Evaluation of hydrogen absorption behaviour during acid etching for surface modification of commercial pure Ti, Ti-6Al-4V and Ni-Ti superelastic alloys

Akira Nagaoka, Ken'ichi Yokoyama, Jun'ichi Sakai

    Research output: Contribution to journalArticle

    26 Citations (Scopus)

    Abstract

    The hydrogen absorption behaviour during acid etching for the surface modification of commercial pure Ti, Ti-6Al-4V and Ni-Ti superelastic alloys has been investigated on the basis of the surface morphology, electrochemical behaviour and hydrogen thermal desorption analysis. To simulate the conventional acid etching for the improvement of the biocompatibility of Ti alloys, the specimens are immersed in 1 M HCl, 1 M H2SO4 or 0.5 M HCl + 0.5 M H2SO4 aqueous solution at 60 °C. Upon immersion, commercial pure Ti absorbs substantial amounts of hydrogen irrespective of the type of solution. In H2SO4 or HCl + H2SO4 solutions, the hydrogen absorption occurs for a short time (10 min). For Ti-6Al-4V alloy, no hydrogen absorption is observed in HCl solution, whereas hydrogen absorption occurs in other solutions. For Ni-Ti superelastic alloy, the amount of absorbed hydrogen is large, resulting in the pronounced degradation of the mechanical properties of the alloy even for an immersion time of 10 min, irrespective of the type of solution. The hydrogen absorption behaviour is not necessarily consistent with the morphologies of the surface subjected to corrosion and the shift of the corrosion potential. The hydrogen thermal desorption behaviour of commercial pure Ti and Ni-Ti superelastic alloy are sensitively changed by acid etching conditions. The present results suggest that the evaluation of hydrogen absorption is needed for each condition of acid etching, and that the conventional acid etching often leads to hydrogen embrittlement.

    Original languageEnglish
    Pages (from-to)1130-1138
    Number of pages9
    JournalCorrosion Science
    Volume52
    Issue number4
    DOIs
    Publication statusPublished - 2010 Apr

    Keywords

    • A. Biomaterials
    • A. Nitinol
    • A. Titanium
    • C. Corrosion
    • C. Hydrogen embrittlement
    • C. Surface modification

    ASJC Scopus subject areas

    • Materials Science(all)
    • Chemical Engineering(all)
    • Chemistry(all)

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