Effect of Anisotropic Microstructure on the Viscous Properties of an LTCC Material

Abstract

The sintering behavior of a glass–ceramic (commercial material Ceramtape GC) was characterized using the discontinuous sinter‐forging technique. The uniaxial viscosity Ep and the viscous Poisson's ratio np of the composite body were determined as a function of density. Particular attention was paid to microstructural changes in order to quantify the anisotropy induced by load application. Pores and alumina particles were found to be both oriented perpendicular to the applied load direction. Finally, the experimental results were used to predict the value of the hydrostatic sintering stress.

Effect of uniaxial load on the sintering behaviour of 45S5 Bioglass® powder compacts

“…[11][12][13] The additional pressure increases the vacancy gradients naturally occurring during free sintering by solid state sintering, leading to increased driving force for material transport along grain boundaries, help to redistribute matter by viscous flow from regions of high local pressure to regions of low pressure or to improve particle rearrangement when a liquid phase is present. Glass based materials are very sensitive to mechanical stresses applied during sintering, as evidenced by Ollagnier et al 14 on Low Temperature Co-fired Ceramics and demonstrated in previous studies from dilatometric sintering data. 15 Stress induced anisotropy characterized by elongated pore shape and particular orientation could be observed in such materials.…”

Sintering of glass matrix composites with small rigid inclusions

“…16 Numerous papers focus on sintering of GMC concerning various applicative aspects, [17][18][19][20][21][22] the effect of rigid inclusions on the effective composite viscosity, 23 sinter anisotropy, 24 sinter retardation, [25][26][27] as well as the coexistence of solid and liquid phases. [28][29][30][31][32] Recently, sinter-forging or loading dilatometry studies on LTCC were focused on the anisotropic constrained sintering characteristics and microstructure of LTCC [33][34][35][36] analyzing respective viscous properties and sintering stress. The macroscopic description of constrained sintering was based on the concept of the viscoelastic analogy 37,38 and related constitutive models.…”

Microstructure evolution in thin zirconia films: Experimental observation and modelling

“…the integrated planar or segmented in series design of Rolls-Royce Fuel Cell Systems [4], the support does not shrink significantly during sintering of the electrolyte. The constraint generates a tensile stress during sintering that can lead to crack-like defects [5], delaminations and unfavourable pore orientation [6][7][8] in the films. If the defects and pores are large enough or penetrate the electrolyte film they can lead to lowered fuel efficiency and creation of local "hot-spots" that cause mechanical damage to the cells.…”