Evaluation of High-Temperature Water Oxidation Behavior of a 2D-SiC/SiC Composite in terms of In-plane Shear Fracture Properties

Abstract

In-plane shear properties of two-dimensional SiC-continuous-fiber reinforced SiC-matrix composite (2D-SiC/SiC) is studied by the modified Iosipescu shear test at elevated temperatures with water vapor environment. The proposed test geometry combines the advantage of Iosipescu pure shear test with a simple compressive loading which makes the test particularly suitable for high temperature testing. Finite element analysis confirms that proposed geometry introduces minor error in pure shear stress state in the gauge cross-section comparing to alternative geometries. A 2D-SiC/SiC composite was oxidized and measured the shear strength in argon/water vapor environment at temperatures between 1200˚ and 1600˚C. Humidity was varied between 0 and 30 %RH at a total pressure of 0.1 MPa and a constant gas velocity of 300 cm³/min. Influence of water vapor oxidation on some mechanical properties and morphological responses are described in terms of the in-plane shear strength, compliance, changes in sample weight and SEM images.