| How does Ni doping into vanadium effect the vanadium compounds'deuterium activity, pressure boost and anti-poisoning functions were studied. In our work, materials preparation, physical chemistry properties and the relationship between composion, crystal structure and storage properties of V-Ni alloys were also carried out.The Inductively Coupled Plasma (ICP) results indicated that V-Ni alloys prepared by induction melting twice in the argon atmosphere could satisfy the demand of composition. The structures examined by X-Ray Diffraction (XRD) showing all the ingots were BCC phase when Ni content was not higher than 8.3%(atom fraction, similarly hereafter).Pure vanadium is difficult to be activated, which could be activated through 2 or 3 deuterium absorption-desorption cycles. The activation performances of modified vanadium were significantly improved by the addition of Ni. V100-xNix alloys were not easy to fully activated at deuterium pressure of 0.5 MPa. However, the alloys could be easily activated at first cycle when deuterium pressure was higher than 1.0MPa.At same deuterium pressure, V100-xNix alloys absorbed deuterium more quickly than pure V. When the initial deuterium pressure was not higher than 2.0MPa, the velocities of deuterium absorption increased with the increasing of Ni content. However, when initial deuterium pressure was up to 4.0 MPa, the velocities of deuterium absorption were decrease with increasing of Ni content.As V100-xNix alloys fully activated, the deuterium absorption velocities and ability of V100-xNix alloys fell down gradually with the initial temperature rise up when the temperature was not higher than 323K. When the temperature exceeded 323K, the velocities of deuterium absorption drop down rapidly. And when the temperature exceeded 423K, deuterium absorption was not obvious.When Ni content was not higher than 2.0%, the saturation capacity of deuterium absorption of V100-xNix alloys was as much as pure V. As Ni content exceeding 4.1%, the saturated deuterium absorption capacity of V100-xNix alloys drop fast, only for 50% of the theoretical value. Which indicated the saturated deuterium absorption capacity was effected seriously by content of Ni.After 8 cycles, pure V particle size became smaller clearly, turning into powder. V100-xNix alloys particle size diminished and tended to be well-distributed. The result showed that doping Ni into pure V could improve the performance of anti-pulverization.Samples after activation degassing were analyzed by XRD, the result showed that the structure of V91.7Ni8.3 was instable, with phase changing after times of cycles and high temperature activation. This resulted in new phase NiV3 taken place.Lattice constants of samples after activation degassing decreased and the variation increased with Ni content increased gradually. While Ni content was 8.3%, alloy lattice constants are not obvious, the change may be due to the NiV3 phase formation reduced the stress around crystal lattice.After poisoned by CO2, the faculty of pure V to recover deuterium absorption activation was poor; the deuterium absorption performances of V100-xNix alloys could be resumed to fully activation quickly.In summary, the deuterium absorption activity was obviously improved and the ability of anti-pulverization and anti-poisoning were enhanced by means of modification of V by doping metal Ni.therefore, V100-xNix solid solution is an excellent kind of hydrogen storage material with high equilibrium pressure, by varying Ni content, it maybe show different performances to satisfied our demand. It could be forecast that the kinds of materials showing an important application in hydrogen isotopes storage and compression. |
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