Study On Tribology Properties Of Ultrahigh-molecular-weight Polyethylene (UHMWPE) Water-lubricated Materials Based On Different Melting Temperature And Molecular Weight

With the continuous aggravation of Marine pollution,each country began to call for the application of green ship technology.Ultra-high molecular weight polyethylene（UHMWPE）has been paid more and more attention in Marine water-lubricated stern tube bearings based on its excellent wear resistance,good impact resistance and unique self-lubrication performance,which can bear extreme working conditions such as low speed,heavy load and start and stop.Due to its ultra-high molecular weight and low shear rate of molten UHMWPE,the preparation process and molecular weight are the main limiting factors for the development of UHMWPE.In this study,molding process was used to prepare several UHMWPE samples.The physical and mechanical properties and surface properties of the prepared samples were measured by shore hardness tester,electronic universal material testing machine,contact Angle measurement instrument,laser confocal measurement equipment and so on.The tribological properties of UHMWPE samples under water lubrication condition were investigated by Rtec-multi friction and wear testing machine.The relationship between melting temperature,molecular weight,UHMWPE structure and friction and wear performance under water lubrication was studied in this study.The main research results are as follows:（1）Six molecular weights of UHMWPE were used as research objects,which were 1.7×10⁶g/mol,3.7×10⁶g/mol,5×10⁶g/mol,6.7×10⁶g/mol,8.7×10⁶g/mol and10.2×10⁶g/mol,respectively.The molecular weights of six kinds of UHMWPE were measured by viscosity method to verify the feasibility of using viscosity method to measure the molecular weights of UHMWPE in each gradient.The results show that UHMWPE with molecular weight of 10.2×10⁶g/mol can be measured by viscosimeter with a diameter of 0.6-0.7mm.（2）Five kinds of UHMWPE samples were prepared by molding process at different melting temperatures.The oxidation degree of UHMWPE at different melting temperatures was measured by a rapid oxygen determination instrument.The samples prepared at different melting temperatures were combined with copper ring(ZCu Sn₁₀Zn₂)as friction pairs to investigate their tribological properties under different loads and speeds in water lubrication environment.The physical and mechanical properties and tribological properties of UHMWPE samples at different melting temperatures were compared to explore the wear mechanism of UHMWPE samples at different melting temperatures under water lubrication.Experimental investigations reveal that the friction and wear properties of UHMWPE samples prepared at 200℃are the best under water lubrication.（3）Six UHMWPE samples with different molecular weights were prepared by plate vulcanizing press with the same molding parameters.The tensile properties of UHMWPE samples with different molecular weights were compared with their tribological properties under water lubrication condition,and the relationship between molecular weight and its molecular structure and tribological properties was explored to further clarification of the wear mechanism of UHMWPE.The result show that the wear of UHMWPE is reduced as the molecular weight increases.The wear mechanism of UHMWPE under water lubrication is mainly abrasive wear,and the material loss form is mainly surface crack,particle stripping and groove.