Hydrogen Reduction in MEP Niobium Studied by Secondary Ion Mass Spectrometry (SIMS)

Niobium, as pure metal and alloying element, is used in a variety of applications, among them in nuclear industries. Niobium is incorporated into nuclear fission reactors due to its enormous strength and low density. Surface finishing of niobium is often performed in electrochemical polishing proces...

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Bibliographic Details
Published in:Metals (Basel ) 2017-10, Vol.7 (10), p.442
Main Authors: Hryniewicz, Tadeusz, Konarski, Piotr, Rokicki, Ryszard
Format: Article
Language:English
Subjects:
Alloying elements
Chemical polishing
Corrosion resistance
de-hydrogenation
Electropolishing
Hafnium
Hydrofluoric acid
Hydrogen
hydrogen content
Hydrogen reduction
Hydrogen storage
Hydrogenation
magnetoelectropolishing (MEP)
Mass spectrometry
Methanesulfonic acid
Niobium
Nuclear fission
Nuclear reactors
Scientific imaging
Secondary ion mass spectrometry
SIMS
Smoothness
Spectroscopy
Surface finishing
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Summary:Niobium, as pure metal and alloying element, is used in a variety of applications, among them in nuclear industries. Niobium is incorporated into nuclear fission reactors due to its enormous strength and low density. Surface finishing of niobium is often performed in electrochemical polishing processes in view of improving its smoothness, corrosion resistance and its surface cleanability. However, the presently used electropolishing process (EP) is intrinsically linked to the subsurface hydrogenation of niobium, which measurably degrades its properties. This is why the annealing operation is used to remove hydrogen from electropolished niobium that is a costly and time-consuming process. The traditional electrolyte consisting of a mixture of 96% H2SO4/49% HF acids by volume in a 9:1 ratio has been substituted for the new one, being a mixture of 70% methanesulfonic acid with 49% hydrofluoric acid by volume in a 3:1 ratio. Moreover, the additional imposition of a magnetic field during the electropolishing process (MEP) further increases hydrogen removal, when compared to the hydrogen content achieved by the electropolishing process alone. The aim of the study is to reveal a methodic approach and showing decreasing hydrogenation of niobium samples after consecutive steps of electrochemical polishing. Secondary ion mass spectrometry (SIMS) was used to measure the hydrogen content in the surface layer of as-received AR niobium and in the samples after EP and MEP processes.
ISSN:2075-4701
2075-4701
DOI:10.3390/met7100442