An effective growth of hierarchical BNNTs/SiC fibers with enhanced interfacial properties

Abstract Tailoring the SiC fiber-matrix interface in micron-sized fibers is crucial to attaining enhanced mechanical properties in ceramic reinforced composites. Herein, the authors report the growth of boron nitride nanotubes (BNNT) onto SiC fibers (SiCf), creating a fuzzy fiber architecture to promote the surface area for a defined load path of fiber to the matrix and improve the mechanical properties of these structures. Successful BNNT-growth is achieved by a boron oxide chemical vapor deposition method combined with growth vapor trapping with optimum parameters of 1200 °C and 1 h, comparatively low temperature to those reported in the literature. The strength loss of SiCf after exposure to 1200 °C was attributed to high process temperature, similar to what has been observed in the literature. Hence, BNNT growth does not lead to additional strength loss on these fibers measured by a single fiber tensile test. Moreover, through this direct growth method, grown BNNTs utilize a surface-anchored BNNTs/SiCf, creating a good matrix adhesion to prevent fiber-fiber sliding and pullout and increasing the interfacial shear strength (IFSS) with epoxy. Furthermore, microbond tests show that fuzzy BNNTs/SiCf architecture increased IFSS by at least 87.8% compared to as-received SiCf.