采用熔融沉积成型(FDM)和热压烧结工艺分别制备机器人关节轴承自润滑聚四氟乙烯/聚醚醚酮(PTFE/PEEK)复合材料,并对复合材料进行热处理改性,采用单因素实验探讨了热处理各阶段(升温、保温、冷却)工艺参数对复合材料摩擦学性能的影响。结果表明:热处理改性可以显著提高FDM及热压烧结工艺成型PTFE/PEEK复合材料的摩擦学性能,但需合理把控升温速率,升温速率过快容易导致材料结晶不充分,劣化改性效果,升温速率为2℃/min时制备的试样摩擦学性能最优;FDM和热压烧结成型试样对应的最佳保温温度分别为210℃和205℃,过高的温度容易诱导材料脆性转变,劣化其摩擦学性能;相较于骤冷的冷却方式,自然冷却可以减小PTFE/PEEK复合材料内部由于冷却而产生的应力及其他结构缺陷,自然冷却条件下FDM成型试样的摩擦因数降低约16.81%,热压烧结试样摩擦因数降低11.65%,从而赋予材料更优的摩擦学性能。
Self-lubricating polytetrafluoroethylene/polyether ether ketone (PTFE/PEEK) composites for robot joint bearings were prepared by fused deposition modeling (FDM) process and hot-pressing sintering processes,and the materials were further modified by heat treatment.The effects of the various heat treatment stages (warming,holding and cooling) on the tribological properties of the materials were explored by single-factor test method.The experimental results showed that the heat treatment modification could significantly improve the tribological properties of PTFE/PEEK composites molded by FDM and hot-pressing sintering processes,but the temperature increase rate should be reasonably controlled,and too fast heating rate could easily lead to insufficient crystallization of the material and deteriorate the effect of the modification.The tribological properties of the specimens prepared at a heating rate of 2℃/min were optimal.The optimal holding temperature for FDM and hot-pressing sintered specimens were 210℃ and 205℃,respectively,and too high temperature was prone to induce brittle transformation of the material and deteriorate the tribological properties.Compared with the cooling method of quench cooling,the natural cooling could reduce the stress and other structural defects inside PTFE/PEEK materials due to cooling,which could reduce the friction factor of FDM molding specimens by about 16.81% and that of hot-pressing sintered specimens by 11.65%,endowing the materials with better tribological properties.
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基金资助
国家自然科学基金(61673385);2021年度北京市教育委员会科研计划项目(KM202110853002)
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