Hydride dissociation and hydrogen evolution behavior of electrochemically charged pure titanium

Akito Takasaki, Yoshio Furuya, Kozo Ojima, Youji Taneda

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Abstract

A commercially pure α-titanium was electrochemically charged with hydrogen in a 5% H2SO4 solution at a current density of 5 kA m-2 for 14.4 ks (4 h), and the dissociation process of the electrochemically formed hydride and the evolution behavior of hydrogen from the samples were investigated by means of high temperature X-ray diffractometry, thermal desorption spectroscopy (TDS) and differential thermal analysis (DTA). The electrochemical charging produced δ-titanium hydride; this dissociated completely at temperatures around 600 K; (α + β) titanium then appeared, indicating that the hydride formed eutectoidally. The DTA detected the dissociation of the hydride (or (α + δ)-(α + β) boundary in the titanium-hydrogen system) as an endothermic peak. The TDS analysis, however, revealed that the accelerated hydrogen evolution could not be found at the dissociation temperature of the hydride but could be at higher temperatures. It was suggested that the hydride dissociation, (α + δ), into (α + β) two-phase region was not accompanied by hydrogen evolution from the samples, but the free hydrogen owing to the hydride dissociation was diffused into the samples. The peak temperatures of both DTA and TDS analyses shifted to lower temperatures with decreasing heating rate. The Kissinger plots fitted these results fairly well and indicated that the apparent activation energies for δ-hydride dissociation and hydrogen evolution were estimated to be about 106 kJ mol-1 and about 49 kJ mol-1 respectively.

Original languageEnglish
Pages (from-to)269-273
Number of pages5
JournalJournal of Alloys and Compounds
Volume224
Issue number2
DOIs
Publication statusPublished - 1995 Jul 1
Externally publishedYes

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Keywords

  • Electrochemical charging
  • Thermal analyses
  • Titanium
  • X-ray diffraction
  • δ-hydride

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Materials Chemistry
  • Metals and Alloys

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