固体氧化物燃料电池新型连接体材料的研究进展

连接体是固体氧化物燃料电池(SOFC)中的关键组件，对连接体的高性能需求一直制约着SOFC的商业化发展。随着SOFC的运行温度降低到800℃以下，廉价的高温抗氧化金属连接体材料取代掺杂铬酸镧(LaCrO₃)陶瓷的可能性大大增加。此外，为了优化连接体的性能，大量的导电/保护性涂层及新的复合材料也不断地涌现。综述了迄今为止连接体材料的发展现状，在对各种连接体材料以及涂层材料的性能和优缺点进行比较的同时，重点介绍了新开发连接体材料的研究进展，并对连接体材料的发展趋势进行了展望。     

SOFC合金连接体材料的研究进展

对固体氧化物燃料电池(SOFC)用合金连接体材料的研究进展进行了介绍,分别对镍基、铬基和铁基合金合金连接体材料的研究发展情况给予评述,对每种连接体材料的特点和存在的问题进行了详细的论述,并指明了各种合金连接体材料的今后发展趋势.最后着重指出铁基合金及其表面改性是今后连接体材料发展的主要方向.     

中温SOFC金属连接体材料的氧化规律和导电行为

系统地研究了SUS 430铁素体不锈钢在中温SOFC阴极气氛(空气)中的氧化动力学、表面氧化物特征以及表面氧化对导电行为的作用.通过750℃静态空气中的氧化实验得出氧化增重与氧化时间的动力学关系;采用"4点法"测量合金表面氧化膜的面比电阻(ASR);利用XRD和SEM表征表面氧化物的相结构、微观形貌及成分.实验发现,氧化动力学符合抛物线规律,并呈现出多级氧化现象;所生成的表面氧化物主要为Cr2O3和MnCr2O4;表面氧化物的ASR与测量温度之间的关系满足Arrhenius方程,并且在600～700℃之间,其斜率发生改变.结合氧化过程中的阳离子扩散、氧化物形成热力学以及半导体的导电机理对多级氧化动力学机制、氧化物相形成规律以及面比导电行为进行了理论分析.在此基础上,对SUS 430作为中温SOFC金属连接体材料的可能性做出了合理的评估.     

中低温固体氧化物燃料电池合金连接体保护涂层研究进展

Fe-Cr铁素体合金是中低温固体氧化物燃料电池理想的连接体材料,但其在高温下缺乏良好的抗氧化性能,且会引起阴极"Cr中毒"现象,影响了电池的高效安全运行,目前解决上述问题的主要方法是对合金连接体进行表面改性,在连接体表面开发导电性保护涂层。介绍了中低温固体氧化物燃料电池Fe-Cr合金连接体表面涂层材料的主要作用和具体要求,着重阐述了目前连接体涂层材料的主要类型及其研究进展,并指出了目前该领域研究中存在的问题及今后的发展方向。     

SOFC关键材料电化学表征方法

固体氧化物燃料电池(SOFC)是全固态的化学发电装置,其构成材料固体氧化物对SOFC性能的影响尤为重要。本文从材料对SOFC电化学性能影响的视角出发,立足电化学、固体电化学的基本原理,概述了SOFC构成材料的电化学表征方法,并将一些研究积累赘述文中,希望有利于材料的进一步研究。     

LaCrO3基陶瓷材料在SOFC中的研究进展

综述了LaCrO3材料在固体氧化物燃料电池(SOFC)中作为陶瓷连接材料、合金连接体的涂层材料以及新型阳极材料的国内外最新研究进展.介绍了LaCrO3作为陶瓷连接材料的使用要求,在热膨胀性能、烧结性能、电性能和化学稳定性能等方面的研究情况,并介绍了磁控溅射、等离子喷涂、溶胶-凝胶(Sol-gel)工艺等几种LaCrO3涂层材料制备方法以及LaCrO3作为新型阳极材料的催化性能、导电性能和热膨胀性能等方面的研究进展,对其发展前景进行了展望.     

