Wear-resistant effect PEEKS

The most studied anti-wear material modified by whiskers is PEEK. Wang et al." compared the performances of PEEK before and after modification with potassium titanate whiskers. The friction and wear performances of the latter showed obvious improvement over the former. Under 300 N, the wear resistance of the latter increases 2.64 and 2.11 times than the former, respectively. In addition, calcium carbonate whiskers have an excellent anti-friction effect on PEEK composite material. When the whisker content is less than 15%, the wear rate of the material decreases dramatically. The wear rate of the... 

Once the particle sizes are diminished down to the nanoscale (< 100 nm), the wear performance of these nanocomposites differs significantly from that of micron particle-filled systems. Polymers filled with nanoparticles are recently under discussion because of some excellent properties they have shown under various testing conditions. Some results were achieved in various studies, suggesting that this method is also promising for new processing routes of wear resistant materials. For instance, Xue et al. found that various kinds of SiC particles, i.e., nano, micron and whisker, could reduce the friction and wear when incorporated into a PEEK matrix at a constant filler content, e.g., 10 wt.% ( 4 vol.%). However, nanoparticles resulted in the most effective reduction. Nanoparticles were observed to be of help to the formation of a thin, uniform, and tenacious transfer film, which led to this improvement. The variation of Zr02 nanoparticles from 10 to 100 nm was conducted by Wang et al. The results showed a similar trend as most of the micron particles, i.e., the smaller the particles, the better was the wear resistance of the composites. 

Hybrid fiber composites do not only have favorable effects when considering mechanical properties. Friedrich and Jacobs examined the friction properties of GF-, CF-, and AF-reinforced EP, polyetheretherketone (PEEK), and polyamide (PA) matrix composites toward steel. The AF/CF hybrid composites showed the best wear resistance. 

It is worth noting that tribochemical reactions are not bound to result in positive effects on tribological performance. When PTFE powder and nano-SiC particles were jointly incorporated into PEEK, for instance, the friction reduction and wear resistance capacities of the nanocomposites became worse. The reason for this was the chemical reaction between the nanometer SiC and PTFE during the sliding friction process. The formation of SiFx by consuming a certain amount of nano-SiC and PTFE deteriorated the property of transfer film. Only when the content of PTFE was high enough, the ternary composites nano-SiC/PTFE/PEEK exhibit lower frictional coefficient than the binary ones PTFE/ PEEK. 

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