Stability of Materials in High Temperature Water Vapor: SOFC Applications

Opila, Elizabeth J.; Jacobson, Nathan

doi:10.1002/9780470943984.ch7

Cited by 3 publications

(5 citation statements)

References 28 publications

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“…Pure alumina samples that were hung using Pt‐30Rh wire were exposed inside the instruments to investigate the extent of Pt‐Rh evaporation from the wire, which was found to be negligible in steam at 1500°C. This is consistent with prior observations and in contrast to what is expected in O 2 environments …”

Section: Methodssupporting

confidence: 93%

“…This is consistent with prior observations and in contrast to what is expected in O 2 environments. 42 (2) High-Temperature Furnace The HTF consists of two adjacent MoSi 2 resistance heating modules that heat a vertical high-purity alumina tube. Steam at 300°C was fed into the bottom of the tube and was preheated to 1000°C-1300°C after it passed the first heating module.…”

Section: August 2014mentioning

confidence: 99%

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Silicon Carbide Oxidation in Steam up to 2 MPa

et al. 2014

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Growth and microstructure of a protective or nonprotective SiO2 scale and the subsequent volatilization of scale formed on high‐purity chemical vapor deposited (CVD) SiC and nuclear‐grade SiC/SiC composites have been studied during high‐temperature 100% steam exposure. The environmental parameters of interest were temperature from 1200°C to 1700°C, pressure of 0.1 to 2 MPa and flow velocities of 0.23 to 145 cm/s. Scale microstructure was characterized via electron microscopy and X‐ray diffractometry. The Arrhenius dependence of the parabolic oxidation and linear volatilization rate constants were determined. The linear volatilization rate exhibited a strong dependence on steam partial pressure with a weaker dependence on flow velocity. At high steam pressures, the oxide scale developed substantial porosity, which significantly accelerated material recession. The dominant oxide phase for the conditions studied was cristobalite. The oxidation behavior of SiC/SiC composite was strongly dependent on the state of the surface, specifically whether steam could find easy entry into the material via surface‐exposed interface layers. For the case where these as‐machined interfaces were surface coated with matrix CVD SiC, composite recession was found to be essentially that of high‐purity CVD SiC.

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Section: Methodssupporting

confidence: 93%

Section: August 2014mentioning

confidence: 99%

Silicon Carbide Oxidation in Steam up to 2 MPa

et al. 2014

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“…According to E.J. Opila (33), Mn rich volatile compounds can form and this would be coherent with the previously observed Mn enrichment of the GS at the outlet. Similar features are presented in a recently published paper on operated stack (16).…”

Section: Inlet Fuel Sidesupporting

confidence: 86%

“…The presence of manganese on the exposed border of the GS-outlet segment 1 and its absence on the corresponding surface at the inlet suggests that the exhaust fuel stream carried a Mn rich volatile compound which coated the surface of the glass. There is not much literature on this phenomenon which can be related to a reduced stability of Mn oxides in water vapor rich atmosphere (33,34) and further experiments shall be performed in order to evaluate the evaporation kinetics according to the H 2 /H 2 O ratio in the fuel stream.…”

Section: Elements Distribution Of Crmentioning

confidence: 99%

Ageing of Materials at Inlet and Outlet Fuel Manifolds in a SOFC Stack

Piccardo

Andrea²,

Bongiorno³

et al. 2015

ECS Trans.

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Analyses performed on a stack operated for more than 4000h at 750°C at high fuel utilization (80%) revealed significant differences in aging behaviour of stack components when comparing fuel inlet and fuel outlet areas. Two samples were cut from the fuel inlet and outlet manifolds of the operated SOFC stack. The glass-ceramic sealing material and the interconnect alloy were exposed to a dual atmosphere (external air and internal fuel stream). The fuel composition was dry H 2 /N 2 (60:40 vol. %) at the inlet and H 2 O/H 2 /N 2 (48:12:40 vol. %) at the outlet. The stack was operated in co-flow configuration, with a large excess of air. It was found that the interfaces between the seal and the alloy were significantly affected by the difference in fuel composition. The sealant exposed to the outgoing air was significantly polluted by chromium generated in the stack and transported by the air stream. These investigations therefore reveal that the long-term evolution of the sealing and of the metallic support depends on the local conditions in the stack, as well as on additional interactions with other degradation phenomena.

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“…Therefore, a capillary made of a material that does not react with high temperature water vapor (e.g. Platinum 119 ) is needed to test the volatility of oxides that can form silicon containing oxides and test oxides with reduced SiO2 activity at temperatures greater than 1200°C. In addition, the increase in the ID of the fused quartz capillary with exposure time results in a decrease of the steam-jet velocity and change in Red for flow within the capillary.…”

Section: Y2o3mentioning

confidence: 99%

Matrix Development for Water Vapor Resistant SiC-Based Ceramic Matrix Composites

Golden¹

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Stability of Materials in High Temperature Water Vapor: SOFC Applications

Cited by 3 publications

References 28 publications

Silicon Carbide Oxidation in Steam up to 2 MPa

Silicon Carbide Oxidation in Steam up to 2 MPa

Ageing of Materials at Inlet and Outlet Fuel Manifolds in a SOFC Stack

Matrix Development for Water Vapor Resistant SiC-Based Ceramic Matrix Composites

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