Study On Preparation Of UHMWPE Modified Water Lubricated Bearing Material And Its Friction And Wear Properties

As the rotating body that supports the shaft system to transmit power,water-lubricated stern bearings are the significant components of the ship propulsion system and their operational reliability plays a crucial role in the navigation safety and the operational performance of the entire ship.Based on the excellent mechanical and physical properties,high load-bearing capacity,and high impact resistance,water-lubricated stern bearings have been widely used since they were born.However,China still relies heavily on importing the materials of water-lubricated stern bearings from developed countries as we are not able to produce most of the them domestically at the moment,in the meanwhile,we are lacking of the systematic research on the formula design principles and friction ＆ abrasion mechanism of water-lubricated rubber-plastic composite stern bearing materials.Therefore,based on the relevant knowledge of materials science,this article aims at designing a reasonable formula for water-lubricated stern bearings materials,focuses on the study of the different composition structures and the influence principle of each component of the materials,and explores the wear performance and lubrication mechanism under conditions of water-lubricated.This will be of great importance for understanding the formula design and lubrication mechanism of water-lubricated rubber-plastic composite stern bearing materials,rational design and optimization of their tribological properties.Specially speaking,this research used nitrile rubber as the matrix,and the amount of added UHMWPE as the variable,supplemented by additives such as graphite,carbon black,zinc oxide,etc.,to prepare different parts of UHMWPE modified nitrile rubber water-lubricated stern bearings test block,and then explored the friction and wear performance of different parts of the composite material under different speeds,different loads and different lubrication conditions through a series of friction and wear performance tests and surface micro-morphology analysis,and the main results have been summarized as follows.（1）Produced four materials of water-lubricated stern bearings of which the mechanical and physical properties have met both the Chinese ship standards and the US military standards by adopting the UHMWPE material of the GUR4050-3 model with a higher average molecular weight and a smaller average particle size of Celanese,referring to the basic formula of nitrile rubber in the ASTM standard formula.（2）The Rtec-MFT5000 friction and wear tester ring-block module was employed to test and compare the friction and wear properties of the four composite test blocks and the pure UHMWPE test blocks and the friction test results indicated that: It is confirmed that adding UHMWPE will reduce the friction coefficient of the composite material: Under the same load conditions,the friction coefficients of test blocks from different materials generally showed a law of gradual decrease with the increase of rotational speed and tended to be stable;Under the condition of fixed speed,the friction coefficient of different materials decreases with the increase of load,but the effect is not obvious;under the same working conditions,the friction coefficient of the material decreases with the increase of the number of UHMWPE added parts.（3）According to the test results: Under the condition of water lubrication,the wear of composite material decreases with the increase of UHMWPE added parts.Combined with the surface morphology analysis of test blocks of different materials and copper rings,the anti-friction mechanism of composite materials have formed a NUG network-like structure for the particle of UHMWPE with a peeled surface of composite rubber and matrix,which has greatly increased the contact area,and under the action of friction heat,it starts to form an anti-friction transfer membrane on the surface of the copper ring between the micro convex.