Microstructure and mechanical properties of 3D Cf/SiBCN composites fabricated by polymer infiltration and pyrolysis

Bowen Chen,Dewei Ni,Qi Ding,Shaoming Dong,Yusheng Ding,Xiangyu Zhang,Hongda Wang

doi:10.1007/s40145-020-0414-5

Abstract

In this work, three-dimensional (3D) Cf/SiBCN composites were fabricated by polymer infiltration and pyrolysis (PIP) with poly(methylvinyl)borosilazane as SiBCN precursor. The 3D microstructure evolution process of the composites was investigated by an advanced X-ray computed tomography (XCT). The effect of dicumyl peroxide (DCP) initiator addition on the crosslinking process, microstructure evolution, and mechanical properties of the composites were uncovered. With the addition of a DCP initiator, the liquid precursor can cross-linking to solid-state at 120 °C. Moreover, DCP addition decreases the release of small molecule gas during pyrolysis, leading to an improved ceramic yield 4.67 times higher than that without DCP addition. After 7 PIP cycles, density and open porosity of the final Cf/SiBCN composite with DCP addition are 1.73 g·cm−3 and ∼10%, respectively, which are 143.0% higher and 30.3% lower compared with the composites without DCP addition. As a result, the flexural strength and elastic modulus of Cf/SiBCN composites with DCP addition (371 MPa and 31 GPa) are 1.74 and 1.60 times higher than that without DCP addition (213 MPa and 19.4 GPa), respectively.

Highlights

Siliconboron carbonitride (SiBCN) ceramics haveJ Adv Ceram 2021, 10(1): 28–38 thermal shock resistance restrict the wide application of SiBCN ceramics [8,9]
To determine the effect of dicumyl peroxide (DCP) initiator on PBSZ precursor, both precursors with (PBSZ-D) and without DCP (PBSZ) were heat-treated at 120 °C for 2 h, which are labeled as PBSZ-D-120 and PBSZ-120, respectively
It should be noted that the precursor with DCP cross-links to a solid-state after heat-treatment at 120 °C for 2 h, but the precursor without DCP still presents as a liquid state (Fig. 2)

Summary

Introduction

Siliconboron carbonitride (SiBCN) ceramics haveJ Adv Ceram 2021, 10(1): 28–38 thermal shock resistance restrict the wide application of SiBCN ceramics [8,9]. A large amount of small-molecule gas is released during the pyrolysis process, which reduces the ceramic yield of precursor and decreases the fabrication efficiency of the composites [27,28,29]. Using the PBSZ precursor with and without DCP addition, the SiBCN matrix was introduced into the 3D carbon fiber fabrics by vacuum impregnation, followed by cross-linking at 120 °C for 2 h.

Results

Conclusion