Modeling the Lamination of a Multilayered Tape Cast Ceramic Component With Fugitive Phases Before Sintering

A small finished ceramic component with micro-channels or other complex geometry requires a high degree of dimensional accuracy. The accuracy of the finished ceramic component depends upon the accuracy of the unfired ceramic body before sintering. One approach to creating micro-channels in ceramics is the fugitive phase approach. In this approach a sacrificial material is placed within the unfired ceramic to form channels or voids. The fugitive phase is removed or sacrificed during the subsequent sintering. For this paper, the authors examine the lamination step of the fugitive phase approach computationally. In the lamination step layers of unfired tape cast ceramic and layers of fugitive phase material are pressed together before sintering. The geometry examined in this paper is a quarter-symmetry model of a ten ceramic layer and nine fugitive phase layer structure. Three dimensional modeling is used to capture out of plane motion, displacement of the fugitive phase pieces, viscoelastic deformation, and rebounding when the layered structure is removed from the die press. The unfired ceramic is modeled as tape cast mullite and the fugitive phase is paper. The fugitive phase is modeled as linear elastic while the unfired ceramic is modeled as viscoelastic at a range of temperatures. The authors examine the filling of voids, pressure gradients, and conditions during unloading.