Aqueous pressure slip casting of coarse-grained, carbon-containing refractories

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The aim of the project is to develop in the frame of basic research suitable shaping conditions for the application of pressure slip casting to coarse-grained, carbon-containing refractories. The influence of different grain size distributions based on the Dinger and Funk model approach on the rheological and casting behaviour, the microstructure, and the properties of refractory is investigated. One of the main challenges is the development of a suitable slurry composition providing sufficient wettability of the carbon and preventing sedimentation of the coarse grains. A novel, environment-friendly binding agent mixture is used. After optimising the rheological behaviour of the suspensions, the green body formation from these slurries in a pressure filtration device and the compressibility of the cake in a compression-permeability cell are examined. Then, casting in a commercial slip casting machine is investigated. A computer tomograph is used for detecting flaws in the ceramic, such as cavities and gradients in porosity. Furthermore, a so-called order parameter is determined by image analysis using methods of point process statistics and correlated with the material properties depending on the grain size distribution. The project should provide the basis for a new processing for coarse-grained, carbon-containing refractories with complex geometries by a near-net shape forming technology, with improved properties and no damage of the coarse grain.