Mechanical properties of aerogel composites for casting purposes

Abstract

Polymeric aerogels are used in this study to bind foundry sand forming thus a new kind of mould and core material called AeroSand. A core and mould material in general shall be able to withstand all handling stresses in a foundry shop, withstand the thermal and mechanical stresses exerted onto them during casting, but should also easy removable from a casting. Therefore mechanical properties are important besides others and this paper therefore concentrates on bending and compression strength of AeroSands. It is shown that the strength levels obtainable with aerogel binders are comparable to conventional binder systems. One essential advantage of AeroSands, namely the easy core removal, is not payed off by a loss in strength. The mechanical properties can be explained using a simple extension of the Griffith criterion taking into account the microstructure of the sand aerogel composite and the fracture path.