TENSILE STATIC FATIGUE OF 2D SIC SIC COMPOSITES WITH MULTILAYERED (PYC-SIC)(N) INTERPHASES AT HIGH-TEMPERATURES IN OXIDIZING ATMOSPHERE/

The pyrocarbon (PyC) interphase, which is commonly used to monitor the fibre/matrix interactions in SiC/SiC and C/SiC composites, generally oxidizes in air at high temperatures. This phenomenon alters the perfo rmances and the load-carrying capability. Recently, SiC/SiC composites with multilayered interphases have been developed. The interphase con sists of alternate sublayers of PyC and SiC deposited on the fibres by Chemical Vapour Infiltration. The composites exhibit mechanical prope rties (high strength, high toughness) and features (multiple crack def lection) that are interesting for high temperature applications. The m echanical behaviour and lifetime under tensile static loading (60-140 MPa) at high temperatures (700 degrees C-1200 degrees C) in air are re ported for a 2D SiC/SiC composite with a multilayered interphase invol ving 4 PyC/SiC sequences ((PyC-SiC)(4)). The lifetime of the composite with the multilayered interphase is significantly improved with respe ct to that of the composite with a homogeneous PyC interphase. (C) 199 8 Elsevier Science Ltd. All rights reserved.