成果報告書詳細
管理番号20120000000277
タイトル*平成23年度中間年報 水素先端科学基礎研究事業 水素先端科学基礎研究 水素雰囲気下におけるゴム材料の研究
公開日2013/3/20
報告書年度2011 - 2011
委託先名NOK株式会社
プロジェクト番号P06026
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:
1. 研究開発の内容及び成果等
水素エネルギー社会実現のために,燃料電池の水素利用技術の向上だけではなく,水素を安心して使うための安全性や信頼性を確保することが要求される.水素機器のガスシール部品としては一般的にゴムOリングが使用されるが,特に高圧ガスシールに用いられるゴム材料には,水素ガスに限らず高圧ガスを減圧した際にゴム内部の破壊(ブリスタ)が発生し,ゴム材料を激しく損傷させ,シール性に影響を与えることがある.その破壊状態はゴム材料の種類や圧力差,減圧速度などの使用環境条件,Oリング寸法およびシール溝設計の影響を受けることが知られている.よって,高圧ガス環境下でゴムシールを使用する場合,ブリスタを発生させないことが技術的な課題である.前年度までにOリング材料および平面固定溝の設計について,高圧ガス環境下での基礎データを収集している.またブリスタの発生・成長を可視化することで現象を把握した.本年度からOリングの疲労耐久試験によるシール設計指針や寿命推定,実用配合ゴム材評価など,実用化を念頭に置いた検討も開始した.
英文要約Title: Fundamental Research Project on Advanced Hydrogen Science. Research on rubber composites under high-pressure hydrogen gas. (FY2010-2012) FY2011 Annual Report

A 70MPa high-pressure hydrogen tank applied for FCV (Fuel Cell Vehicle) system requires 5,500 times seal durability with pressurized and decompressed hydrogen gas cycles. When rubber composites were used at the high-pressure gas, internal cracks (blister) sometimes occurred, and the seal function degrades with the blister growth. Therefore it is necessary to develop a product with reliability and safe technology for the hydrogen energy society realization. In previous fiscal year, we have evaluated the gland design for hydrogen equipment with O-ring. We have also visualized O-ring behavior with gas decompression by using special viewable pressure vessel with a glass window and transparent rubber O-ring specimens in terms of some gases. In the latest year, we have started studies for practical use such as a static seal design of flat surface or cylindrical seal, long-term seal durability and material development for the high-pressure hydrogen seal.
The main content of execution in FY2011 is as follows:

(1) O-ring gland design guideline for a flat static seal
A rubber O-ring exposed to high-pressure gas generally swells by solution of gas molecules. If O-ring gland design such as a filling ratio and squeeze ratio which are recommended to general use were applied to the high-pressure seal, a fracture referred by swelling occurred in rubber seal.
The design of a flat static seal for hydrogen equipment was evaluated with ethylene-propylene rubber (EPDM) and silicone rubber (VMQ) O-ring specimen. The obtained design was applied to the small pressure vessel of O-ring durability test equipment in (3) investigation.

(2) O-ring gland design evaluation for a cylindrical static seal
A majority sealing method of high-pressure hydrogen equipment like as receptacle is a cylindrical static seal. In order to estimate the O-ring gland design for a cylindrical surface static seal, we developed compact high-pressure vessel possible to set at flexible filling ratio and squeeze ratio. It was confirmed that the O-ring gland design for a cylindrical static seal was evaluated by some fundamental research. In the next year, a cylinder static seal will be examined, and the assessment data based on various conditions will build up.

(3)Long-term durability test
Since high safety and maintenance free are required for hydrogen devices, a long-term seal durability test is important for industrial use of rubber seal for high-pressure hydrogen. A long-term seal durability test of rubber O-rings is conducted by an advanced durability tester improved safety, supply method of hydrogen and gas accumulator volume and evaluated 5,500 pressure cycle test. Some evaluations about extracted issues of the tester and fundamental research for sealing durability were investigated.

(4)Visualizing fracture behavior
We used transparent O-ring specimens molded by EPDM and VMQ to visualize blisters with an optical microscope. We also developed a high-pressure container enabling visualization of internal changes of the rubber O-ring caused by pressurization/decompression of high-pressure gas.
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