Highly Porous Ceramic Foams

One example of refractory materials developed at Fraunhofer-Center HTL is highly porous ceramic foams, which are produced using a specially developed direct foaming process. This manufacturing process begins with the production of a slurry consisting of water, ceramic powder and foaming agents, binders and stabilisers. This slip is mechanically whipped into a highly porous slip foam using simple equipment technology. The latter is then filled into a desired, near-net-shape mould, hardened and dried. After hardening and demoulding, the green parts show a high stability and can be mechanically processed if required. Subsequently, the organic components are burnt out and the moulded parts are sintered. By means of the direct foaming process, a wide range of ceramic powders (e.g. aluminium oxide, cordierite, mullite) can be processed close to the final contour into highly porous foamed mouldings using inexpensive organic starting materials that are harmless to health. The refractory components produced in this way offer potential for applications such as lightweight refractory bricks or insulating bricks.