Two thermoplastic matrices, polyetheretherketone (PEEK) and polyetherimide (PEI), are examined in this work in terms of their suitability as carbon precursors for C/C‐SiC composites. The carbon fibers are pretreated between 400 and 1600 °C in nitrogen atmosphere to modify the surface functionality, which was characterized with XPS. An analysis of the C/C‐SiC composition shows an increasing SiC content as a function of the increased fiber pretreatment temperature and the polymer precursor. Bending tests of C/C‐SiC composites exhibit enhanced fiber‐pull‐out effects at a fiber pretreatment temperatures from 400 to 800 °C.
An experimental investigation was performed to study the influence of fatigue damage introduced by different loading cycles on the residual tensile strength (RTS) of plainweave reinforced C f /C-SiC composites (2D C/C-SiC). The specimens were subjected to the fatigue stress of 57 MPa for the preselected numbers of cycles as follows: 10 2 , 10 4 and 10 5 , respectively, before the static tensile test. The microstructures and fractured surfaces after the tensile test were examined by optical and scanning electron microscopy, respectively. The results showed that the RTS of the specimens after the preselected fatigue cycles numbers of 10 2 , 10 4 and 10 5 increase to 89.8, 94.1 and 82.4 MPa, respectively, which are somewhat higher compared to the virgin samples (79.7 MPa).Additionally, we found that the linear part of the tensile stress-strain curve is independent on the fatigue cycles. Finally, the increased fatigue damage in C/C-SiC composites could determine a reduction of elastic modulus in all cases of fatigue tests.
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