成果報告書詳細
管理番号20120000000931
タイトル*平成23年度中間年報 水素製造・輸送・貯蔵システム等技術開発 水素ステーション機器要素技術に関する研究開発 水素用アルミニウム材料の評価・開発(1)
公開日2013/3/25
報告書年度2011 - 2011
委託先名国立大学法人茨城大学
プロジェクト番号P08003
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:委託先名:国立大学法人茨城大学
1.研究開発の内容及び成果等
以下に研究開発項目ごとに内容と成果を述べる。
a) 内圧型高圧水素環境下引張・疲労試験装置の製作
図1に高圧水素充填装置の概略(完成図)を示す。製作前は、図のV1とV2を一つのニードル弁(流量調節可能)とする予定であったが、ニードル弁の耐圧性能の関係で、設計の変更を余儀なくされた。
英文要約Title: Development of Technologies for Hydrogen Production, Delivery and Storage Systems. Research and Development of Elemental Technologies for Hydrogen Station Components. Assessment and Development of Aluminum Materials for Hydrogen (FY2010-FY2012) FY2011 Annual Report (1)
The results obtained were summarized in terms of each research item as follows:
a) Fabrication of tensile and fatigue testing apparatus using a test piece with high pressure inside
A cylindrical tensile test piece was filled with argon gas of about 7MPa in its hollow space, and then immersed in liquid nitrogen. After the valve was closed, the test piece was re-heated to room temperature. By this operation, the pressure inside the test piece was found to rise to twice of the original pressure. Actual hydrogen filling and tests will be carried out in fiscal year of 2012.
b) Tensile and fatigue tests under a humidity-controlled atmosphere
Fatigue-crack-propagation and fracture-toughness tests were conducted to investigate the effects of external hydrogen on the fatigue-crack-propagation property and fracture toughness in 6061-T6 and 7075-T6 plates. No change was found in fatigue-crack-propagation rate or fracture toughness when the atmosphere was changed from laboratory air to the air saturated with heavy-water vapor.
c) Thermal desorption spectroscopy (TDS) using deuterium to investigate the amount of invading hydrogen
During the above tests in the air saturated with heavy-water vapor, samples were cut from crack front and then subjected to TDS. It is concluded that no increase in the amount of deuterium was detected in this kind of samples by applying the tensile load. This was attributable to the impossibility of sample cutting from the region ideally close to the crack without containing the crack surface; crack surface was presumed to contain adsorbed hydrogen as well as hydrogen as hydrated oxide layer.
Similar TDS study was made by electrolytic hydrogen charging on the cracked and tensile-loaded specimens. Hydrogen amount was found to increase by the charging in the 6061-T6 specimen, while not in 7075-T6 specimen. This was presumed to be caused by the difference in the depth of hydrogen invasion during charging between the two alloys. Since the depth was reported to be 5μm in 7075-T6, sample for TDS was impossible to be cut from the invaded region. In contrast, it may have been successfully cut from the invaded region because the depth was reported to be 400μm in 6061-T6.
d) Investigation on the invasion site of hydrogen by means of tritium autoradiography (TARG)
The TARG carried out on 7075-T6 and 6061-T6 specimens with crack was not successful since the photographic emulsion layer was not able to be covered uniformly because of the presence of the crack. Then, tritium radioluminography in which an imaging plate is used instead of the emulsion was conducted on the same specimens. Although the resultant image was obtained successfully, tritium distribution was not obtained inside the specimens because of the lower sensitivity than TARG.
The TARG was also carried out on laboratory-fabricated Al-Zn-Mg alloys having MgZn2 phase particles with different volume fractions. The MgZn2 particles with a size larger than 0.5μm were found to be an invasion site for hydrogen. However, the amount of hydrogen and the depth of invasion were smaller than in Al-Cu-Fe alloys with approximately the same volume fraction of the second phase particles.
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