Study On The Mesoscopoic Surface Mechanical Properties Of The Porous Self-lubricating Sintered Material

In this paper, the structure character, sintering technique, and the forming mechanic of a surface films for the porous self-lubricating sintered material are analyzed. For a porous self-lubricating sintered material that obtained by infiltrating solid lubricants to the micro-pores matrix in the high-temperature with melting percolation method, its mechanic character of mises is studied. When two objects mutually contact and have a relative movement, because of the matrix stress, heat friction, and so on, these roles will lead to the lubrications within the micro-pores matrix to the surface and coat the surface of the micro-pores matrix, forming a compensation role of the lubricating film. Thus a sintered material element model with more self-lubricating characters is established. Basis of homogenization theory, assuming that the micro-pores matrix structure is a cyclical distribution, and with finite element analysis techniques for different matrix / lubricating film thickness (H₂/H₁ ), porosity (ε), analyze the von Mises stress and shear stress trends. The main conclusions of the study are the following four:(1) Self-lubricating sintered material element model substrate thickness and the surface lubricating film thickness ratio greater than or equal to 10, which can show the surface stress trends of the sweat glands self-lubricating sintered material.(2) The elastic modulus of the soft metal lubrications is smaller than the elastic modulus of the matrix, therefore, porosity in matrix material will have an impact on the compact , strength, and toughness, and the friction surface properties of the self-lubricating sintered material. When the porosity is 20% and full of lubrications, then could meet the general self-lubricating bearings lubricant coverage requirements, and offer compensation.(3)In the matrix material near the edge of the pores, there are big stresses, and large deformations, when the objects on the surface and have a mutual contact and sliding (roller) fixed, which would conduce to the extrusion of the lubricants, but alternating load will diminish pore strength, the edge of the micro-pores rupture, and then plug these micro-pores, hinder lubrications infiltrating.(4) Through studying regional deformation around the hole diameter a of the material surface and the pore diameter d, the two forms can be found:(1)when a =d , the micro-cracks or micro-fractures may occur in somewhere of the micro-holes Edge; (2)when a >d, the micro-cracks or micro-fractures may occur in somewhere of the central of these micro-pores.