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Dimensional control is one of the basic problems in ceramic processing, especially for tape cast ceramic sheets which are used to build up multilayer structures for high-integrated components. Uncontrolled anisotropic shrinkage can cause geometrical distortion and circuit failure of multilayer ceramics during sintering. The understanding of the relationship between green tape microstructure and shrinkage anisotropy is of great importance for further miniaturization of multilayer devices. In this study, alumina powders with spherical particle shape were used to cast green tapes. The microstructure as well as the pore orientation and the shrinkage behavior were analyzed. According to the sintering theory, grain growth and pore elimination are the two most important mechanisms to describe sintering shrinkage. In this work, three-dimensional shrinkage behavior of tape cast alumina powders with spherical particle shape was investigated and correlated with pore orientation in the microstructure. Specifically, the reason for the different shrinkage in z-direction compared to the lateral shrinkage is in focus. The study is based on experiments as well as on mathematical visualization.

A novel Monte Carlo model for the simulation of sintering processes is introduced. Different from previous models, local interface curvature is considered in the acceptance of diffusion steps. This enables the investigation of the effects of interface energies on the sintering process. Sintering paths are calculated for various microstructures and interface energies. Results are interpreted in the framework of thermodynamic criteria for homogeneous sintering processes which were presented recently.

Micro porous syntactic foams were successfully produced by pressure-assisted infiltration of sintered borosilicate glass bubble structures with AlSi9Cu3 and ZnAl4Cul alloy melts. Specimens with densities as low as 1 g/cm(exp 3) for aluminium and 3 g/cm(exp 3) for zinc and good infiltration qualities could be obtained whereas tests with the magensium alloy MgA15Zn led to extensive reactions between the glass and the magnesium melt. Compression tests with aluminium matrix specimens showed that this material has a very high compression strength and behaves almost like an ideal crash energy absorber. It could be shown that due to its strictly closed and microscopic-scale porosity this kind of foams can be surface treated e.g. by copper-plating and chromatizing or by anodizing processes.