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 lightweight and high temperature stability. CMCs possess high strength, and are being investigated for use in next-generation aircraft engines. CMCs show great promise for this application, but are subject to degradation from hot corrosion, a process in which atmospheric salts combine with engine exhaust, and can react with CMC materials at high temperatures. Hot corrosion may be a limiting factor in implementing CMCs in aircraft engines, and protection schemes are required. A thermally stable amorphous aluminum phosphate material was investigated in Phase I as a coating on non-oxide CMCs to promote resistance to hot corrosion. The coating material is a low cost, solution derived material which has a unique glass structure that is resistant to crystallization even at elevated temperatures, and has demonstrated resistance to sodium sulfate at elevated temperatures. In this Phase II project, ATFI will work with our industrial partners to build on Phase I results with the objective to develop a prototype part and explore preliminary considerations for technology transition. Effectiveness at reducing damage from hot corrosion as well as impact on mechanical properties of the CMC will be studied.