Deposition of Conductive Oxide Coatings on Steel Interconnects of Solid Oxide Fuel Cell (original) (raw)
Related papers
Journal of the European Ceramic Society, 2006
The chemical interaction between Fe-Cr alloy interconnect and constituent oxides of Sr-doped LaMnO 3 (LSM) coating, La 2 O 3 , SrO and Mn 2 O 3 , is investigated at 800-900 • C in air. The Cr deposition reaction between the Fe-Cr alloy metallic interconnect and oxides varies significantly with the nature of the oxides. The interaction between the Fe-Cr alloy and La 2 O 3 and Mn 2 O 3 oxide coatings primarily results in the formation of LaCrO 3 and (Cr, Mn) 3 O 4 while in the case of SrO oxide coating, Cr 2 O 3 is the main product. In the case of LSM coating, the formation of (Cr, Mn) 3 O 4 and Cr 2 O 3 is identified. The results indicate that the chemical interaction between the Fe-Cr alloy interconnect and LSM coating is most likely related to the surface oxide species such as SrO and MnO x initially enriched or segregated on the surface of LSM particularly in the early stages of the reaction.
Journal of Materials Engineering and Performance, 2004
The requirements of low-cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. The performance of steel plates with multilayer coatings, consisting of CrN for electrical conductivity and CrAlN for oxidation resistance, was investigated. The coatings were deposited using large area filtered arc deposition technology, and subsequently annealed in air for up to 25 hours at 800 °C. The composition, structure, and morphology of the coated plates were characterized using Rutherford backscattering, nuclear reaction analysis, atomic force microscopy, and transmission electron microscopy techniques. By altering the architecture of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitude. Electrical resistance was measured at room temperature.
Journal of Power Sources
Manganese cobalt spinel oxides are promising materials for protective coatings for solid oxide fuel cell (SOFC) interconnects. To achieve high density such coatings are often sintered in a two-step procedure, involving heat treatment first in reducing and then in oxidizing atmospheres. Sintering the coating inside the SOFC stack during heating would reduce production costs, but may 2 result in a lower coating density. The importance of coating density is here assessed by characterization of the oxidation kinetics and Cr evaporation of Crofer 22 APU with MnCo 1.7 Fe 0.3 O 4 spinel coatings of different density. The coating density is shown to have minor influence on the longterm oxidation behavior in air at 800 °C, evaluated over 5000 h. Sintering the spinel coating in air at 900 °C, equivalent to an in-situ heat treatment, leads to an 88 % reduction of the Cr evaporation rate of Crofer 22 APU in air-3% H 2 O at 800 °C. The air sintered spinel coating is initially highly porous, however, densifies with time in interaction with the alloy. A two-step reduction and re-oxidation heat treatment results in a denser coating, which reduces Cr evaporation by 97 %.
Electrophoretic deposition of MnCr 2 O 4 coating for solid oxide fuel cell metallic interconnects
2014
In the present study, Mn-Cr spinel powder was synthesized through a solid state reaction. In the next step, the electrophoretic deposition (EPD) method was used to apply the MnCr 2 O 4 spinel, as an oxidation-resistant layer on SUS 430 stainless steel with a potential of 300 V/cm. The coated and uncoated samples were then pre-sintered in air at 900°C for 3h, followed by cyclic oxidation at 800°C for 500h. In order to study the effect of reducing pre-sintering atmosphere on oxidation resistance, the coated specimen was pre-sintered in 5% H 2 /Ar at 900°C for 3h, followed by cyclic oxidation at 800°C for 500h. The results of the oxidation resistance tests revealed that the MnCr 2 O 4 spinel coating improved the oxidation resistance of the uncoated sample; and also, the oxidation rate constant (K p ) for pre-sintered coating in 5% H 2 /Ar was nearly 14 times smaller than that of the one pre-sintered in air.
2014
In the present study, Mn-Cr spinel powder was synthesized through a solid state reaction. In the next step, the electrophoretic deposition (EPD) method was used to apply the MnCr 2 O 4 spinel, as an oxidation-resistant layer on SUS 430 stainless steel with a potential of 300 V/cm. The coated and uncoated samples were then pre-sintered in air at 900°C for 3h, followed by cyclic oxidation at 800°C for 500h. In order to study the effect of reducing pre-sintering atmosphere on oxidation resistance, the coated specimen was pre-sintered in 5% H 2 /Ar at 900°C for 3h, followed by cyclic oxidation at 800°C for 500h. The results of the oxidation resistance tests revealed that the MnCr 2 O 4 spinel coating improved the oxidation resistance of the uncoated sample; and also, the oxidation rate constant (K p) for pre-sintered coating in 5% H 2 /Ar was nearly 14 times smaller than that of the one pre-sintered in air.
