Ultralow Wear Self-Mated PTFE Composites
Ultralow Wear Self-Mated PTFE Composites
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DOI：
10.1021/acs.macromol.1c02581
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发表时间：
2022-05
期刊：
影响因子：
5.5
通讯作者：
Kylie E. Van Meter;C. Junk;Kasey L. Campbell;T. Babuska;B. Krick
中科院分区：
文献类型：
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作者：
Kylie E. Van Meter;C. Junk;Kasey L. Campbell;T. Babuska;B. Krick
在PTFE-PEEK和聚四氟乙烯(PTFE)-α-氧化铝复合材料中观察到非常低的磨损率，当在“自配对”配置中，聚合物销滑动到相同组成的聚合物反样品上时。每种复合材料都在受控湿度的环境中在线性往复摩擦试验机上对两种不同的配对样品进行测试：用于比较的聚合物配对样品和不锈钢配对样品。对于所有自配对的PTFE-PEEK复合材料[聚醚醚酮(PEEK)wt%10、20、30、40和50]，与不锈钢相比，平均摩擦系数降低，稳态磨损率和总磨损率提高。自配对聚四氟乙烯-聚醚醚酮(wt%10-40)获得了10-9mm3/Nm量级的超低磨损率和0.08-0.14的摩擦系数。滑动表面的红外光谱表明，与不锈钢滑动的样品相比，自匹配的PTFE-PEEK复合材料在滑动界面上积累了更多的PEEK，并表达了更多的摩擦化学羧酸盐物种，这与超低磨损PTFE材料有关。聚四氟乙烯复合材料在钢上滑动时，依靠转移膜的形成来获得超低的磨损性能。这是通过单向增加从聚合物销到钢衬底的表面能梯度来实现的，它主导着钢上滑动的聚四氟乙烯复合材料的传输和磨损。然而，自配对的超低磨损聚四氟乙烯基复合材料只依赖于摩擦膜的形成和稳定性，摩擦膜由摩擦化学改变的聚四氟乙烯和新的羧酸盐端基以及累积的填料(即聚醚醚酮或氧化铝)组成。这些薄膜具有自我调节功能，表面能差异很小。这些低能表面的紧密匹配有助于低摩擦和超低磨损。自配对的聚醚醚酮填充聚四氟乙烯的性能优于氧化铝填充聚四氟乙烯，主要是因为聚醚醚酮容易在表面聚集。此外，聚合物共混物的表面增强和锚定比颗粒增强复合材料更好。
Remarkably low wear rates were observed in PTFE–PEEK and polytetrafluoroethylene (PTFE)-alpha-alumina composites when evaluated in a “self-mated” configuration, where a polymer pin is slid against a polymer countersample of the same composition. Each composite was tested in a controlled humidity environment on a linearly reciprocating tribometer on two different countersamples: a polymer countersample (self-mated) and a stainless steel countersample for comparison. For all the self-mated PTFE–PEEK composites [polyether ether ketone (PEEK) wt % 10, 20, 30, 40, and 50], the average friction coefficient was reduced, and the steady-state and total specific wear rates were improved when compared to testing against stainless steel. Self-mated PTFE–PEEK (wt % 10–40) achieved ultralow wear rates on the order of 10–9mm3/Nm and friction coefficients of 0.08–0.14. When compared with samples slid against stainless steel, IR spectroscopy of the sliding surface showed that the self-mated PTFE–PEEK composites accumulate more PEEK at the sliding interface and more expression of a tribochemical carboxylate species, which have been linked with ultralow wear PTFE materials. The PTFE composites slid on steel rely on the formation of transfer films for ultralow wear performance. This is achieved by unidirectional increasing surface energy gradients from the polymer pin to the steel substrate, which dominate the transport and wear of PTFE composites slid on steel. However, the self-mated ultralow wear PTFE-based composites rely only on the formation and stability of tribofilms that consist of tribochemically altered PTFE with new carboxylate end groups as well as accumulated filler (i.e., PEEK or alumina). These films have self-regulating, minimal differences in surface energy. The close match of these low-energy surfaces contributes to low friction and ultralow wear. The self-mated PEEK-filled PTFE outperforms the alumina-filled PTFE primarily because of the ease at which PEEK accumulates at the surface. Additionally, the reinforcement and anchoring of the surface is better for a polymer blend than a particle-reinforced composite.