Influence of SiC Fiber Dispersion on the Mechanical Strength of SiCf/SiC Composites

The present study examines the influence of fiber dispersion on the internal structure and mechanical strength of SiCf/SiC composites fabricated utilizing spread SiC fibers. The fiber volume ratio of specimens incorporating spread SiC fibers decreased by 9 percentage points compared to those without spreading, resulting in smoother impregnation of resin slurry between fibers and, consequently, minimizing matrix porosity. To assess and compare the fiber dispersion in each specimen, a method was proposed for quantifying and evaluating the separation distance between fibers in composite materials. The results revealed a 2.23μm increase in the distance between fibers in the spread specimen relative to the non-spread specimen, corresponding to a notable 42.6% increase in the distance between fiber surfaces. Moreover, a 3-point flexural test showcased a 49.3% higher strength in the spread specimen, coupled with a more uniformly distributed deviation in test data. These findings underscore the substantial impact of SiC fiber dispersion on achieving uniform densification of the SiCf/SiC matrix and enhancing mechanical strength.