Structural transition of Ti-Cr-V alloys with hydrogenation and dehydrogenation and the improvement of their hydrogen storage properties by heat treatment

Ti-Cr-V 합금의 수소화-탈수소화에 따른 상천이 및 열처리에 의한 수소저장특성의 향상

  • You, Jeong-Hyun (Dept. of Materials Sci. & Eng., Chonnam National University) ;
  • Cho, Sung-Wook (Minerals & Materials Processing Research Division, Korea Institute of Geoscience & Mineral Resources) ;
  • Shim, Gun-Choo (Minerals & Materials Processing Research Division, Korea Institute of Geoscience & Mineral Resources) ;
  • Choi, Good-Sun (Minerals & Materials Processing Research Division, Korea Institute of Geoscience & Mineral Resources) ;
  • Park, Choong-Nyeon (Dept. of Materials Sci. & Eng., Chonnam National University) ;
  • Choi, Jeon (Dept. of Advanced materials Eng., Hanlyo University)
  • 유정현 (전남대학교 신소재공학부) ;
  • 조성욱 (한국지질자원연구원) ;
  • 심건주 (한국지질자원연구원) ;
  • 최국선 (한국지질자원연구원) ;
  • 박충년 (전남대학교 신소재공학부) ;
  • 최전 (한려대학교 신소재공학부)
  • Published : 2006.06.15

Abstract

The alloys which compositions were represented by the formula, $Ti_{(0.22+X)}Cr_{(0.28+1.5X)}V_{(0.5-2.5X)}$ ($0{\leq}X{\leq}0.12$), had the total hydrogen storage capacity higher than 3 wt% and the effective hydrogen storage capacity higher than 1.4 wt%. Particularly, among all the tested alloys, the $Ti_{0.32}Cr_{0.43}V_{0.25}$ alloy exhibited the best effective hydrogen storage capacity of 1.65 wt%. Furthermore, the reversible bcc${\leftrightarrow}$fcc structural transition was observed with hydrogenation and dehydrogenation, which predicted the possibility of pressure cycling. EDS analysis revealed micro-segregation, which suggested the necessity of microstructure homogenization by heat treatment. The $Ti_{0.32}Cr_{0.43}V_{0.25}$ alloy was selected for heat treatment and for other related studies. The results showed that the total and the effective hydrogen storage capacity increased to 3.7 wt% and 2.3 wt%, respectively. The flatness of the plateau region was also greatly improved and heat of hydride formation was determined to be approximately -36 kJ/mol $H_2$.

Keywords

Ti-Cr-V alloy;Hydrogen storage;Heat treatment;Heat of hydride formation;Structural transition

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