Dry Powder Processing of Fibrous Fumed Silica Compacts for Thermal Insulation

This study proposes a new dry powder processing method to produce fiber reinforced fumed silica compacts for highly efficient thermal insulation. First, mechanical forces such as shear stress and compression were applied into a fumed silica powder (BET SSA 300 m²/g) and glass fibers (3 mm length, 11 μm diameter) using an attrition type milling apparatus without any media balls. In the resultant powder mixture, fumed silica porously coated glass fiber composites were successfully prepared. SiC particles were also integrated as opacifiers. Then, the fibrous fumed silica porous compact was formed by dry pressing of the powder mixture and exhibited fracture strength of 1.58 MPa at room temperature and thermal conductivity of 0.0282 W/mK at 400°C, when its porosity was 80.1%.