Strength retention of fire resistant aluminosilicate–carbon composites under wet–dry conditions

The results of an experimental investigation of the durability of inorganic matrix–carbon composites are reported. The matrix, which can sustain temperatures up to 1000°C, is being evaluated for applications that require fire resistance, such as the interior of aircraft. The original matrix formulation, which had a high ratio of silica to alumina, was found to weaken when subjected to wet–dry cycles. Preliminary tests indicated that an efficient way to increase water-stability was to increase the amount of alumina in the matrix. Therefore, a systematic evaluation was carried out to obtain the optimum silica/alumina ratio for improving stability of composites in water. In-plane shear strengths were used as an indicator of strength retention after the specimens were subjected to 50 wet–dry cycles. The results indicate that silica/alumina ratio between 18 and 20 provide the best results. In this range, strength loss is negligible.

This paper was originally published in Composites: Part B 31 (2000) Pages 107-111