Mechanical properties of SiCf/SiC mini-composites reinforcements for SiCf/SiC composites

摘要

SiC_f/SiC mini-composites with single-tow microstructures are typically used as reinforcing materials for larger composites and it is essential to obtain accurate mechanical properties for such mini-composites to understand the fundamental mechanical properties of larger composites. In this paper, the mechanical properties of SiC_f/SiC mini-composites fabricated through a precursor infiltration and pyrolysis process, as well as those of their constituents, are analysed. The Young's moduli, strengths, and ultimate strains of the SiCf/SiC mini-composites and SiC fibres are measured through uniaxial tensile tests. The experimental results reveal that the mechanical performance of the SiC fibres is diminished during the hightemperature manufacturing process. The effects of the PyC interface on the mechanical properties of the SiC fibres and SiC_f/SiC mini-composites are also explored. The results demonstrate that the influence of the PyC interface on the mechanical properties of the SiC fibres is negligible, but significantly increases the strength and failure strain of the SiC_f/SiC minicomposites. A nanoindentation test is employed to measure the Young's modulus of the SiC matrix. The relationship between the Young's moduli of the fibre, matrix, and mini-composite is theoretically characterised and can be reasonably explained by the theory of composite mechanics based on the microstructures of the mini-composites.