In situ characterization of residual stress evolution during heat treatment of SiC/SiC ceramic matrix composites using high‐energy X‐ray diffraction
Abstract
Volumetric strains were measured in silicon carbide/silicon carbide melt‐infiltrated ceramic matrix composites (CMCs) at ambient and high temperatures using high‐energy synchrotron X‐ray diffraction (XRD). Both silicon and silicon carbide constituents were interrogated utilizing a broad spectrum of diffracting planes that would be largely inaccessible to common laboratory XRD equipment. Residual room‐temperature principal strains in the melt‐infiltrated silicon phase were found to be approximately 1100 με in compression, corresponding to stresses of approximately 300 MPa using simplifying constitutive assumptions. Residual room‐temperature principal strains in silicon carbide particles found throughout the matrix were approximately 500 με in tension, corresponding to approximately 300 MPa. Residual strains were found to decrease considerably as temperatures increased from ambient temperature to 1250°C. Residual strains returned to approximately preheat treatment values after cool‐down to ambient temperature. Strain measurements in the silicon phase were found to be significantly affected by dissolved boron dopant levels causing contraction of the silicon lattice. This contraction must be accounted for in high‐temperature experiments for accurate calculation of stresses in the silicon phase.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 06, 2020
- Source ID
- 10.1111/jace.17493
Entities
People
- Andrew J. Ritchey
- Craig Przybyla
- Jun‐sang Park
- Michael W. Knauf
- Paul A. Shade
- R. B. Pipes
- Rodney W. Trice
Organizations
- Air Force Research Laboratory
- Argonne National Laboratory
- Purdue University
- Rolls-Royce North America
- United States Air Force