Electrical Resistance as a Nondestructive Evaluation Technique for SiC/SiC Ceramic Matrix Composites Under Creep‐Rupture Loading

Abstract

SiC/SiC ceramic matrix composites under creep-rupture loading accumulate damage by means of local matrix cracks that typically form near a stress concentration, such as a 901 fiber tow or a large matrix pore, and grow over time. Such damage is difficult to detect through conventional techniques. This study demonstrates that electrical resistance is a viable method of monitoring and inspecting damage in SiC/SiC composites at high temperature. Both interrupted and uninterrupted creeprupture experiments were performed at 13151C and 110 MPa with in situ resistance measurements. A linear relationship was found between resistance and cumulative crack depth.Ã Specimen did not break.w Thermal mechanical fatigue (unloaded and cooled to room temperature at 1 and 5 h).z Inadvertent overload to 160 MPa while cooling.

Quantification of Foreign Object Damage and Electrical Resistivity for Ceramic Matrix Composites and Tensile Residual Strength Prediction

“…In addition, ER appears to be another technique with promise to ward characterizing damage in SiC/SiC systems [2,6], Since both the fibers and the matrix are semiconducting, if damage occurs in either constituent, the electrical circuit (properties) of the composite is altered, typically resulting in increased resistivity. This has been dem onstrated at room temperature during tensile tests of different fibertype CVI matrix composite [6] and at elevated temperatures during 1315 °C stress-rupture tests of CVI composites [2].…”

“…This has been dem onstrated at room temperature during tensile tests of different fibertype CVI matrix composite [6] and at elevated temperatures during 1315 °C stress-rupture tests of CVI composites [2]. Some additional work has been performed on melt-infiltrated composites [3],…”

“…Coupled with this is the need to develop adequate health monitoring techniques, which can be effectively correlated to the damage phenomena of interest in order to feed and/or corroborate life-modeling endeavors. Toward this aim, AE has proven useful at characterizing the primary damage phenomena [2,3] for these Contributed types of composites, which enable thermochemical-mechanical degradation mechanisms to proceed, i.e., matrix cracks whether micro or macro in nature [4,5].…”

Stochastic Virtual Tests for High-Temperature Ceramic Matrix Composites

“…Such measurements include those via optical microscopy (108)(109)(110)(111)(112)(113), scanning electron microscopy (114-119), speckle interferometry (120)(121)(122), acoustic waves (123)(124)(125), and electrical resistance (126,127). Most of these measurements were at room temperature; only a few studies tackled in situ measurements at high temperatures (e.g., References 114 and 128).…”

Detecting cracks in ceramic matrix composites by electrical resistance

“…Therefore, both matrix cracking and fiber breaks will influence the electrical properties. Previous work with chemical vapor infiltrated (CVI) SiC/SiC composites has shown a direct relationship between matrix crack density and resistance change for samples subjected to creep conditions 22 . Room temperature monotonic tensile tests have also been conducted concerning this material 23 .…”