A Potential Oxide/Oxide Ceramic Matrix Composite for Gas Turbine Applications

Abstract

WHIPOX® (Wound Highly Porous Oxide CMCs) are oxide/oxide composites which are composed of highly porous alumino silicate or alumina matrices and of alumino silicate (Nextel 720, 3M) or alumina (Nextel 610, 3M) fibers. The materials are fabricated by a computer-controlled winding technique, developed at DLR. After eventual forming and joining steps, the green prepegs are pressureless sintered in air at 1300°C. The high temperature behavior of the CMCs is mainly controlled by the thermo-mechanical properties of the oxide fibers. For long-term use (>10,000 h) an application limit for the composite of about 1100°C is expected. It can, however, be improved by external thermal barrier coatings up to a maximum surface temperature of 1300°C. Gas burner tests show that the composites are extremely resistant against thermal fatigue. Therefore it is a material with a high potential for the use under the long-term high temperature conditions of gas turbine engines.