Hydrogen Permeation through Layered Metallic Films

金属-氢体系的应用之一是制备透氢的金属薄膜。透氢膜不仅可用于氢气的提纯，还可作为氢气抽真空的窗口，避免真空因氢气泄漏而降解。本工作的目的是发明一种离子驱动下的层状金属膜吸氢窗口，当真空室内的氢气分压高于外部时，可渗透膜起到真空窗口的作用，反之则成为泄漏窗口。通过振荡渗透实验研究了氢在多层膜中的分布和扩散规律。氢在层状薄膜中的流动可以用各层中的溶解度和扩散系数以及界面上恒定流动的边界条件来合理地表示。考虑到平均注入范围两侧的扩散和表面反应，分析了离子驱动的渗透。结果表明：铜包铁膜从铜侧照射后，回流减小，渗透流量增加；选择合适的扩散层和阻挡层组合，离子驱动渗氢可以实现高效的氢气排出窗口。

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.