Development of ceramic tapes for thermal shock resistant calcium aluminate refractory materials with graded porosity

At the Fraunhofer Institute for Ceramic Technologies and Systems the principle of manufacturing of carbon-free refractory components by multilayer technology is investigated. Two different material systems are under investigation: Ca-aluminate/Al2O3 and MgO-stabilized ZrO2. The manufacturing of multilayer composites by aqueous ceramic tape technology allows the production of components with large dimensions and gradient structures regarding porosity and phase composition, which yield to improved thermal shock properties of the materials. This paper presents the results of different characterization techniques for laminated and sintered multilayer as well as the orientation of pore formers inside the green tapes. The microstructure of the sintered multilayer and the interfaces be tween the tapes is characterized by scanning electron microscopy (SEM) on cross-sections. Tensile tests show the mechanical strength of the different laminates. Computer tomography allows looking for possible delaminations between the different tapes after the lamination, which can cause big defects in the sintered multilayer.