成果報告書詳細
管理番号20120000000676
タイトル*平成23年度中間年報 固体酸化物形燃料電池システム要素技術開発 基礎的・共通的課題のための研究開発 高温円筒横縞型耐久性の評価と不純物に対する影響評価
公開日2014/5/17
報告書年度2011 - 2011
委託先名三菱重工業株式会社
プロジェクト番号P08004
部署名新エネルギー部
和文要約
英文要約Abstract

In order to understand and clarify degradation phenomena and mechanism of segmented-in-series tubular type cell stack
used at high temperature, we analyzed correlations of performance degradation and microstructure change or material
inter-diffusion at three phase boundary region depending on change of power generation test condition in this project.
Since a metal tube for air supply / discharge was installed in the generator room at high temperature,
it was presumed that Cr poisoning was one of the causes of degradation.
For this reason, the metal tube was changed into a ceramic pipe and the durability test was carried out.
Furthermore, examinations for predicting durability of module, i.e., temperature distribution,
high utilizations of fuel and air, influence of air containing impurities, were also executed.
The influence of thermal insulation was investigated as impurities of air supplied to a cell stack in the module.
The cell stacks after the durability tests were analyzed with universities and research institutions and technical
issues were extracted to improve the durability.
Degradation rate of mean voltage applying the LSM-YSZ cathode interlayer decreased from 0.83 to 0.76%/1000 h
by the measure against Cr poisoning using the ceramic tube.
Then the amount of chromium deposition at the cathode/electrolyte interface vicinity decreased from hundreds of ppm to several ppm.
In order to suppress interdiffusion at interface vicinity of cathode/LSM-YSZ interlayer/electrolyte,
cathode interlayer changed into SDC, since the interdiffusion of composition element contained in the layers was observed.
The mean voltage of cell stack applying the SDC interlayer started the deterioration after about 2700 hours,
and degradation rate of 2700 to 6000 hours decreased to 0.13%/1000 h at the test of homogeneous temperature at 900℃.
A cell stack increasing the density of interconnect part overlapping electrolyte with SDC interlayer was fabricated
and the durability test was conducted at 900℃.
Then the deterioration of improved cell stack was not observed in the durability test of 5000 h.
Tendency which the degradation rate of cells at 800℃ or less increases was observed in the temperature distribution test.
Degradation rate of the durability test attaching thermal insulations around a cell stack increased equally,
but the high-utilizations of fuel and oxidant did not much influence the degradation.
As a result of analyzing the cell stacks with SDC interlayer after the durability tests,
dense layer was observed at the interface of LSCM/SDC and the density of SDC interlayer increased,
but no degradation was observed at 900℃. Further, pores were formed at the interface of LSCM/SDC and SDC layer.
Elemental distribution maps of cross sections showed that Sm and Mn diffused and the micro structure changed.
The tendency for the dense layer of an interface to become thick was observed with lowering the temperature.
This phenomenon was presumed that the diffusion velocity of Mn in LSCM has influenced.
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