Improvement of sealing performance for Al2O3 fiber-reinforced compressive seals for intermediate temperature solid oxide fuel cell

Li, Ruizhu; Liang, Xiaopeng; Wang, Xiaochun; Zeng, Wenli; Yang, Jiajun; Yan, Dong; Pu, Jian; Chi, Bo; Li, Jian

doi:10.1016/j.ceramint.2019.07.209

Cited by 22 publications

(12 citation statements)

References 35 publications

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“…When the leakage occurred at the seals, the flow meter displayed the gas mass flow. Once the gas flow reached equilibrium, the leakage rates were recorded by mass flow (Alicat KM9901 America, Alicat Scientific, Tucson, AZ, USA) with a precision of 0.0001 sccm [ 26 ]. The leakage rates under thermal cycles and long-term operation were measured.…”

Section: Methodsmentioning

confidence: 99%

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Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell

et al. 2023

Molecules

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A reversible solid oxide cell (RSOC) integrating solid oxide fuel (SOFC) and a solid oxide electrolysis cell (SOEC) usually utilizes compressive seals. In this work, the vermiculite seals of various thickness and compressive load during thermal cycles and long-term operation were investigated. The leakage rates of seals were gradually increased with increasing thickness and input gas pressure. The thinner seals had good sealing performance. The compressive load was carried out at thinner seals, the possible holes were squeezed, and finally the leakage rates were lower. With a fixed input gas pressure of 1 psi, 2 psi, and 3 psi, the leakage rates of 0.50 mm vermiculite remained at around 0.009 sccm/cm, 0.017 sccm/cm and 0.028 sccm/cm during twenty thermal cycles, while the leakage rates remained at around 0.011 sccm/cm for about 240 h. Simultaneously, elemental diffusions between seals and components were limited, implying good compatibility. Furthermore, the open circuit voltage (OCV) remained at around 1.04 V during 17 thermal cycles, which is close to Nernst potentials. The stack performance confirmed that the vermiculite seals can meet the structural support and sealing requirements. Therefore, the vermiculite shows good promise for application in stacks during thermal cycles and long-term operation.

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Section: Methodsmentioning

confidence: 99%

“…Compressive seals are deformable under an external load and have been developed to overcome disadvantages of glass seals [ 26 , 27 , 28 ]. Compressive seals were developed to overcome the disadvantages of glass and glass–ceramic materials.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell

et al. 2023

Molecules

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“…For evaluation of the gas tightness of two brazed joints, the pressure drop method was adopted to measure the in-situ pressure changes inside the brazed samples [ 29 , 30 , 31 ]. Crofer alloy and YSZ with dimensions of 14 × 14 and 20 × 20 mm 2 were utilized as the substrates.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Vacuum Brazing of Metallized YSZ and Crofer Alloy Using 72Ag-28Cu Filler Foil

et al. 2022

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The study focused on dissimilar brazing of metallized YSZ (Yttria-Stabilized Zirconia) and Crofer alloy using BAg-8 (72Ag-28Cu, wt%) filler foil. The YSZ substrate was metallized by sequentially sputtering Ti (0.5/1 μm), Cu (1/3 μm), and Ag (1.5/5 μm) layers, and the Crofer substrate was coated with Ag layers with a thickness of 1.5 and 5 μm, respectively. The BAg-8 filler demonstrated excellent wettability on both metallized YSZ and Crofer substrates. The brazed joint primarily consisted of Ag-Cu eutectic. The metallized Ti layer dissolved into the braze melt, and the Ti preferentially reacted with YSZ and Fe from the Crofer substrate. The globular Fe2Ti intermetallic compound was observed on the YSZ side of the joint. The interfacial reaction of Ti was increased when the thickness of the metallized Ti layer was increased from 0.5 to 1 μm. Both brazed joints were crack free, and no pressure drop was detected after testing at room temperature for 24 h. In the YSZ/Ti(0.5μ)/Cu(1μ)/Ag(1.5μ)/BAg-8(50μ)/Ag(1.5μ)/Crofer joint tested at 600 °C, the pressure of helium decreased from 2.01 to 1.91 psig. In contrast, the helium pressure of the YSZ/Ti(1μ)/Cu(3μ)/Ag(5μ)/BAg-8(50μ)/Ag(5μ)/Crofer joint slightly decreased from 2.02 to 1.98 psig during the cooling cycle of the test. The greater interfacial reaction between the metallized YSZ and BAg-8 filler due to the thicker metallized Ti layer on the YSZ substrate was responsible for the improved gas-tight performance of the joint.

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“…Glass‐to‐metal compressive seals are an excellent option for the reliable fabrication of hermetic connectors, transducers, and electrical feed‐through seals, which benefit from their high mechanical strength and exceptional hermeticity 1–4 . In terms of these compressive seals, the compressive stress at the sealing interface, which is generated from the coefficient of thermal expansion (CTE) mismatch among different materials, is the key to achieving and ensuring long‐term hermeticity 5,6 . Hermeticity is related to stress distribution, cracks, and interfacial defects 6,7 .…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] In terms of these compressive seals, the compressive stress at the sealing interface, which is generated from the coefficient of thermal expansion (CTE) mismatch among different materials, is the key to achieving and ensuring long-term hermeticity. 5,6 Hermeticity is related to stress distribution, cracks, and interfacial defects. 6,7 If the glass region near the sealing interface undergoes weak compression, then failure may occur by interfacial debonding or by crack initiation within the glass, especially under demanding service conditions with high temperature and high pressure.…”

Section: Introductionmentioning

confidence: 99%

Calibration for determination of compressive stress in glass‐to‐metal seals via photoluminescence spectroscopy

Liu,

Cai,

Gong

et al. 2023

J Am Ceram Soc.

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Compressive stress in glass‐to‐metal seals is crucial to ensure sealing quality and service reliability. Photoluminescence spectroscopy (PS), which relies on the piezospectroscopic effect of Cr‐doped α‐Al2O3, shows promise for stress detection owing to its rapid detection, non‐destruction, and high resolution. The premise of the PS technique is to fill a glass matrix with alumina particles and detect signals from the alumina. In this study, the interaction between alumina particles and the glass matrix was analyzed to calibrate the measured stresses and investigate the stress state in the glass. Test results for glass‐to‐metal seals are believed to consist of simultaneous internal residual stress and external applied stress. The internal residual stress is formed due to the coefficient of thermal expansion mismatch between glass and alumina and is assumed to transfer by radial compression. In the experiment, it was detected by the PS technique and verified by X‐ray diffraction using an unstressed sample without metal housing. The external applied stress is formed due to metal housing compaction and possibly transferred by the shear effect. The stress distribution within the pre‐stressed sample containing metal housing was also measured by the PS technique. Then, calibrations were conducted on the measured stresses based on the deduced stress transfer relationships. Finally, finite element models were established to simulate the internal residual stress and external applied stress respectively to prove the validity of the calibration method, and mutually anastomotic results were obtained within the target margin of error.

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Improvement of sealing performance for Al2O3 fiber-reinforced compressive seals for intermediate temperature solid oxide fuel cell

Cited by 22 publications

References 35 publications

Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell

Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell

Vacuum Brazing of Metallized YSZ and Crofer Alloy Using 72Ag-28Cu Filler Foil

Calibration for determination of compressive stress in glass‐to‐metal seals via photoluminescence spectroscopy

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