Pressureless sintering of SiC-coated carbon nanofiber/SiC composites and their properties

抄録

In this study, in order to improve interfacial strength between CNFs and SiC matrix and to disperse CNFs uniformly in the SiC matrix, using the SiC-coated CNFs which were prepared using SiO₂ powder at 1400–1800°C in argon atmosphere, CNFs/SiC composites were fabricated in argon atmosphere under pressureless condition. The non-coated CNFs/SiC and SiC-coated CNFs/SiC composites reached near the full density at 2150°C. The SiC grains and the carbon agglomerates in the composites tended to be finer with an increase in amount of SiC coating on CNFs. The SiC-coated CNFs/SiC composites showed almost the same fracture toughness (4.5–5.0 MPa·m^0.5) with the non-coated CNFs/SiC composite. On the other hand, the SiC-coated CNFs/SiC composites showed higher bending strength than the non-coated CNFs/SiC composite, and the bending strength became higher with an increase in amount of SiC coating on CNFs. The maximum bending strength was 551 MPa, which represent a 32% increase compared with that of the non-coated CNFs/SiC composite.