Processing Methods for High Reliability Silicon Nitride Heat Engine Components

The paper discusses highlights of a silicon nitride processing methodology that has been developed in the course of a major four-year DoE funded program in processing for reliability. The program focused on the attainment of high strength and reliability through the identification and subsequent control of strength-degrading flaws introduced during processing unit operations. Process control and NDE methods applied to achieve an optimized process with the potential to produce high-reliability advanced heat engine components are discussed. Concluding remarks are directed to the extensive tensile strength database that has been generated through testing of over 300 tensile rods produced by the optimized process.