Preparation Of Titanium Complex Grease And Its Tribological Properties Research

Lubricant plays an important role in reducing energy consumption and extending life span of machines.As a new kind of excellent lubricant,titanium complex grease is drawing increasing spread attention of researchers.However,there is lack of systematic researches on titanium complex grease.Mechanism for synthesis of titanium complex grease has not been fully explored.The studies on the relationship between preparation factors,properties and microstructure have not been thorough enough.In terms of the research on tribological modification,the optimal ratios of various antifriction and antiwear agents have not been accurate enough.The application of titanium complex grease on solid film is too limited,which waits for expanding.These problems above restrict the production and application of titanium composite greases.In this paper,based on the above problems,the following research is carried out.Titanium complex grease was successfully prepared,and the ratios of thickeners and the viscosity range of base oil were determined.The process of synthesis of titanium complex grease was inferred by infrared spectrum analysis,and the synthesis mechanism of titanium complex grease was explored from the chemical reaction insight.According to the influence of solid-liquid dispersion system and the viscosity of base oil on the grease synthesis,the synthesis mechanism of titanium complex grease was discussed from the pers pective of soap oil interaction.As three factors in the preparation for titanium complex grease,process,base oil,and thickeners are selected.Titanium complex greases were prepared based on different level of each factor,and soap fibers were extracted and characterized.The preparation for each titanium complex grease sample and the characterization on soap fibers established the experimental base for properties of physics,rheology,and tribology for titanium complex grease.The properties of physics,rheology and tribology of titanium complex greases based on different levels of various factors(preparation process,base oil and thickener)were studied in detail,and the effects of the levels of each factor on the properties of physics,rheology and tribology of each grease sample were revealed.The influence of the morphologies of soap fibers on the properties of physics,rheology and tribology of titanium complex greases was analysed,which provided a structural basis for the difference of the properties of physics,rheology and tribology on the microscopic level of the soap fibers.The study of tribological modification of titanium complex grease was carried out,selecting nano graphite,graphene and potassium tetraborate as antifriction and antiwear agents.The optimal concentration of each single additive was obtained by four-ball test.The synergistic concentrations of the three additives were determined as 0.831%,0.053%and 2.589%respectively based on the central composite test-response surface analysis method.Reseaching results have shown that synergistically modified grease possesses superior friction reducing and anti-wear properties to grease without additives and containg single additive.SEM and XPS were used to analyze the worn surface of the synergistically modified grease,and a model of its anti-friction and anti-wear mechanism was proposed.The model uncovers the lubricating mechanism as the synersistical effects between physical roles of additives,boundary film,and tribochemical anti-wear film consisting of Fe₃C,Fe₂O₃,Fe OOH,Ti O₂ and B₂O₃.The morphologies of surface of anodic aluminum oxide(AAO)were characterized by white light interferometer(WLI).The tribological properties of base grease and synergistically modified grease applying on AAO film were compared.Average frictional coefficient and worn area,at lighter and heavier load during 1 h friction,were measured by M-200 friction and wear tester.The variations of average frictional coefficient and worn rate with time of 5 h were tested.Compared to base grease,average frictional coefficient,worn area and worn rate have obviously decreased under various testing conditions.By comparing the SEM morphologies of worn surfaces under all the experimental conditions,it was found that the worn surfaces lubricated by synergistically modified grease are much better than those lubricated by base grease,which has verified excellent friction reducing and anti-wear properties of synergistically modified grease.