Predicting oxide stability in high-temperature water vapor

Opila, Elizabeth J.; Jacobson, Nathan; Myers, Dwight L.; Copland, Evan

doi:10.1007/s11837-006-0063-3

Cited by 188 publications

(129 citation statements)

References 51 publications

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“…In contrast, the content of CrO 2 (OH) 2 released by the MIC is governed by mass transport limitations, as suggested by Opila et al [47]. Except for the deposition process (see Ref.…”

Section: Transport Of Chromium Volatile Speciesmentioning

confidence: 92%

“…The situation is further complicated in a coated MIC. The use of thermodynamic data for the equilibrium partial pressure of CrO 2 (OH) 2 over Cr 2 O 3 therefore yields conservative lifetime predictions, even though the scatter in the thermodynamic data induces imprecision in the range of one order of magnitude [22,47,51]. Resistance against mass transport of CrO 2 (OH) 2 from the air channel to the active sites where it is electrochemically deposited, is neglected.…”

Section: Transport Of Chromium Volatile Speciesmentioning

confidence: 99%

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Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Nakajo

Mueller

Brouwer

et al. 2012

Journal of Power Sources

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h i g h l i g h t s< Analysis of the combined effect of multiple degradation processes in SOFC stacks. < Acceleration of the degradation and sequential activation of processes is predicted. < Optimisation of the operating conditions can extend lifetime by a factor up to 10. < Operating conditions for the highest performance and the best durability differ. < Overpotential rather than current density influences the degradation behaviour. a r t i c l e i n f o t r a c tThe degradation of solid oxide fuel cells (SOFC) depends on stack and system design and operation. A methodology to evaluate synergistically these aspects to achieve the lowest production cost of electricity has not yet been developed.A repeating unit model, with as degradation processes the decrease in ionic conductivity of the electrolyte, metallic interconnect corrosion, anode nickel particles coarsening and cathode chromium contamination, is used to investigate the impact of the operating conditions on the lifetime of an SOFC system. It predicts acceleration of the degradation due to the sequential activation of multiple processes. The requirements for the highest system efficiency at start and at long-term differ. Among the selected degradation processes, those on the cathode side here dominate. Simulations suggest that operation at lower system specific power and higher stack temperature can extend the lifetime by a factor up to 10, because the beneficial decrease in cathode overpotential prevails over the higher release of volatile chromium species, faster metallic interconnect corrosion and higher thermodynamic risks of zirconate formation, for maximum SRU temperature below 1150 K. The counter-flow configuration, combined with the beneficial effect of internal reforming on lowering the parasitic air blower consumption, similarly yields longer lifetime than co-flow.

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“…In contrast, the content of CrO 2 (OH) 2 released by the MIC is governed by mass transport limitations, as suggested by Opila et al [47]. Except for the deposition process (see Ref.…”

Section: Transport Of Chromium Volatile Speciesmentioning

confidence: 92%

Section: Transport Of Chromium Volatile Speciesmentioning

confidence: 99%

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Nakajo

Mueller

Brouwer

et al. 2012

Journal of Power Sources

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“…For the case of SiC and SiC composites, this entails the formation of the volatile Si(OH) 4 species [1,2]. A number of test techniques have evolved to study the phenomenon, including standard furnace thermogravimetric (TGA) and steam-jet [3,4].…”

Section: Introductionmentioning

confidence: 99%

Environmental resistance of a Ti2AlC-type MAX phase in a high pressure burner rig

Smialek

2017

Journal of the European Ceramic Society

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“…For other substrates without Mo such as cermets, SiC composites and ZrB 2 -SiC ceramics, the coating is applied with a two-step method: (1) chemical vapor deposition (CVD) of Mo by the decomposition of Mo(CO) 6 at 225°C; and (2) pack cementation, a CVD process, of Si and B (35 wt.% Si:1 wt.% B ratio) under Ar at 1000°C. Depositing Mo through the decomposition of Mo(CO) 6 results in complete surface coverage of the substrate, but the final Mo layer is less than 10 lm thick. This limits the total thickness of the oxidation-resistant coating and thus the Si and B reservoir size and, ultimately, the level of protection.…”

Section: Coating and Substrate Preparationmentioning

confidence: 99%

Environmentally Resistant Mo-Si-B-Based Coatings

2017

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High-temperature applications have demonstrated aluminide-coated nickel-base superalloys to be remarkably effective, but are reaching their service limit. Alternate materials such as refractory (e.g., W, Mo) silicide alloys and SiC composites are being considered to extend high temperature capability, but the silica surfaces on these materials require coatings for enhanced environmental resistance. This can be accomplished with a Mo-Si-Bbased coating that is deposited by a spray deposition of Mo followed by a chemical vapor deposition of Si and B by pack cementation to develop an aluminoborosilica surface. Oxidation of the as-deposited (Si ? B)-pack coatings proceeds with partial consumption of the initial MoSi 2 forming amorphous silica. This Si depletion leads to formation of a B-saturated Mo 5 Si 3 (T 1 ) phase. Reactions between the Mo and the B rich phases develop an underlying Mo 5 SiB 2 (T 2 ) layer. The T 1 phase saturated with B has robust oxidation resistance, and the Si depletion is prevented by the underlying diffusion barrier (T 2 ). Further, due to the natural phase transformation characteristics of the Mo-Si-B system, cracks or scratches to the outer silica and T 1 layers can be repaired from the Si and B reservoirs of T 2 ? MoB layer to yield a self-healing characteristic. Mo-Si-B-based coatings demonstrate robust performance up to at least 1700°C not only to the rigors of elevated temperature oxidation, but also to CMAS attack, hot corrosion attack, water vapor and thermal cycling.

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Predicting oxide stability in high-temperature water vapor

Cited by 188 publications

References 51 publications

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Environmental resistance of a Ti2AlC-type MAX phase in a high pressure burner rig

Environmentally Resistant Mo-Si-B-Based Coatings

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