REPAIR OF CERAMIC MATRIX COMPOSITES FOR EXHAUST WASHED AIRFRAME STRUCTURES

Nicalon/Blackglas CMC blastshields have been designed, fabricated, and tested for the AV-8B Harrier. They replace existing stainless steel blastshields that must be constantly repaired due to high thermal stresses and severe thermal acoustic loads. The improved CMC blastshields, however, cannot be introduced into the fleet until repair procedures have been developed and demonstrated for the CMC blastshield. The proposed program seeks to develop those repair procedures by combining the expertise of two leading organizations in this field. Materials Research & Design recently completed the first DOD program in repair of ceramic composites by successfully designing and demonstrating bonded, bolted, and reimpregnation repairs. Northrop-Grumman is the leading fabricator of Nicalon/Blackglas composites and they recently flight-tested the AV-8B blastshield that is the focus of this effort. The proposed Phase I program includes design, fabrication, and testing of repairs on Nicalon/Blackglas flat plates. A successful Phase I effort will provide a foundation for the Phase II effort which will address hat stiffened structures representative of the actual blastshield and thermoacoustic testing to simulate the in-service environment.