Structure-property correlation in cellular silica processed through hydrophobized fused silica powder for aerospace application

Attempts have been made towards a novel process for the preparation of cellular silica with interconnected cells, tailored porosity and pore size distribution using a combination of hydrophobized fused silica powder and direct foaming methodology. The process has resulted into cellular silica tiles as large as 100 × 100 × 25 mm dimensions. The resulting ceramic foams sintered at 1100 °C, consisted of a highly interconnected network of spherical cells with densities as low as 10% of theoretical. The pore size distributions and cell size have been found in the range of 50-250 μm and ∼6-16 ppi, respectively. The microstructure has shown an open and interconnected porosity with an average permeability occurring in the region of ∼10−8 m2. The creation of highly densified cell walls and tortuous struts between the cells has led to foams with a comparatively high compressive strength and Young's modulus and with an excellent thermal shock properties.