Study On The Tribological Properties Of Porous Self-lubricating Composites And Finite Element Simulation Of Properties

Owing to the characteristics of rich porous structures, the porous polymer based self-lubricating composites can absorb and store oil or grease within the matrix. During the friction process, oil or grease can be released continuously and stably to the surface to reduce the friction. The lubricating oil film is formed on the contact surface which contributes the improvement of tribological performance. Hence, the porous self-lubricating composites have broad application prospect.An attempt had been made to prepare porous polymer based self-lubricating composites.The effects of contents of pore-forming agent and lubricant on the friction and wear properties of composites were studied. The wear mechanisms were discussed based on the SEM observations of worn surfaces, counterpart surfaces and cross-section. To further reveal the inherent mechanism of porosity and tribological properties and self-lubrication film formation, the finite element analysis was used. The main contents of this work are summarized as follows.1. PEEK was used as matrix, lithium base grease as lubricant, Na Cl as pore-forming agent. The porous PEEK self-lubricating composites were prepared by molding-leaching and vacuum melting process under high temperature condition. The friction coefficient, wear rate and contact temperature were tested by the experimental methods. The effects of pore-forming agent and porosity on the structure and tribolotical properties of porous PEEK composites were discussed. Based on the friction heat characteristics of PEEK composites under the continuous ring rotating friction movement, a two-dimensional axisymmetric model was established by using the finite element method. The effect of porosity on the temperature,stress and displacement distributions was studied. And the results showed that the error value of predicted and experiment temperature was less than 7%. The simulation method is helpful to study the preparation and control of tribological performance of porous PEEK composites.2. The porous self-lubricating PPS composites were fabricated. The experiment results showed that the friction coefficient, wear rate and contact temperature were lowest when the content of Na Cl was 30 wt.%, porosity was 21%, which were 0.026, 3.75×10-16m3(Nm)-1 and44.3oC. When compared with pure PPS, the frictional coefficient decreased by 90% and wear resistant improved by 1.3×104 times. According to the microcosmic principle diagram of porous composites, the 2D RVE model was designed. By the simulation of material friction movement, the temperature and stress distributions of composites were studied in the3. heat-stress coupled field. At the same times, the effect of pore structures and porosity on the quantity of lubricating grease. The self-lubricating mechanism was revealed.4. The self-lubricating epoxy composites containing the ACs-oil powers were fabricated. ACs-oil powers were distributed uniformly in the EP matrix. The effects of the ACs-oil powers contents on the tribological properties of composites were discussed. The experiment results indicated that the friction coefficient and wear rate were 0.47 and11.5×10-14m3/Nm when the content of ACs-oil powers was 10%. Compared with pure EP, the friction coefficient decreased by 26% and wear resistant increased by 3.21 times. The self-lubricating mechanism was discussed by the SEM and EDS analysis.