New lightweight kiln furniture - Production processes and properties

The main requirement on kiln furniture is the save support or transport of ceramic products during the thermal processing. Therefore, high compressive strength and high bending strength especially at high temperatures are needed. Thick dense or thick porous ceramic plates are state of the art. However, these structures have a high thermal mass, which has to be heated and quenched during each heat treatment cycle. Furthermore, a homogeneous temperature distribution in the kiln can only be realize at low heating or cooling rates. Due to these challenges, the manufacturing of a novel generation of kiln furniture with advanced properties (low density and heat capacity, high stiffness, good thermal shock behavior) has been investigated. This new approach was realized by the combination of different green ceramic pre-products made by tape casting or extrusion. Planar green tapes were laminated with a supporting structure including macroscopic cavities to allow passage of air or gas and additionally reduce the density of the structure. Due to the reduced heat capacity, the saving of energy and time up to 40% is possible, verified in different tests.