Light weight silica tiles through foam casting method

Abstract

The possibility of making porous silica tiles starting from inexpensive fused silica powder using a direct foaming process has been examined. Aqueous slurry of silica with appropriate surfactants and binders have been allowed to foam by entraining air, following which it was cast, dried, and subsequently sintered at 1100 °C. The role of slurry composition and foaming duration, on the green and final density of foams has been studied. Silica foams with density as low as 11% of the theoretical density, and containing interconnected, primarily spherical pores with average size in the range of 50–2000 μm have been fabricated. The porous silica with densities between 18% and 62% of the theoretical value, have shown Young's modulus and compressive strengths in the range of 120–380 MPa and 0.5–3.3 MPa, respectively. A surface densification process, that can seal off the surface pores and provide a smooth exterior to the tiles, has also been established.