Microstructural and mechanical characteristics of SiC/SiC composites with modified-RS process

This paper deals with the efficiency of modified-reaction sintering techniq ues including a impregnation pressure and a cold pressure as well as the ap plicability of new high performance fiber, in order to develop high perform ance SiC/SiC composites. SiC/BN coated Hi-Nicalon fiber, SiC coated Tyranno ZMI fiber and Tyranno SA fiber were used in this composite system. Microst ructural characteristics of reaction sintered SiC/SiC composites were inves tigated by means of SEM, EDS and TEM. Mechanical properties and fracture me chanisms of SiC/SiC composites were also evaluated through the three-point bending test. Improved SiC/SiC composites with high density and high streng th were successfully fabricated by the sequential application of low pressu re impregnation and cold pressing processes. An excellent chemical stabilit y of Tyranno SA fiber during the reaction sintering process was also reveal ed. Tyranno SA fiber reinforced SiC/SiC composites with no interfacial coat ing exhibited good flexural strength and elastic modulus, compared to those reinforced by BN/SiC coated Hi-Nicalon and SiC coated Tyranno ZMI fibers. However, this composite system needed an appropriate interfacial coating fo r proper CMC composite behavior. (C) 2001 Elsevier Science B.V. All rights reserved.