Microstructural Characterization of Alumina Films During Constrained Sintering

Abstract

Alumina films were sintered on a rigid substrate to different densities. Stereological measurements suggest that microstructural anisotropy develops during the final stage of sintering, which can be interpreted in terms of the elimination of pore sections rather than anisotropic growth of isolated particle necks. Pore separation seems to be a better measure than grain intercept when compared with phenomenological models.

Constrained sintering kinetics of 3YSZ films

“…They suggested that this was because of the development of anisotropy in the microstructure of the constrained films and a resulting modification of the isotropic viscous model was developed to include anisotropy in the microstructure [15,16]. They found anisotropic shrinkage in sinter-forging experiments on alumina compacts consistent with the theory.…”

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

“…25 For real and more heterogeneous materials, this may not be the case. It was for example observed on alumina layers that the number of pores per area decreases for densities above 90%, 26 meaning that smaller pores disappear. Here, on the opposite, the number of pores per unit area increases significantly especially for the specimens sinter-forged at 1050 • C. Nevertheless, this result has to be correlated with the typical pore size, characterized by the average area of the pore sections.…”

Constrained sintering of 8 mol% Y2O3 stabilised zirconia films

“…Bordia and Guillon [20,21] modified the isotropic viscous model to anisotropic viscous behaviour and applied it successfully to sinter-forging of alumina compacts. However, the theory is difficult to apply to constrained films because it requires two independently measured (or modelled) free strain rates and two viscous Poisson's ratios corresponding to in-plane and out-of-plane principal directions.…”