Due to the different water absorption of the material interface,irregular micro convex structure was formed on the surface after immersing in the water.The influence of the micro surface texture on the tribological properties of the composites were explored using the tribological tests.The results showed that: the higher content of sisal fiber was,the stronger absorbent capacity of SF/UHMWPE composite was.Under the condition of low speed and heavy load,the10% SF/UHMWPE had the best anti-friction performance.In summary,different scale surface textures have improved the tribological properties of friction pairs on different degrees.On the one hand,the surface texture has provided a channel for the water flow,which could improve the formation of the water film.On the other hand,the lubrication performances have been improved by the cavitation and wedge effect of convex surface body.And then,the wear performance of materials and the overall lubrication performance of the friction pair surface are improved.