LIGHT WEIGHT ALUMINA/ALUMINOSILICATE THERMAL PROTECTION MATERIALS

FUTURE ATMOSPHERIC ENTRY VEHICLES WILL REQUIRE MORE DURABLE,LIGHTER, REUSABLE THERMAL PROTECTION TO WITHSTAND TEMPERATURE AROUND 1370 K. STANDARD ALUMINA OR ALUMINOSILICATE REFRACTORIES HAVE LOW THERMAL CONDUCTIVITY AND RETAIN STRUCTURAL INTEGRITY AT THIS TEMPERATURE. MERIX CORPORATION PROPOSES AN INNOVATIVE METHOD TO PRODUCE A HIGHLY POROUS ALUMINA/ALUMINOSILICATE. THE POROUS STRUCTURE IS OF LOW DENSITY, HAS LOWER THERMAL CONDUCTIVITY THAN CORRESPONDING NON-POROUS MATERIALS AND WILL PROVIDE THENECESSARY THERMAL PROTECTION WITH REDUCED WEIGHT. IN ADDITION, IMPROVED THERMAL SHOCK RESISTANCE, AND RESISTANCE TO CRACK PROPOGATION UPON IMPACT BY HIGH VELOCITY PARTICULATE MATTER, ARE ADVANTAGES OFFERED BY THE PROPOSED MATERIALS. LOAD-BEARING CAPABILITY OF THE POROUS STRUCTURE MAY BE IMPROVED IF NECESSARY BY INCORPORATION OF CERAMIC FIBERS INTO THE CERAMIC DURING MANUFACTURE. MERIX WILL PRODUCE SAMPLES OF THE PROPOSED MATERIAL IN PHASE I OF THE PROJECT USING AN ADAPTATION OF THE SOL-GEL PROCESS FOR PRODUCING MONOLITHIC CERAMICS FROM POLYMERIC PRECURSORS. THESE SAMPLES WILL BE THOROUGHLY EVALUATED FOR MECHANICAL AND THERMAL PROPERTIES, TO DETERMINE THEIR SUITABILITY IN THERMAL PROTECTION APPLICATIONS. SOME SAMPLES WILL BE PRODUCED CONTAINING CERAMIC FIBERS AND EVALUATED FOR IMPROVEMENTS IN STRENGTH CHARACTERISTICS. THE MATERIAL SHOULD ALSO HAVE COMMERCIAL APPLICATION AS A SUPERIOR HIGH TEMPERATURE INSULATING MATERIAL FOR KILNS AND FURNACES AND MAY HAVE APPLICATION FOR ADVANCED POWER GENERATION (E.G MHD AND FUSION POWER). THE PROPOSED PROJECT APPEARS TO HAVE COMMERCIAL APPLICATION WHERE SUPERIOR HIGH TEMPERATURE INSULATING MATERIALS ARE REQUIRED AS, FOR EXAMPLE, IN HIGH PERFORMANCE KILNS AND FURNACES. IT MAY WELL ALSO HAVE APPLICATION TO HIGH TEMPERATURE ADVANCED POWER GENERATION SYSTEMS SUCH AS MHD AND FUSION.