Ceramic and metal-ceramic components with graded microstructure

At the Fraunhofer IKTS the principle of manufacturing of components with graded microstructure by multilayer technology is investigated. The main goal was the production of components with enhanced properties by the combination of different materials or porosities in one component. To demonstrate the possibilities of the multilayer technology carbon-free refractories, made of Ca-aluminate/Al2O3 or MgO-stabilized ZrO2 with graded porosity, were developed to achieve properties which are equivalent to the carbon-containing refractories. Other demonstrators combine stainless steel (17-4PH) and zirconia to address applications like filters or cutting tools. The manufacturing of multilayer composites by aqueous ceramic tape technology allows an environmental-friendly production of components with large dimensions and gradient structures regarding porosity and phase composition. Thereby, different amounts of pore forming agents added to the different used green tapes adjust the porosity. The resulting different properties in the gradient structure shall result in improved thermal shock properties of the materials. To combine different materials in one multilayer different green tapes were produced and laminated to one multilayer.Not only planar structures, but also cylindrical structures with a radial gradient of the microstructure and the resulting properties can be realized by applying a winding technology known from the paper technology.For the lamination of the multilayer, a special joining suspension was used. SEM-images of the sintered components show the perfect connection between the single layers within the produced structures