Si-O-C Aerogels as Casting Additives

Abstract

Aerogels are nanostructured open porous materials produced via sol-gel process. At the foundry industry they restrain many typical cast defects. Many defects are known to appear on account of the thermal, mechanical and/or chemical transformation of the sand cores which are used to get specific cavities within the casting material. Grounded on their large inner surface, high gas absorption capacity and low thermal conductivity aerogels are able to minimize these defects (see fig. 1).[1,2] Resulting exhaust gases can be bound physically or chemically on their inner surface. Recently granulated aerogels as additives lead to benefits in aluminum and brass alloy castings. Within this work high temperature stable Si-O-C aerogels are synthesized and their effects on bronze casting are analyzed. These aerogels could be synthesized by pyrolysis of the appropriate organic-inorganic hybrid system. They need to withstand temperatures above 1200-1300 °C for a period of time and be stable under oxidizing conditions. The poster describes the synthesis of the Si-O-C aerogels, their thermal and mechanical properties as well as their ability of gas adsorption by measuring the inner surface.