SiOC glass modified by montmorillonite clay

The addition of inexpensive montmorillonite clay to a silicone resin employed as preceramic polymer was found to be advantageous for the production of SiOC glass matrix composites. Dense SiOC based monoliths were achieved with the addition of a substantial amount of calcined clay (30 wt.%) to the preceramic polymer; these composites exhibited remarkable hardness and fracture toughness, higher than those of SiOC glasses reported in the literature, due to the very small dimensions of silica and mullite crystal inclusions deriving from the decomposition of clay. Microcellular SiOC glass based microcellular foams were also produced, from composites filled by both calcined and organically functionalized clay. The inclusions from the decomposition of clay provided for the retention of the microcellular structure even after oxidation at 1200 and 1450 8C. Functionalized clay showed a more pronounced effect in limiting the extent of the densification and collapse of microcellular shape than calcined clay. In both cases, the crushing strength after oxidation was found to be particularly remarkable. # 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.