Preparation of SiC fiber-reinforced SiC composites

In this paper, Hi-Nicalon/SiC composites were prepared by precursor pyrolysis-hot pressing (PP-HP) and precursor impregnation-pyrolysis (PIP), respectively, and the effect of preparation processes on the microstructure and mechanical properties of the composites was investigated. It was found that the composite prepared by PP-HP exhibited a brittle fracture behavior, which was mainly ascribed to a strongly bonded fiber/matrix interface and the degradation of the fibers caused by a higher processing temperature. On the contrary, the composite prepared by PIP showed a tough fracture behavior, which could be rationalized on the basis of a weakly bonded fiber/matrix interface as well as a higher strength retention of the fibers. Therefore, compared with the composite prepared by PP-HP, the composite prepared by PIP achieved much better mechanical properties of 703.6 MPa in flexural strength and 23.1 MPa m(1/2) in fracture toughness. The results also showed that PIP process, in comparison with PP-HP process, was more suitable for preparation of Hi-Nicalon/SiC composites. (C) 2003 Elsevier B.V. All rights reserved.