Mechanical properties of Cf/SiC-ZrB2 ceramic composites with bouligand structure prepared by low-temperature demolding combined with precursor infiltration and pyrolysis

A method combining low-temperature demolding with precursor infiltration and pyrolysis (PIP) for preparing Cf/ SiC-ZrB2 ceramic composites with bouligand structure is proposed. First, Cf/SiC-ZrB2-PCS ceramic films were prepared using polycarbosilane (PCS), carbon fiber, and SiC-ZrB2 ceramic particles through liquid nitrogen demolding technology. Then, Cf/SiC-ZrB2 green body with bouligand structure was achieved by helically assembled and pre-crosslinked Cf/SiC-ZrB2-PCS ceramic films at a fixed angle. Finally, precursor infiltration and pyrolysis method was employed to densify the Cf/SiC-ZrB2 ceramic composites with bouligand structure using PCS. The mechanical properties of the composites with different carbon fiber contents were investigated, revealing that at a carbon fiber content of 30 %, the composites exhibited a flexural strength of 358.9 MPa, a fracture toughness of 10.4 MPa center dot m1/2, and a work of fracture of 2445.4 J center dot m-2. The toughening mechanism of Cf/ SiC-ZrB2 ceramic composites with bouligand structure was elucidated through two-dimensional crack propagation analysis via scanning electron microscopy (SEM) with three-dimensional fracture network reconstruction using synchrotron X-ray computed tomography (CT).