High-temperature CMC Processing for Ceramic-to-Ceramic Joining and for Interlaminar Strength Evaluation

There is a strong need to develop and demonstrate inter-laminar tension test methods for CMC at high temperatures in NAVY JSF Program for aero-engine components. MATECH GSM (MG) proposes to address this need by employing a variety of innovative low-cost pre-ceramic polymer-derived high temperature CMC adhesives between CMC test coupons and push rods. MG’s high-temperature CMC adhesives are designed to facilitate ceramic-to-ceramic joining for the purpose of evaluating high temperature interlaminar strengths. Traditionally, joining adhesives are mainly developed for bonding two dissimilar materials; hence its structural performances, particularly off-axis behaviors accompanied by a necessity of non-brittle failure are mostly neglected. The CMC adhesives proposed here is a ceramic matrix composite that demonstrates graceful failure but is stronger than that of the test-coupons. Due to the two already existing given materials of the test-coupon and fixture, the newly added third material must be as physically close as possible to the other two materials from the beginning. The PIP CMC processing is only one densification method among several ceramic matrix formation routes that meet this first requirement. It is low-cost, a variety of active/non-active fillers can easily be added, and it is capable of forming shapes at low temperatures.