Study On The Friction And Wear Properties Of Water-Lubricated Rubber Stem Tube Bearing Reinforced By Silica

Water-lubricated stern tube bearings are an important part of the ship propulsion system,and the bearing material quality is the premise to ensure the normal operation of water-lubricated bearings,specially the friction and wear characteristics,which directly determines the reliability and stability of the water-lubricated bearing.However,at present,domestic research on water-lubricated bearing materials is slightly lacking,and most water-lubricated bearings are also dependent on imports.Therefore,the preparation of new water-lubricated bearing composites,through experimental research on its friction and wear properties,has important theoretical and practical value for improving the reliability of water-lubricated bearings.In this study,three kinds of composite materials were prepared by using nitrile rubber as the matrix material,pure nano-silica,modified nano-silica and micro-silica as reinforcing agents.The effects of rotating speed,load and temperature on the friction and wear performance of the three composites were investigated under the condition of water lubrication,and achieved the following results:(1)The surface modification of nano-silica was carried out by two-step method.The modified nano-silica was characterized by infrared spectrum analysis,thermos-gravimetric analysis and scanning electron microscopy.The results showed that the coupling agent TESPT was successfully grafted to the surface of nano-silica,and the agglomeration of nano-silica reduced.(2)Nitrile rubber/silica composites were prepared by emulsion blending and mechanical blending.The mechanical and physical properties of the composites meet the relevant requirements of the US military standard and the Chinese ship standard.The existence state of silica particles in different composite materials was analyzed from the microscopic point of view,and the influence mechanism of silica on the mechanical properties of composites was described.(3)Based on the SSB-100 water-lubricated bearing test rig,the friction and wear properties of three composite materials were tested.The results of friction test showed that under water lubrication conditions,the rotational speed,load and temperature had an effect on the friction coefficients of the three materials.Under the same working conditions,the modified nitrile rubber/nano-silica composite has the lowest friction coefficient.It is considered that the modified nano-silica has good bonding with the rubber matrix and is not easy to fall off under the action of external force.When sliding,the friction force is mainly composed of adhesion and furrow resistance caused by rigid slightly convex body.(4)The wear test results show that the modified nano-silica/nitrile rubber composite has the Best wear performance under the same working conditions.The reason is that the nano-silica modified by silane coupling agent TESPT has better dispersion in the nitrile rubber due to the reduction of agglomeration,and the presence of TESPT acts as a vulcanizing agent,which increases the crosslink density of the vulcanized rubber and increases the strength of the composite material,and the composite material is difficult to be torn under the action of external force,so the amount of wear is the lowest.