玻璃和云母复合封接SOFC电池堆性能

封接技术是影响平板式固体氧化物燃料电池(SOFC)发展的关键技术之一。实验中用云母和Bi2O3-BaO-SiO2-RxOy(R=K,Zn,Al2O3,etc.)玻璃复合,将电解质(氧化钇稳定氧化锆,YSZ)支撑的电池和金属连接体(SUS430不锈钢)封接在一起,对封接后电池堆的封接性能和开路电压以及各组元热膨胀性能进行测试。结果表明:云母在室温到720℃的平均热膨胀系数为8.5×10-6 K-1,Bi2O3-BaO-SiO2-RxOy玻璃20℃到520℃的平均热膨胀系数为11.0×10-6/K,与YSZ和金属连接体匹配。云母的层状结构可以缓解因热膨胀系数不同而产生的应力,在高温状态下云母还能起到固定软化玻璃的作用。通过气密性和电性能测试,在电池堆工作状态下气密性良好,在操作温度为800～900℃下运行28小时,电池堆的开路电压(OCV)维持在1.0V以上,复合封料及其两边材料中的元素没有明显扩散。因此,云母和玻璃Bi2O3-BaO-SiO2-RxOy复合封接技术可适用于高温SOFC的封接。     

固体氧化物燃料电池(SOFC)制备方法的研究进展

固体氧化物燃料电池(SOFC)是解决未来能源问题的一种重要的方法.而制备方法是SOFC研究的一个重要的方向.介绍了SOFC电极材料以及制备方法在国内外的研究进展,介绍了固体氧化物燃料电池(SOFC)的阳极、电解质、阴极的制备及几种合成方法以及所取得的成果.     

低温固体氧化物燃料电池的复合电解质材料

固体氧化物燃料电池(SOFC)是一种高效、环保的发电装置。低温化是SOFC的主要发展方向。探索适合在低温(400~600℃)条件下操作的高性能电解质材料是SOFC低温化发展的关键。近年来,研究人员发展了新型的复合电解质材料,取得了较好的成果。本文综述了近年来低温SOFC复合电解质材料的研究进展,简要介绍了复合电解质材料的特点、类型和传导机理。     

低温固体氧化物燃料电池电解质材料

低温化是固体氧化物燃料电池(SOFC)发电技术的重要发展趋势。SOFC工作温度的降低不仅可极大地降低材料及制备成本,更重要的是可极大地提高其长期运行的稳定性。电解质是SOFC的核心部件,可以采用电解质薄膜化或新型电解质材料来降低SOFC的工作温度。本文概述了目前被广泛研究的低温SOFC的电解质材料,并从其结构及性能出发,重点阐述了它们各自的优点和局限性。     

Brazing of metallic conductors onto ceramic plates in solid oxide fuel cells Part II Attaching conducting wires

Commercialization of the solid oxide fuel cell (SOFC) will be facilitated by use of conventional materials and fabrication processes. In this paper, we discuss the results of brazing metallic wires, made of conventional heat-resisting alloys, onto metallic CrFe5Y₂O₃1 conductor plates in SOFC. Such wires would be used for the current transport between individual SOFC stacks and to the power-consuming device. Aluminum-alloyed ferritic stainless steels (iron, 20 to 25 wt% chromium, 4.5 to 6 wt% aluminum) and Inconel 617 were found to be suitable materials for the wires. They can be brazed onto CrFe5Y₂O₃1 using L-Ni 5 as filler for Inconel 617 and the ferritic steels, and Cr50Ni or L-Ni 5 for the ferritic steels. The effectiveness of the brazed conductor/CrFe5Y₂O₃1 joints was verified by monitoring their resistance at 1000°C in air for 1000 h.     

Opportunity of metallic interconnects for solid oxide fuel cells: a status on contact resistance

The status and opportunity of metallic interconnects for an anode-supported solid oxide fuel cell stack is reviewed with special emphasis on the variation of contact resistance of currently developed interconnects at operating temperatures, as well as the prevailing approaches to reduce contact resistance. It appears that without a coating, current metallic interconnects are not suitable for practical applications at 800 °C since they may cause drastic performance degradation of the stack within its expected service lifetime. Some guidelines in designing new metallic interconnects with both excellent oxidation resistance and reasonably low contact resistance in SOFC environments are set forth.     

平板型SOFC合金连接板的研究进展

从材料设计和表面处理方面综述了合金材料作为连接板的研究近况。合金连接板具有高的电子传导和热传导性,成本低,加工性能优良,合金材料表面氧化膜生长速率适中。经过表面处理的合金,在工作过程中涂层与基体发生反应生成更抗氧化的保护层,面电阻率进一步降低,具有很好的应用前景。     

Fabrication and characteristics of porous AISI 304L stainless steels by ceramic powder additions

Abstract

Porous AISI 304L stainless steels were fabricated by a new powder metallurgy technique, based on the addition of oxide based ceramic powders. The mixture of AISI 304L stainless steel powders and oxide based ceramic powders was compacted using a hand press at a pressure of 294 or 490 MPa. The green compacts were sintered at 1150 or 1200°C for 3 h in Ar gas atmosphere. The addition of oxide based ceramic powders into AISI 304L stainless steel powders gave rise to porous AISI 304L stainless steels with fine pores. Also, the addition of the ceramic powders increased the hardness.     

