International Journal of Hydrogen Energy, Vol.44, No.23, 12277-12287, 2019
Preparation of Cr2O3/Al2O3 bipolar oxides as hydrogen permeation barriers by selective oxide removal on SS and atomic layer deposition
Iron-nickel based stainless steel (SS) applied in nuclear plants as a substrate material barely suppresses the permeation of hydrogen plasmas, which are mainly composed of positive and negative hydrogen ions with trace amounts of non-ionized hydrogen atoms. In this work, a new Cr2O3/Al2O3 bipolar oxide barrier was prepared using atomic layer deposition (ALD) of Al2O3 on a Cr2O3 layer that was generated by removing partial oxides with cyclic voltammetry (CV) of SS that had been pre-oxidized at 550 degrees C in air. We found that a small layer of alpha-Al2O3 was formed by the template effect of Cr2O3 at the interface of this composite film. The hydrogen permeation behavior of this bipolar oxide barrier in a fusion reactor was simulated with hydrogen-discharging plasma treatment. The results demonstrated that the hydrogen permeation resistance of this bipolar oxide was superior to the original oxide or a Cr2O3 film. Impressively, hydrogen plasma treatment repaired the bipolar oxide via reduction of the defective CrO3, resulting in an improvement in the hydrogen permeation resistance. These findings demonstrate a novel method of hydrogen permeation barrier preparation on SS, providing insight into hydrogen barrier construction for future nuclear energy applications. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.