Reasearch On Manufacturing Technique And Performance Of The Self-Lubricating PTFE-Based Composites

Bearings for cryogenic turbo pumps work in extreme condition of ultra low temperature. The lubricant oil and grease should be avoided in such condition and the solid lubricant is used only. The lubricant film is produced by the bearing cage made of self-lubricating materials. The research on the relationship of the performance of the self-lubricating composites and the manufacturing technique of such materials is very important and it has not been investigated fully. Based on the above mentioned reasons, this thesis focuses on such relationships.According to the manufacturing technique of PTFE-based composites at present, this thesis analyzes the effect of the sintering technique on the tribological performance of the PTFE-based composites, and carries out experiments of sintering with different parameters. The sintering parameters include temperature, time, and changing speed of temperature. The samples are tested by friction and wear tester, and the crystallinity is tested too. The relationship of performance of PTFE-based composites is analyzed with the technique parameters. The results show that the crystallinity rises up when sintering temperature is higher or the sintering time is longer, and the higher crystallinity correlates to lower friction coefficient, lower hardness and lower wear resistance. The technique is finally fixed at 380℃of sintering temperature, 300min of constantly-heating and the crystallizing temperature is 330℃. Based on such technique, the composites with performance of proper wear resistance and low friction coefficient can be obtained.The thesis chooses 5 kinds of PTFE-based composites to sintering with the above sintering technique and carries out experiments with the sintered samples. The experiments include wear test, crystallinity test, coefficient of thermal expansion test, DSC test and PV limit test. The results of wear test, hardness and crystallinity measurement show that the filling materials will lower the crystallinity. As a result, the performance of wear resistance of the composites increases while the friction coefficient increases. The test of thermal expansion indicates the transfer temperature of crystallization and slacking of PTFE-based composites is different because of the filling materials. The transfer temperature...