Shape Distortion and Delamination During Constrained Sintering of Ceramic Stripes: Discrete Element Simulations and Experiments

Abstract

Particle‐based simulations using the discrete element method are applied for the sintering of thin ceramic stripes that are constrained by a rigid substrate. The inhibition of lateral particle movement in vicinity of the substrate leads to a preferred shrinkage direction perpendicular to the substrate, which causes shape distortion as well as delamination of the stripe at the interface edges. Multiple processing parameters are varied in simulations to analyze their influence on the mentioned effects. The amount of particle rearrangement and the height to width aspect ratio of the cross‐section are identified to be factors that determine the level of shape distortion and edge delamination. The simulation results are compared with measurements of stripes produced by soft micromolding in capillaries. Good accordance is observed regarding parameters like axial and lateral shrinkage or delamination angle.

Finite Element Modeling of Camber Evolution During Sintering of Bilayer Structures

“…Continuum theory of sintering, in its current state, is not able to account for these losses of continuity. The continuum theory of sintering could be combined with damage models or meso‐scale models in order to describe the development of these micro‐cracks and the consequent reduction of stresses. It is beyond the scope of this work to pursue such enrichments of the continuum theory of sintering.…”

Three-dimensional shrinkage behavior of green tapes derived from spherical-shaped powders: Experimental studies and numerical simulations

“…35,36 Since the sintering simulations are used only for qualitative investigations the model parameters for the powders had not been determined in detail. Instead, existing data of an alumina powder have been used 36 and the systems were scaled to conform to the properties of the aforementioned study.…”

Crack formation in ceramic films used in solid oxide fuel cells

“…For example, Henrich et al [12] found that crack initiation in the constrained film is related to particle rearrangement: if rearrangement is suppressed, cracks tend to form more easily because of increased local stresses. Rasp et al [13] found that particle rearrangement also affects the delamination of ceramic strips: an easier particle rearrangement inhibiting delamination at the edges of the ceramic strips. The work of Martin et al [10,14] led to the conclusion that, although geometrical constraint is necessary for a defect to grow into a crack, the presence of an initial defect is not a necessary condition to initiate cracks.…”

“…However the continuum mechanic analysis has difficulty in explaining how crack initiates. In recent years, some progress has been made in the fundamental understanding of crack initiation by using discrete element modelling (DEM) [10][11][12][13]. For example, Henrich et al [12] found that crack initiation in the constrained film is related to particle rearrangement: if rearrangement is suppressed, cracks tend to form more easily because of increased local stresses.…”