Constrained sintering of Y2O3-stabilized ZrO2 electrolyte on anode substrate

Fabrication and characterization of Ni-SSZ gradient anodes/SSZ electrolyte for anode-supported SOFCs by tape casting and co-sintering technique

“…1 (a) it was evident that water evaporated from the starch at temperature around 100 C. In the temperature range of 250e300 C, there was a significant weight loss accompanied by a strong exothermic process. The starch decomposed into CO 2 , NO 2 and H 2 O at this temperature in air [25]. In the temperature range of 300e550 C, the rate of weight loss slowed down, the second exothermic peak corresponded to a second ignition of gaseous products from the residual carbon skeleton.…”

“…Large mismatches in shrinkage behavior result in the residual stress between the electrolyte layer and the anode layers at faster heating rate, leading to cracks and delaminations in the half cell. The low heating rate could suppress the cracks formation, and avoid exfoliation of the electrolyte layer from the anode layers [25]. The shrinkage mainly happened in the two sintering stages: 30e600 C and 800e1400 C. Additionally, the decomposition of organic additives also happened at about 30e600 C. Therefore, the two sintering stages applied a lower heating rate than the others, and the heating rate were 0.5 C/min (30e600 C), 3 C/min (600e800 C) and 1 C/min (800e1400 C) in our research.…”

“…Arc 1 and arc 2 of the electrochemical impedances are used to describe the cathodic and anodic electrochemical polarization losses, respectively. Arc 3 and arc 4 are used to describe gas diffusion and conversion in the cathode and anode, respectively [25]. The equivalent circuit was LR s (R 1 Q 1 ) (R 2 Q 2 ) (R 3 Q 3 ) (R 4 Q 4 ), where L was an inductance in series with R s as an ohmic resistance [15].…”

Constrained Sintering in Fabrication of Solid Oxide Fuel Cells

“…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]. For instance, the effects of particle size, size distribution, and sintering temperature on the sintering kinetics and microstructural evolution of a composite electrode were studied based on a three-dimensional Monte Carlo model [30], and the sintering model predicted that constrained sintering leads to an anisotropic microstructure, which becomes more isotropic with further densification [28].…”

“…For instance, the effects of particle size, size distribution, and sintering temperature on the sintering kinetics and microstructural evolution of a composite electrode were studied based on a three-dimensional Monte Carlo model [30], and the sintering model predicted that constrained sintering leads to an anisotropic microstructure, which becomes more isotropic with further densification [28]. The relationship between stress and the sintering profile has been studied using a continuum model [27], and the stress analysis revealed that the excessive residual stress that develops in constrained sintering is relieved by microcrack formation during subsequent cooling [29]. In the present study, the principles of constrained sintering for fabrication of a porous cathode and a dense electrolyte are presented to further improve our fundamental understanding and provide scientific basis for realizing the ideal architecture of solid oxide fuel cells.…”