Experimental Study On The Tribology Properties Of Nano-MoS₂ Water-lubricated Rubber-Plastic Stern Tube Bearing

The water lubricated bearing has been widely used since it was born,not only because of its excellent vibration and noise reducing capability but also its good impact resistance,and good comprehensive performance especially friction and wear performance of bearing material is the prerequisite of its normal working condition,which directly affects the ship safety and the service life of shaft system.But most of water lubricated bearing materials still rely on foreign technology.And there have no strong theoretical knowledge of the lubrication mechanism of water lubricated rubber and plastic stern bearing.Thus,studying on the friction and wear properties of water lubricated stern bearing and exploring the difference of various bearing materials through experiments have a great theory value and practical significance which can improve the tribological performance of water lubricated stern bearing.This experiment using rubber and plastic（NBR and UHMWPE）as basic material,adding MoS₂ with different particle size and additive amount,the friction and wear properties of various materials in different conditions of load,rotational speed and lubrication were analyzed.The main work and research conclusions are as follows:（1）Fluent software is applied to achieve the simulation of water films’loading mode of whole bearing and single test block,which provides some theoretical support for friction performance test.（2）This paper summarized a set of preparation methods for MoS₂ rubber-plastic composite materials,the physical and mechanical properties of the compound have satisfied the ship industry standards of the People’s Republic of China CB/T796-2008 and U.S.military standard MIL-DTL/1790 C（SH）.The basic structure of rubber-plastic materials and the distribution of MoS₂ were analyzed by the microscopic view,and the mechanism of MoS₂ influence on the mechanical properties of rubber matrix was also discussed.（3）The experiments of friction coefficient and wear rate of composites are carried out on SSB-100V Ship Stern Bearing Test Bed and Akron Abrasion Machine.The results shows that both the rotational spped and pressure have an impact on the friction coefficient;the friction coefficient of all the materials decrease and then increase accordantly with the increasing of MoS₂ addition under the same condition,and in most cases,the friction coefficient of nano-MoS₂ rubber and plastic bearing material is smaller than that of micron MoS₂ one.When the additive amount of MoS₂is 9phr,experiment get the lowest friction coefficient under water lubrication,which means the positive and negative factors that affect the friction performance are balanced at this point.The wear amount of composites shows opposite trends under dry-friction and water-lubricated condition,combined with the structural form of the composites and the surface morphology of grinding wheel and copper shaft,it is believed that the performance of wear-resistant layers formed from MoS₂ on the surface of grinding wheel and copper shaft was different.In the fixed distance wear test,the surface morphology and formation mechanism of different relative speed under water-lubricated condition were analyzed.