Hydrogen Permeation through Layered Metallic Films

点击翻译按钮获取中文摘要

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.