HIGH TEMPERATURE LIQUID FILM OXYGEN BARRIER

THE USE OF A LIQUID METAL FILM IS PROPOSED AS A BARRIER FOR PREVENTING ACCESS OF OXYGEN TO CARBON-CARBON COMPOSITES AT TEMPERATURES TO 4500 DEG F. THE LIQUID FILM IS COMPRISED OF A NOBLE METAL, INSOLUBLE IN A POROUS TUNGSTEN LAYER PREVIOUSLY APPLIED AS AN EROSION RESISTANT LAYER. AN IRRIDIUM LAYER COMPRISES THE MEANS OF PROTECTING THE TUNGSTEN LAYER FROM CARBIDING REACTIONS WITH THE SUBSTRATE. PRELIMINARY SCREENING TESTS WILL BE BASED ON USE OF AN OXHYDROGEN TORCH AND PHYSICAL CHANGES IN THE SUBSTRATE AFTER EXPOSURE. VARIATIONS IN COMPOSITION OF THE LIQUIDUS TEMPERATURE. THE INFLUENCE OF SUBSTRATE STRUCTURE AND COMPOSITION WILL BE EXAMINED BY USING CARBON AND GRAPHITE BASED MATERIALS OF VARYING POROSITY. OBSERVATIONS AND MEASUREMENTS MADE WILL SERVE TO ESTABLISH A BASE FOR PROJECTING THE VIABILITY AND PRACTICALITY OF THIS APPROACH AND RECOMMENDATIONS FOR FUTURE WORK WILL BE PROVIDED.