Characterization of Al rich oxide layers on austenitic stainless steels by fluorescence spectroscopy

Abstract

An Al rich oxide passivation technique has been developed to improve the corrosion resistance of the stainless steel to ozone added ultra-pure water. Fluorescence spectroscopy was applied to the study on the selective oxidation of aluminum containing austenitic stainless steel in low oxygen atmosphere at 1,353K. It was found that in the thermal oxidation under low oxygen pressure, the minor alloying constitution of Al resulted in the formation of thin oxide layers. The frequency shifts of fluorescence spectra show that the compressive stresses exist in the oxide layers as a result of the difference of the thermal expansion coefficients between substrate steels and α-Al₂O₃, and depends on the thickness of the oxide layers. It is confirmed that pure α-Al₂O₃ protective layers grown on the stainless steels, which remain stable and attached to the stainless steels in ozone added ultra-pure water. These act as a diffusion barrier and protect the stainless steels from the metal dissolution.     

Analysis of oxide layers on stainless steel (304, and 316) by conversion electron Mössbauer spectrometry

Stainless steels of type SUS304 and SUS316 were chemically treated and heated at various temperatures, and the oxide films formed on the surface were analysed by Auger electron spectrometry and conversion electron Mössbauer spectrometry. The outermost oxide layers of stainless steels were enriched with iron and chromium after heat treatment below 600° C and above 700° C, respectively. It was found that at least two magnetic components of iron species were present in the oxide layers of stainless steel heated below 600° C and that the fine particles of iron oxide are produced in the inner oxide layers of the samples prepared by heating at temperatures higher than 700° C. Only paramagnetic iron species were detected in the oxide layers of the stainless steel prepared by chemical treatment. The structures of the oxide layers produced by those heat and chemical treatments are proposed.     

固体氧化物燃料电池连接材料的研究进展

平板型燃料电池是固体电解质燃料电池的主要构成方式,而连接材料的研究是平板型燃料电池实用化研究的关键技术之一。本文简要介绍了连接材料的特点和主要存在的问题及今后的研究重点。     

新型复合支撑体共烧制备致密La0.7Ca0.3Cr0.97O3-δ连接体薄膜

为了解决固体氧化物燃料电池(SOFC)陶瓷连接材料的低成本制备难题,设计了与LaCrO3基连接材料和Ni基阳极均具有良好烧结匹配性能的新型复合材料NiO/La0.7Ca0.3Cr0.97O3δ(LCC97)作为管式SOFC的支撑体.详细研究了NiO含量(5wt%、25wt%、50wt%、75wt%)对复合支撑体的烧结性能、微观组织、孔隙率、电导性能、热膨胀系数等的影响,结果表明:LCC97与NiO具有优良的烧结和化学匹配性能,NiO/LCC97(1:1,wt%)具有最优的综合性能.以其为支撑体,采用浆料浸渍法制备LCC97湿膜,1400℃空气条件下共烧,获得了致密LCC97连接材料薄膜.     

Dense spinel MnCo2O4 film coating by aerosol deposition on ferritic steel alloy for protection of chromic evaporation and low-conductivity scale formation

Conducting ceramic layers with a spinel structure of MnCo₂O₄ and a thickness of ~3 μm were deposited on ferritic stainless steel (SS) by aerosol deposition (AD), for use as an oxidation-resistant coating layer on the metallic interconnects of a solid oxide fuel cell (SOFC). The microstructural changes in the interface between the MnCo₂O₄ and SS were analyzed, as were the subsequent electrical conductivity changes at an SOFC operating temperature of 800 °C in air. The coated spinel layers were dense without pores or cracks, and maintained good adhesion even after oxidation at 800 °C for 1,000 h in air atmosphere. Close observation of the interface between the coated spinel oxide and SS substrate indicated the presence of ~1-μm thick, Cr-rich scale formation; however no MnCrCoO₄ or MnCr₂O₄ spinel phase was detected. The area specific resistance (ASR) of the MnCo₂O₄-coated alloy after heat treatment at 800 °C for 1,000 h was 13.4 mΩ cm².