Theoretical and experimental study of optimal sintering condition for flat ceramic substrates with graded porous structure

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A numerical simulation is presented on the sintering of porous alumina structures prepared by a controlled sedimentation technique. By forming this functionally gradient material with a very broad powder size distribution, the samples were able to remain at through sintering. This experimental result is reflected in the present simulation results which incorporated particle size distribution effects.In general, sintering functionally gradient ceramics can often introduce defects. Despite these common problems, the asymmetric structures considered in this work featured a vertical functionality of continuously overlapping broad powder size distributions in the structure. This arrangement served to homogenize sintering rates. Modelling presented in connection with this shows that such structures can be readily sintered without warpage or cracking. To demonstrate these effects, a finite element method numerical simulation was developed to model the sintering characteristics of porous asymm … More etric ceramic structures by incorporating the powder particle size distribution into the model as a field variable.The key for being able to predict a non-warped structure was the incorporation into the model of the powder particle size distribution. Across the vertical section of the structure, the distributions were broad and overlapping, all with a significant fines tail. These characteristics accelerate and homogenize local sintering rates, such that the net result is a non-warped fused structure.This work presented novel advances in the sintering model such that the contributions to the desired product properties attributable to particle size distribution effects can be demonstrated. These additions to the model produced numerical results which properly match observed structural profiles of physical samples. Sample geometry, porosity and particle size distribution evolutions were traced alongside measurements made on physical specimens. In general the model corresponded well with the experimental observations. The correct accounting of observed trends lends confidence to the underlying sintering mechanisms incorporated into the model. Less