Carbon Fiber‐Reinforced Silicon Carbide (C/C‐ <scp>SiC</scp> ) Fabrication Derived From Polyetherketoneketone ( <scp>PEKK</scp> ) as an Alternative Thermoplastic Carbon Precursor

ABSTRACT This study shows the first successful fabrication of a carbon fiber‐reinforced silicon carbide (C/C‐SiC) via the liquid silicon infiltration process using two thermoplastic polyetherketoneketone (PEKK) powders as carbon precursors. Samples are analyzed after each processing step and compared to polyetheretherketone (PEEK)‐derived reference samples. The carbon yield was above 65% for PEKK and 54% for PEEK, possibly due to the greater crosslinking potential of PEKK. Rheological measurements showed a higher melt viscosity of PEKK 60/40 (which consists of 60% terephtalic and 40% isophtalic moieties) than PEEK. The higher viscosity of PEKK 60/40 affected the carbon fiber‐reinforced plastic (CFRP) microstructure because it resulted in more matrix pores and some partly saturated fiber tows in the PEKK 60/40‐derived CFRP. The incomplete infiltration of fiber tows by PEKK in the CFRP state led to the undesirable reaction of the single carbon fibers during final siliconization. However, the effect was of minor influence, and the microstructure and phase composition remained unaffected. Mechanical testing of PEEK‐ and PEKK‐derived C/C‐SiC showed excellently comparable properties with a mean flexural strength above 200 MPa and a strain to failure above 0.55%. Thus, PEKK‐derived C/C‐SiC is a suitable alternative thermoplastic polymer for C/C‐SiC fabrication.