Hydrogen Permeation through Layered Metallic Films

金属-氢体系的应用之一是制备可透氢金属膜。该透氢膜既可用于氢气的净化，又可作为抽氢窗口，避免氢气泄漏对真空的破坏。本工作的目的是在离子驱动渗透下，利用层状金属薄膜来发明一种氢气排出窗。当真空室中氢气的分压高于外部时，可透膜起疏散窗的作用，反之则成为泄漏窗。薄膜必须有一定的渗透屏障，需要疏散时需要有一定的驱动机构来跨越屏障。采用振荡渗透实验研究了氢在多层膜中的分布和扩散。氢在层状膜中的流动可以用每一层的溶解度和弥漫性以及界面处恒定流动的边界条件来合理表达。考虑离子注入平均范围两侧的扩散和表面反应，对离子驱动渗透进行了分析。渗透流量随速率决定步骤的不同而用辐照通量的不同函数表示。结果表明：从Cu侧辐照Cu包覆Fe膜时，回流减少，渗透流量增加；选择扩散层和阻挡层的良好组合，可以通过离子驱动渗透来实现高效的氢排放窗口。

One of the Application of metal-hydrogen system is to fabricate a hydrogen permeable metalic film. The hydrogen permeable film can be used not only for purification of hydrogen but also for hydrogen evacuating window to avoid the degradation of vaccum by hydrogen leakage. The object of this work is to invent a hydrogen evacuating window by layered metallic films under ion driven permeation.When the partial pressure of hydrogen in a vaccum chamber is higher than outside, the permeable film works as a evacuating window, but in the opposite it becomes a leaking window. The film must have some barrier for permeation, and some driving mechanism is necessary to surmount the barrier when evacuation is needed.The distribution and diffusion of hydrogen in multi-layered films were studied by oscillating permeation experiments. The flow of hydrogen through the layered films could reasonably expressed using solubility and diffusibity in each layer and the boundary condition of constant flow at the interfaces.Ion driven permeation was analized taking into account the diffusion and surface reaction on both side of the mean range of the implantation. The permeation flow was expressed by a different function of irradiation flux depending on the rate determining step.The conclusion is as follows: when a Cu coated Fe film is irradiated from Cu side, back flow is diminished and permeation flow increases.Selecting a good combination of diffusion layer and barrier layer, an efficient hydrogen evacuation window can be operated by ion driven permeation.