Refractory Open-Cell Foams: Carbon, Ceramic, and Metal

Foam-core sandwich panels offer exceptional stiffness-to-weight ratios, and Ultramet has used this architecture for advanced mirror systems. Foam-core mirrors employ an optical faceplate that is attached to the surface of a foam billet, and, if stiffness requirements demand, a second faceplate can be added to the rear surface. Mirrors have been fabricated with both flat and curved optical surfaces, and several material systems have been used. Silicon and silicon carbide systems offer the greatest stiffness-to-weight ratio.