Pressure slip casting of coarse grain oxide ceramics

This contribution investigates the pressure slip casting of large coarse grain oxide ceramic bodies with a water soluble organic additive system. This organic additive system allows the preparation of a stable and pumpable slip containing alumina rich magnesia aluminate spinel of a size of up to 3 mm and an easy demolding of crack free, dimensionally stable bodies with negligible gradients due to sedimentation. Cut out samples of fired bodies are examined on apparent porosity, dynamic elastic modulus, modulus of rupture, and pore size distribution. Computer tomography showed very homogenous and dense bodies. The effects of different maximum grain sizes as well as possible sedimentation and segregation of the slip on the mechanical properties and microstructure are evaluated by using the Student's t-test. The most promising results of this study indicate that it is possible to reproducible fabricate coarse grain ceramics for refractory and other high temperature applications by pressure slip casting.