High-Temperature Amorphous Coating for CMCs for Protection against Hot Corrosion

Ceramic matrix composites (CMCs) are being targeted for many military and commercial applications due to their light weight and high temperature stability. Their deployment is hampered by limited environmental durability. The Navy, under the JSF program, is evaluating a high performance CMC for an exhaust nozzle component. The CMC suffers from environmental degradation, primarily due to hot corrosion from salt ingestion. Severe thermal gradients imposed on the part, along with thermal cycling and fatigue effects, may cause matrix microcracking which exacerbates corrosion. Based on a new high-temperature stable amorphous coating material and low-cost and easy-to-apply solution-based process, ATFI proposes a study to solve this problem. The material's protection against molten salt and high temperature steam and compatibility with many metal and ceramic materials has been demonstrated over the temperature range of interest. Phase I will demonstrate its effectiveness by environmental exposure tests and high temperature anneals. If Phase I is successful, the technology can be transitioned rapidly due to the simplicity of the approach and the minimal capital equipment necessary. Phase II work will extend the concept to optimize coating formulation, application expertise, and demonstration of coating larger panels with the objective of transitioning the technology to the JSF program.