Aerogels as Nanoadditives for Foundry Sands

The techniques to produce cores with bonded sands are well established. Conventional binder systems, organic as well as inorganic ones, are widely used in sand casting foundry applications. There are still many open issues to reduce casting defects associated with the sand-binder system as discussed previously. It was also shown that RF aerogels as binders can overcome some of the problems encountered with conventional polymeric binders. 

In Table 34.1, some tested nanoadditives and their properties are listed. 

The aerogels or xerogels used are first pulverized with a cross hammer mill to fit the particle size distribution of the sand grains. A substitution of sand between 2 and 10 vol% by nanoadditives is suitable and sufficient. Sand and nanoadditives are mixed with a given type of binder and are then ready for molding. 

Chemical material Silica m-SUica Silica m-Silica Organic RF 

Currently, systematic studies are carried out to optimize the core and casting quality as a function of the used sand-binder system in combination with aerogelic nanoadditives. 

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