INVESTIGATION OF HIGH TEMPERATURE RESISTANT MATERIALS

X-ray diffraction analysis showed the absence of cristobalite in ethyl-silicate-40-impregnated samples. The effect of multiple impregnation on the strength of fused silica test bars impregnated with 10, 30, 50% solutions of AlCl3.6H2O was studied. Samples impregnated with the 10% solution cracked in cooling after the second refiring cycle; the strength of slipcast fused silica was reduced from 3750 to 730 psi after the first impregnating and refiring cycle. A decrease in strength and an increase in cristobalite content were also exhibited by samples impregnated with 30 and 50% AlCl3.6H2O. A revised vacuum-pressure technique of impregnating slip-cast fused silica was studied. The study of flame glazing was continued. An IR quartz tube furnace was constructed to control annealing temperatures of glazed samples; the fused silica samples were successfully glazed by annealing but cracked upon cooling.