日本金属学会誌

J. Japan Inst. Metals, Vol. 69, No. 9 (2005),
pp. 841-847

Hydrogen Permeation of Pure Niobium Metal in Highly Soluble Hydrogen State

Tomonori Nambu1, Nobue Shimizu1,, Hisakazu Ezaki1, Hiroshi Yukawa2 and Masahiko Morinaga2

1Department of Materials Science and Engineering, Suzuka National College of Technology, Suzuka 510-0294
2Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603

Abstract:

The hydrogen permeation through pure niobium metal was investigated using a gas permeation technique, focusing mainly on the measurements in a highly soluble hydrogen state. The hydrogen diffusion was found to be the rate-determining step for the hydrogen permeation reaction. However, the Sieverts law that the hydrogen solubility in a metal is proportional to the square root of hydrogen pressure, was no longer satisfied in the experimental condition of the temperatures of 473 K to 673 K and the applied pressures of 260 kPa at the inlet and 60 kPa at the outlet for hydrogen. This was mainly due to the presence of a large amount of soluble hydrogen in the metal under this condition. As a result, the measured apparent hydrogen permeability decreased monotonously with decreasing temperature in pure niobium. This was completely the reverse of the temperature dependence of the hydrogen permeability in the low solubility state where the Sieverts law was satisfied. It was stressed here that the permeation measurement of hydrogen in the high solubility state was indeed necessary for getting some performance data of metal membranes in practical use.


(Received 2005/6/23)

Keywords:

hydrogen permeability, niobium, hydrogen solubility, hydrogen diffusion


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