Affiliation:
1. KTH, Royal Institute of Technology (KTH)
2. Szakálos Material Science AB
Abstract
For long time it is known that protons in aqueous solutions have a detrimental effect on
metallic materials. Relatively recently, it has also been observed in aqueous solution that the pitting
corrosion resistance of Cr, stainless steel 304 and 310 decreases and the anodic dissolution rate
increases due to the presence of hydrogen in the metal. In gas phase a high oxidation rate has been
observed for hydrogen containing Cr and Fe. Hydrogen in the substrate can also enhance the oxidation
of Fe in SS 316 and As in GaAs. All these results suggest enhanced dissolution in aqueous solution and
enhanced oxide growth at the oxide/gas interface in gas phase oxidation due to hydrogen promoted
outward-transport of substrate components. A possible mechanism for such out-transport is an
increased metal ion diffusivity in the metal-oxide due to a high abundance of metal ion vacancies
generated by hydrogen. In contrast to all the above examples, also positive effects of hydrogen have
been identified under certain conditions. In an attempt to understand both the negative and the positive
effects the concept of a beneficial, balanced oxide growth is used. In this concept a certain amount of
hydrogen can be beneficial in the oxidation by improving the balance between oxygen-ion and metalion
transport, leading to more dense and protective oxides. Depending on the temperature, H2 in air is
considered as either a sink or a source for hydrogen in materials.
Publisher
Trans Tech Publications, Ltd.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Cited by
7 articles.
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