Graphite-PEEK composites

Bucher, R.A, and Hinkley, J.A. (1992). Fiber/matrix adhesion in graphite/peek composites. J. Thermoplastic Composite Mater. 5, 2-13. 

As you can see, bone is a very complex composite material and, as snch, is difficult to artificially replicate. Nonetheless, there are a nnmber of materials of all types that are being nsed as bone replacements. Polymethylmethacrylate (PMMA), titaninm, graphite/polyethyletherketone (PEEK) composites, and tricalcinm phosphate, among... 

In the following example, scanning acoustic microscopy is combined with optical microscopy to measure intimate contact at the ply interfaces of a [0o/90o/0°]r graphite-PEEK laminate. First, eight holes, 1.5 mm (0.059 in.) in diameter, were drilled into the composite specimen. These holes, shown in Figure 7.12, were used to locate where on the composite specimen the scanning acoustic microscope images were taken. 

In order to compare the tribological performance of HP-LCP composite with two reference materials, i.e. a PI composite containing PTFE and graphite, and a PEEK composite with PTFE and short carbon fibers, all composites were tested under the same sliding conditions. The PEEK composite was conditioned at 240 °C for 3 h before the sliding test. Table 2.2 shows the fi iction and wear properties of HP-LCP, PEEK and PI composite under a pressure of 1 MPa and a sliding speed of 1 m/s. One test was conducted at a room temperature of 23 °C, the other at controlled counterpart surface temperature of 190 °C. 

All these factors make it difficult to develop a cost effective solution for the separator plates. Initial trials were with graphite polymer molded composites. The polymers that were tried includes polyvinylidenefluoride (PVDF), polyetheretherketone (PEEK), perfluoroalkoxy (PEA) etc. Although most of the graphite polymer composite passed the 200°C phosphoric acid test, few survived more than few thousand hours, when they are maintained in 200°C phosphoric acid with a potential of 1.0 V w.r.t. SHE. Of the various polymers, PFA was found to be the most suitable. However, it was observed that after long exposure to PAFC temperature, the polymers got relaxed, causing an increase in the plate electrical resistance and porosity. However, all these plates exhibited excellent gas crossover resistance at least in the initial phase. 

Yoon TH, McGrath JE (1992) Enhanced adhesive performance of thermoplastic po-ly(imide siloxane) segmented copolymer with peek-graphite composites by gas plasma treatment. High Perform Polym 4(4) 203... 

Yoon TH (1991)AdhesionstudyofthermoplasticpolyimidesandTi-6Ai-4v allow and peek-graphite composites. PhD thesis, Virginia Polytechnic Institute and State University, Blacksburg... 

Yoon TH, McGrath JE (1991) Effect of surface preparation and thermoplastic ahesive structure on the adhesion behavior of peek-graphite composites. Mater Res Soc Symp Proc 190 (Plasma Process Synth Mater) 3 137-142... 

PEEK LCP (Ekonol) M0S2/ graphite Ekonol addition to PEEK/MoS2-graphite composites lowed wear rate and coefficient of friction 1171... 

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