Design And Simulation Analysis Of Micro-porous Structure In Infiltration-type Self-lubrication Composites Matrix

As a type of self-lubricating materials, the infiltration-type self-lubricating composite was using the principle of bionic tribology. The process of preparation of the material can be divided into two parts:(1) preparation with the matrix which has micro-porous structure;(2) infiltration of solid lubricant. In the friction process, the matrix plays a role of bearing load to ensure the toughness, and the main function of solid lubricant is to reduce the friction coefficient of friction surface. The micro-structure of matrix is the precondition of lubricity of composites. Because the micro-porous structure(such as pore size, distribution and shape) decided the infiltration of solid lubricants, the distribution uniformity of solid lubricants and whether can form lubrication film in friction surface.The micro-porous structure of melt infiltration self-lubricating composite was taken as the research object in this paper. Based on the homogenization theory and the finite element analysis method, the micro-porous unit-cell model was established and the porosity and micro-structure was simulated analysis. Based on the performance requirements of infiltration-type self-lubricating composite, the influence of the structure characteristic parameters(such as the porosity, pore-shape, pore-size distribution) on the properties of composite was studied. According to the design principle of matrix, the materials were designed and the matrix was prepared by using the powder metallurgy technology.According to the theory analysis results of infiltration-type self-lubricating composite matrix, porosity was an important structural characteristic parameters of composite materials. The strength, hardness and self-lubricating performance of composite were affected by porosity. Porosity has nothing to do with the diameter of powder particle, but with the morphology and arrangement. When the shape was a spherical particle, the porosity of matrix was smaller. The porosity increased and the relative density decreased with the characteristic parameters. With the increased of porosity, relative elastic modulus decreased and poisson’s ratio increased, while compressive strength declined. In order to ensure the requirements of mechanical properties and self-lubricating of composite, the porosity should be in the range of 15% to 30%.The unit-cell model was carried on the finite element simulation analysis. The results show that the Mises equivalent stress and the strain were increased with the increased of load, when the pore shape was circular, triangle, square and hexagon, respectively. But the rate of increase was different, the circular was slower and hexagon was faster. With the increased of porosity, the Mises equivalent stress was increased while the strain was decreased. By comparing, the comprehensive performance of composite was better when the pore shape was circular or square.The matrix was prepared by using FeCrWMoV alloy powder for the metallic phase and TiC powders as ceramic phase, and adding a certain volume fraction of compound pore-forming agent. The results show that micro-porous distribution of the sintered sample surface was uniform. The pore shape was the circular or square. The internal structure of sintered sample was similar to the structure of human body sweat glands. The porosity was increased with the increasing of compound pore-forming agent content. As the rising of sintering temperature, the micro-hardness was increased. The crushing strength of sintered sample was decreased with the increasing of porosity. The pore shape was influenced by the holding time. The crushing strength was higher when the holding time was 60 min.