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A New Method Of Measuring Hydrogen Diffusivity By Hydrogen Permeation Technique I: Theoretical Modeling

Published online by Cambridge University Press:  10 February 2011

Tong-Yi Zhang  and
Yong-Ping Zheng
Tong-Yi Zhang
Affiliation:
Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
Yong-Ping Zheng
Affiliation:
Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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Abstract

A new model on hydrogen permeation is proposed, considering absorption and desorption processes on the sample surfaces. Analytical solution, satisfying the flux continuity rather than the concentration boundary conditions, is derived from the model. Drift velocity through surface and drift velocity in bulk are introduced and their ratio determines the validity of the time-lag model. When the ratio of drift velocity through surface over that in bulk approaches infinity, the proposed model is reduced to the time-lag one. The diffusivity and the drift velocity through surface can be evaluated by fitting the entire normalized permeation curve. The obtained results can predict the effects of temperature, sample thickness and energy barriers of absorption and desorption on the permeation process. The thickness effect occurred in using the time-lag model is well explained by the effects of absorption and desorption on the permeation process.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 513: Symposium H – Hydrogen in Semiconductors and Metals , 1998 , 137
Copyright
Copyright © Materials Research Society 1998

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References

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