A report presents updated information on the developments described in "MoSi2-Based Composite Materials for Aircraft Engines" (LEW-16617),NASA Tech Briefs, Vol. 22, No. 9 (September 1998), page 62. To recapitulate: Hybrid composites of (1) SiC-based fibers within (2) matrices that are, themselves, composites of MoSi2 containing 30 to 50 volume percent of Si3N4particles are candidate high-temperature-resistant materials for use in advanced aircraft engines. The addition of the Si3N4 particles (1) results in the formation of an Si2ON2 protective scale that increases resistance to low-temperature accelerated oxidation, which otherwise causes catastrophic "pest failure" of MoSi2; (2) increases high-temperature creep strength to almost 105 times that of neat MoSi2; (3) doubles room-temperature toughness; and (4) decreases the coefficient of thermal expansion to such an extent as to eliminate matrix cracking in the presence of SiC-based fiber reinforcement, even after thermal cycling.

This work was done by Mohan G. Hebsur of Ohio Aerospace Institute for Glenn Research Center.

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center
Commercial Technology Office
Attn: Steve Fedor
Mail Stop 4 - 8
21000 Brookpark Road
Ohio 44135

Refer to LEW-16884