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Absorption Mechanism of Hydrogen into Molten Aluminum

铝液吸氢机理

基本信息

批准号：
07455431
负责人：
FUKATSU Norihiko
金额：
$ 1.66万
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：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455431/
关键词：
aluminum hydrogen absorption permeation diffusion alumina proton solid electrolyte

项目摘要

It has been well known that the extremely larger amount of hydrogen is absorbed in molten aluminum kept in air than that expected from the hydrogen pressure in syrrounding atmosphere. The following investigations were performed to confirm that the proton conduction in oxide film formed on the melts is concerned essentially with the mechanism of the absorption. At first, the hydrogen permeation through the polycrystalline sintered alumina were measured by the apparatus which is newly developed using oxide proton conductor. The amount of permeation was found to be proportional to about the tenth power of the hydrogen pressure at the higher pressure side. This result suggests that the movable species in alumina is not diatomic molecule as in silica glass but charged species such as proton. The amount of permeation was observed to decrease when liquid aluminum was contact with the higher pressure side of the alumina specimen. This phenomena imply that the permeation through alumina results from the unbipolar diffusion of proton and aluminum ion to the opposite directions with each other. Next, the electromotive force generated across the oxide film formed on the surface of the molten aluminum was measured by the newly designed apparatus. The polarity of measured emf was coincide with that estimated from the assumption that the film worked as the solid electrolyte having protonic and aluminum ionic conduction. The value was in the range of the theoretical ones calculated assuming that the transport number of proton and that of aluminum ion was unity respectively.These observations support strongly the model proposed by us that the extraordinary hydrogen absorption of aluminum melted in air is originated from the chemical pumping mechanism due to extremely large difference of aluminum potentials across the thin oxide film formed on the surface of the melt.

众所周知，在空气中的铝液中所吸收的氢比周围大气中的氢压力所能吸收的氢要多得多。下面的研究证实了在熔体上形成的氧化膜中的质子传导本质上与吸收机制有关。首先，利用新研制的氧化物质子导体装置，测定了氢在烧结多晶氧化铝中的渗透率。研究发现，在高压侧，渗透量与氢压力的十分之一成正比。这一结果表明，氧化铝中的可移动物质不是硅玻璃中的双原子分子，而是质子等带电物质。当铝液与氧化铝试样的高压侧接触时，观察到渗透量减少。这一现象表明，通过氧化铝的渗透是由质子和铝离子向相反方向的非双极扩散引起的。其次，用新设计的仪器测量了铝液表面氧化膜上产生的电动势。所测电动势的极性与假设薄膜作为质子和铝离子导电的固体电解质所估计的极性一致。该数值在假设质子输运数和铝离子输运数为1的理论计算范围内。这些观测结果有力地支持了我们提出的模型，即在空气中熔化的铝的特殊吸氢是由于在熔体表面形成的薄氧化膜上铝电位的极大差异引起的化学泵送机制。