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Development of the protecting method for hydrogen(and its isotopes) permeation through metallic pipes by cathodic polarization

金属管道氢（及其同位素）渗透阴极极化防护方法的研制

基本信息

批准号：
16360373
负责人：
FUKATSU Norihiko
金额：
$ 9.47万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

The permeation of hydrogen through the pipe made of Fe-Cr-Al heat-resisting alloy (Cr22%, Al5%, Fe63% usually called "Kanthal Alloy") was measured by coulometric titration method. Even without any pretreatments, the measured permeability coefficient was found about one thousandth of that of usual heat-resisting Fe-Cr alloy. The measured value was nearly equal with that of alumina ceramics of the compatible thickness with the oxide layer formed on the metallic pipe, which suggests that the hydrogen permeation through the Fe-Cr-Al alloy pipe is controlled by the alumina layer formed on the surface of the pipe.The electromotive force established across the oxide film formed on the surface of the Fe-Cr-Al pipe and its polarization effect were studied in order to examine the possibility of cathodic protection of the hydrogen permeation. By emf measurement the hydrogen potential in the alloy substrate was confirmed to be maintained at high value due to the chemical polarization effect which … More had been already pointed out by us. The effect of cathodic polarization on the hydrogen permeation, however, was not confirmed clearly because the oxide film was made unstable by polarization in the reducing condition and also the permeation rate was naturally at very low value. Therefore, the pipe of polycrystalline alumina ceramics with porous platinum electrodes on inner and outer sides were employed in the place of the oxide film formed on the surface of the metallic pipe and the effect of polarization on this sample was studied in detail.It was confirmed that hydrogen was incorporated or released from the bulk of alumina on the change of the polarization conditions. This phenomenon was analyzed by calculating the hydrogen chemical potential profile in the polarized specimen. Based on this analysis, the solubility of hydrogen into the commercial polycrystalline alumina was determined. After a period of cathodic polarization by imposing 0.8V at 1573 K, it was observed that the permeation through the alumina pipe was perfectly blocked. Therefore, the possibility of cathodic protection of hydrogen permeation of a metallic pipe was confirmed if the stable alumina film doped with bivalent elements was formed on the surface of the pipe.The new phenomena such as the extraordinary incorporation of hydrogen at initial stage of oxidation of the metal, the super saturation of hydrogen into alumina, and the new mechanism relating with the hydrogen/proton electrode reaction were observed in the course of this study. The possible explanations of these phenomena were also given in the sub works of this research. Less

用库仑滴定法测定了Fe-Cr-Al耐热合金（Cr22%, Al5%, Fe63%，通常称为Kanthal合金）管中氢气的渗透率。在不进行任何预处理的情况下，测得的渗透系数约为一般耐热铁铬合金的千分之一。测量值与金属管材上形成氧化层的相容厚度的氧化铝陶瓷的测量值基本相等，说明Fe-Cr-Al合金管材的氢渗透受管材表面形成的氧化铝层控制。研究了Fe-Cr-Al管表面氧化膜上的电动势及其极化效应，探讨了氢离子渗透阴极保护的可能性。电动势测量证实，由于化学极化效应，合金基体中的氢电位保持在较高的值，这一点我们已经指出。然而，阴极极化对氢渗透的影响并没有得到明确的证实，因为在还原条件下极化使氧化膜不稳定，并且渗透速率自然处于很低的值。因此，采用内外两侧有多孔铂电极的多晶氧化铝陶瓷管代替金属管表面形成的氧化膜，并详细研究了极化对该样品的影响。结果表明，随着极化条件的改变，氢从氧化铝中析出或掺入。通过计算极化样品中的氢化学势分布来分析这一现象。在此基础上，测定了氢在商业多晶氧化铝中的溶解度。在1573 K下施加0.8V阴极极化一段时间后，观察到氧化铝管的渗透被完全阻断。因此，如果在金属管道表面形成掺杂二价元素的稳定氧化铝膜，则证实了金属管道对氢渗透进行阴极保护的可能性。在研究过程中，观察到金属氧化初期氢的超量掺入、氢在氧化铝中的超饱和以及氢/质子电极反应的新机制等新现象。对这些现象的可能解释也在本研究的子著作中给出。少