Structural characteristics and mechanism of hydrogen-induced disproportionation of the ZrCo alloy

Abstract

The intermetallic compound ZrCo was prepared, and its hydrogen-induced disproportionation in hydrogen desorption processes was investigated. The hydrogenation-dehydrogenation thermodynamics of the ZrCo alloy was evaluated by pressure-composition isotherm measurements at different temperatures. The kinetic processes of hydrogen-induced disproportionation at different temperatures under certain pressures were detailedly studied. The disproportionation rate of the ZrCo alloy increased with the increases of temperature and initial hydrogen pressure under experimental conditions. However, the maximum attainable extent of disproportionation did not change much with an increase in temperature or initial hydrogen pressure. The crystallographic structure analysis of the ZrCo alloy combining with its corresponding dehydrogenation kinetic curves under the conditions of an initial hydrogen pressure of 0.2 MPa and a temperature of 723 K indicated that the basic process of disproportionation reactions was composed of four stages: rapid dehydrogenation of ZrCoH₃, equilibrium of dehydrogenation, simultaneity of dehydrogenation and disproportionation, and completion of disproportionation.

Keywords

zirconium compounds / cobalt compounds / hydrogenation / dehydrogenation / structural analysis / thermodynamics

References

[1] Shmayda W.T., Mayer P. Uranium beds for temporary tritium storage. J. Less Common Met., 1984, 104(2): 239

[2] Mitsuishi N., Fukada S. Absorption and desorption of hydrogen with particle beds of several zirconium alloys. J. Nucl. Mater., 1990, 175(3): 209

[3] Devillers M., Sirch M., Bredendiek-Kämper S., Penzhron R.D. Characterization of the ZrCo-hydrogen system in view of its use for tritium storage. Chem. Mater., 1990, 2(3): 255

[4] Konishi S., Nagasaki T., Okuno K. Reversible disproportionation of ZrCo under high temperature and hydrogen pressure. J. Nucl. Mater., 1995, 223(3): 294

[5] Hara M., Okabe T., Mori K., Watanabe K. Kinetics and mechanism of hydrogen-induced disproportionation of ZrCo. Fusion Eng. Des., 2000, 49–50, 831

[6] Bekris N., Besserer U., Sirch M., Penzhorn R.D. On the thermal stability of the zirconium/cobalt-hydrogen system. Fusion Eng. Des., 2000, 49–50, 781

[7] Naik Y., Rao G.A. R., Venugopal V. Zirconium-cobalt intermetallic compound for storage and recovery of hydrogen isotopes. Intermetallics, 2001, 9(4): 309

[8] Hara M., Kanesaka I., Watanabe K., Kabutomori T. Durability of ZrCo and ZrNi against absorption-desorption cycles in hydrogen. Ann. Rep. Hydrog. Isot. Res. Center Toyama Univ., 1994, 14, 85.

[9] B.A. Hunter and C.J. Howard, LHPM: a computer program for Rietveld analysis of X-ray and neutron powder diffraction patterns, ANSTO Report, Sydney, 1998.

[10] Penzhorn R.D., Devillers M., Sirch M. Evaluation of ZrCo and other getters for tritium handling and storage. J. Nucl. Mater., 1990, 170(3): 217

[11] Irodova A.V., Somenkov V.A., Shil’shtein S.H., Padurets L.N., Chertkov A.A. Structure of ZrCoD₃. Kristallografiya, 1978, 23(5): 1044.