Fabrication method and mechanical properties of biomimetic Cf/ZrB2-SiC ceramic composites with bouligand structures

Abstract

Herein, biomimetic Cf/ZrB2-SiC ceramic composites with bouligand structures are fabricated by combining precursor impregnation, coating, helical assembly and hot-pressing sintering. First, Cf/ZrB2-SiC ceramic films are achieved through a precursor impregnation method using polycarbosilane (PCS). Second, the PCS-Cf/ZrB2-SiC ceramic films are coated with ZrB2 and SiC ceramic layers. Finally, hot-pressing sintering is employed to densify helical assembly Cf/ceramic films with a fixed angle of 30°. The microstructures and carbon fiber content on the mechanical properties of biomimetic Cf/ZrB2-SiC ceramic composites are analyzed in detail. The results show that the coated ceramic layer on PCS-Cf/ZrB2-SiC films can heal the cracks formed by pyrolysis of PCS, and the mechanical properties are obviously improved. Meanwhile, the mechanical properties could be tuned by the contents of the carbon fiber. The toughening mechanisms of Cf/ZrB2-SiC ceramic composites with bouligand structures are mainly zigzag cracks, crack deflection, multiple cracks, carbon fiber pulling out and bridging.