International Journal of Hydrogen Energy, 2017
One of challenges in improving the performance and cost-effectiveness of SOFCs (solid oxide fuel cells) is the development of suitable interconnects materials. Chromia-forming alloys and especially ferritic stainless steels, like Crofer22APU, are considered to be among the most promising candidate materials as interconnects in SOFC stacks. However, the performance of chromia-forming materials can be limited by the low electronic conductivity of the oxide scale (high ASR-area specific resistance-value). Such degradation are unacceptable regarding the long-term operation (>40 000 h). A previous study [1] demonstrated that in air, the addition of a nanometric reactive element oxide (La 2 O 3) layer applied by metal organic chemical vapor deposition (MOCVD) drastically improved both corrosion rate and electrical properties of Crofer22APU and Haynes230 alloys for 100 h at 800 8C. In this present study coating performances were checked after 10 months (7500 h) and 20 months (15 000 h) at 800 8C in air. The corrosion products were carefully analyzed by SEM, EDX, and XRD. ASR measurements are realized after long time exposure. This study demonstrates that the Crofer22APU alloy has a good oxidation resistance after 15 000 h in air but this alloy has an ASR value equal to 0.370 V cm 2. The coatings composed of a thin reactive element oxide such as La 2 O 3 resulted in an important improvement in the high temperature oxidation resistance; the ASR values are equal to 0.154 V cm 2. Haynes230 alloy has a better oxidation resistance but the formation of an insulating Al 2 O 3 /SiO 2 layer could be detrimental.
Materials and Corrosion, 2011
One of challenges in improving the performance and cost-effectiveness of SOFCs (solid oxide fuel cells) is the development of suitable interconnects materials. Chromia-forming alloys and especially ferritic stainless steels, like Crofer22APU, are considered to be among the most promising candidate materials as interconnects in SOFC stacks. However, the performance of chromia-forming materials can be limited by the low electronic conductivity of the oxide scale (high ASR-area specific resistance-value). Such degradation are unacceptable regarding the long-term operation (>40 000 h). A previous study [1] demonstrated that in air, the addition of a nanometric reactive element oxide (La 2 O 3) layer applied by metal organic chemical vapor deposition (MOCVD) drastically improved both corrosion rate and electrical properties of Crofer22APU and Haynes230 alloys for 100 h at 800 8C. In this present study coating performances were checked after 10 months (7500 h) and 20 months (15 000 h) at 800 8C in air. The corrosion products were carefully analyzed by SEM, EDX, and XRD. ASR measurements are realized after long time exposure. This study demonstrates that the Crofer22APU alloy has a good oxidation resistance after 15 000 h in air but this alloy has an ASR value equal to 0.370 V cm 2. The coatings composed of a thin reactive element oxide such as La 2 O 3 resulted in an important improvement in the high temperature oxidation resistance; the ASR values are equal to 0.154 V cm 2. Haynes230 alloy has a better oxidation resistance but the formation of an insulating Al 2 O 3 /SiO 2 layer could be detrimental.
Procedia Materials Science, 2015
In the present study, Cu-doped nano-La 0.8 Sr 0.2 MnO 3 (LSM) protective coating has been applied on SUS430 stainless steel alloy substrate by using a wet spray coating process combined with nitrate solution impregnation. The Cu-doped nano-LSM coating acts as a barrier to evaporation and migration of Cr-containing species from interconnect which is effective for preventing chromium volatilization from interconnect alloys in solid oxide fuel cells. Long-term isothermal and non-isothermal oxidation experiments for area specific resistance (ASR) measurements were investigated. The Cu-doped nano-LSM coating was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX) analyzer. The results of ASR test showed that doping of Cu as a transition metal dopant into LSM improves electrical conductivity.
Metallic materials in solid oxide fuel cells
Materials Research, 2004
Fe-Cr alloys with variations in chromium content and additions of different elements were studied for potential application in intermediate temperature Solid Oxide Fuel Cell (SOFC). Recently, a new type of FeCrMn(Ti/La) based ferritic steels has been developed to be used as construction material for SOFC interconnects. In the present paper, the long term oxidation resistance of this class of steels in both air and simulated anode gas will be discussed and compared with the behaviour of a number of commercial available ferritic steels. Besides, in-situ studies were carried out to characterize the high temperature conductivity of the oxide scales formed under these conditions. Main emphasis will be put on the growth and adherence of the oxide scales formed during exposure, their contact resistance at service temperature as well as their interaction with various perovskite type contact materials. Additionally, parameters and protection methods in respect to the volatilization of chromia based oxide scales will be illustrated.