Preparation and Characterization of Silica-Fiber / Aeroger Composite Heat Insulations

This research aims to find the optimum process for preparing a superior sandwich heat insulation by stacking silica-fiber mats and silica-aerogel core layer. Its typical application is assumed to be a thermal expansion mat for automotive catalytic converters. Two different preparation processes are examined in this study; one adopts a wet fabrication process for the silica-aerogel core layer and the other uses a dry process in which silica short fibers are pre-cured with silica-aerogels as the core layer. As the silica-fiber has a characteristic to generate condensation reaction forming Q4 silica structures when heated above 300°C, the composite heat insulation can be hot-molded to gain rigid structures including curved surfaces; it makes a suitable material as the thermal expansion mat for catalytic converters. The characterization of the sandwich heat insulation reveals that the increase of aerogel core layer significantly contributes to the heat insulation performance. The composition of SiC layer in the aerogel core layer is also important; it needs to be concentrated near the heated side in the core layer to prevent heat radiation. The molding flexibility of the composite heat insulation is also proved to produce circumferential heat insulation for catalytic converters for automotive applications.