Constrained sintering kinetics of 3YSZ films

Constrained sintering of Bi2O3‐doped ZnO

“…The above results are consistent with those observed in the polycrystalline Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 and TiO 2 +CuO, but different from those reported in the polycrystalline ceramic systems such as ZnO, Al 2 O 3, and ZrO 2. This explains why the polycrystalline ZnO + 1wt% Bi 2 O 3 , Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 and TiO 2 + CuO systems can be densified under constrained sintering at temperatures close to those required for free sintering.…”

“…Root causes including presence of in‐plane tensile stress, development of anisotropic microstructure and densification mechanism shift from a fast grain boundary diffusion to a slow lattice diffusion controlling kinetics have been proposed to explain the above densification retardation under constrained sintering of polycrystalline ceramic systems. The in‐plain tensile stress ( σ ), which is generated due to the elimination of linear shrinkage in the X‐Y directions during constrained sintering, is an apparent counter stress against sintering driving force.…”

“…The in‐plain tensile stress, which reduces the driving force of densification, yields poorer and slower densification compared with free sintering. Moreover, the in‐plane tensile stress changes the direction of diffusing atoms from grain boundary to lattice diffusion, resulting in an anisotropic microstructure during constrained sintering of polycrystalline ceramic systems . This slows down the densification further because the lattice diffusivity is much smaller than that of grain boundary diffusivity in polycrystalline ceramics.…”

Heterogeneous multilayer dielectric ceramics enabled by ultralow‐temperature self‐constrained sintering

“…However, addition of glass phase would inevitably sacrifice a great portion of electrical properties of the heterostructures, which limits the application of this method to certain microwave dielectrics. The second one is applying a uniaxial pressure to the rigid substrates attached to the top and bottom surfaces of the heterogeneous samples to inhibit the in‐plane shrinkage during sintering process . Unfortunately, applying external pressure and additional machining procedures including addition and removal of rigid substrates significantly increase the processing costs, rendering this approach disadvantageous for mass production.…”

Constrained Sintering in Fabrication of Solid Oxide Fuel Cells

“…In both cases, the individual constituent layers experience substantially different shrinkage rates, resulting in a variety of microstructural heterogeneities and the consequent performance degradation of solid oxide fuel cells at the level of both individual cells and stacks. Therefore, it is important to understand the effect of constrained sintering on microstructure evolution in both multiphase composite components themselves, as well as in cells, particularly from the viewpoint of flaw generation during fabrication and the subsequent structural damages and/or failure during operation [6,7,18,19,20,21,22,23,24]. In SOFC development, it has been acknowledged that constrained sintering generally leads to inadequate film density and unfavorable pore structures [25] and, to address this issue, research efforts have been devoted to understanding the microstructure evolution, stress development and defect formation based on experimental and theoretical approaches [26,27,28,29,30].…”