The Study Of Thermal Driving Mechanism Of High Temperatiure Sweating Lubrication And Its Stablity

The high temperature sweating lubrication material is a new kind of material compounded solid lubricant in micro-pores of a gland type metal ceramic matrix. The mechanism of it is that, under the effect of frictional heat and stress of high temperature, the solid lubricant in the micro-pores of matrix is driven along its channels to the friction surface forming self-compensating film by diffusing (infiltrating and sweating). Thus, the performance of high temperature sweating lubricating rests not only on the micro-pore structure of material, but also on the driving force in process of high temperature friction. This study has been supported by the National Natural Science Foundation.According to the preparation theory of sweating lubrication materials, the influence of components arrays on the pore structure is analyzed. A result of the analysis is that the volume of micro-pore is enough and the rigidity is stronger because of the rhombic hexahedron array.By using micro-analysis, the components and the lubricating characteristic of generated film on the sweating self-lubricating surface are analyzed. The study results indicate that the penetrability in the solid lubricants of soft metal Pb element is better than the Sn element. When the average covered area is 31. 67%, the frictional coefficient is lower.A sweating self-lubricating covered somatic cell model is established. The principle of thermal driving force for the lubricants in the model is studied from both theory and experiment. The study shows, the impregnating and effusive progress of the lubricants in a matrix are related to the structure and the thermal driving force.In order to discuss the thermal stability of the dynamic lubricating film, a method of numerical analysis of frictional heat-stress coupled field at dynamic contact is brought forward in the thesis. As a representation, the transient increase of frictional temperature under the dynamic contact in a pair of sliding bearings is computed. The contour plot of thermal stress distribution is drawn also. The generating process for the film of sweat-lubricating material can be analyzed founded on the thermal driving force.Based on the characteristic of the surface micro-pores structure of sweating material, a finite element analysis model of mesoscopic surface layer stress was modeled. The relativity between porosity and stress is analyzed by the model. The study shows, the stress concentrations of surface layer occur at pore edges in the interface that are between lubricating film and matrix. The stress concentrations become severe increasing the porosity and the intensity of matrix and the structure of open pores affect the continuity of lubricating film.The analysis method of linear elastic fracture mechanics and thin film theory was introduced for the study of the stability of the surface film of sweat material. The study shows, the buckling delamination of surface film with micro-structure matrix is possible, and the critical radius of buckling delamination is 142.5μm. It is demonstrated in theory that for the self-lubricating material with surface micro-pore structure the failure of buckling delamination will not take place if the environment temperature is 20-700℃and the diameter of the surface pore is about 20μm,...