Study of SiC fiber axial compressive behavior using tensile recoil measurement

SiC fibers have been widely investigated as reinforcements for advanced ceramic matrix composites owing to their excellent high-temperature properties. However, the axial compressive strength of SiC fibers has not been thoroughly studied. In this study, the compressive behavior of two SiC fiber types containing different compositions and thermal degradation were characterized by tensile recoil measurements. Results illustrated that the SiC fiber compressive strength was 30%-50% of its tensile strength, after heat treatment at 1200celcius-1800celcius for 0.5 h in argon. The fiber compressive failure mechanism was studied, and a shear-bending-cleavage model was proposed for the recoil compression fracture of pristine SiC fibers. The average compressive and tensile strengths of the pristine SiC-II fiber were 1.37 and 3.08 GPa, respectively. After treatment at 1800celcius for 0.5 h in argon, the SiC-II fiber compressive strength decreased to 0.42 GPa, whereas the tensile strength reduced to 1.47 GPa. The mechanical properties of the fibers degraded after high-temperature treatment. This could be attributed to SiC grain coarsening and SiCxOy phase decomposition.

Automated summary

SiC fibers are widely studied as reinforcements for advanced ceramic matrix composites due to their excellent high-temperature properties. The compressive behavior of two types of SiC fibers with different compositions and thermal degradation was characterized in this study. It was found that the compressive strength of SiC fibers decreased after high-temperature treatment, attributed to SiC grain coarsening and SiCxOy phase decomposition.