Assessment of strength limiting flaws in ceramic heat exchanger components. Final report, September 1984--June 1993

The ability to predict energy efficient lifetimes for ceramic heat exchanger components is necessary for their design, manufacture, and sale. The ability to inspect components for critical defects and adherence to specifications is also vital. This is the final report of a three phase program. In phase 1, various nondestructive evaluation methods were evaluated for use on siliconized silicon carbide heat exchanger tubes. The more promising ones were further developed for use in phase 2. These methods were used to examine samples used in a mechanical testing program, carried out at room temperature and at high temperature, to determine the detectability of defects and the effects of load at high temperature. A model was developed for fast fracture reliability. During phase 3, the equipment installed during phase 2 was modified for faster, easier ultrasonic scanning and microfocus X-ray computed tomography. This report describes the methods used to improve ultrasonic scanning of tubes, to reduce artifacts and enhance defect detection by X-ray computed tomography, to carry out pressure tests and high temperature C-ring tests with acoustic emission monitoring, and to generate a lifetime prediction model. The final model, the verification test results, and a general procedure for establishing specifications and acceptance tests for ceramics are presented