气态储氢性能
( 浙江大学 材料科学与工程学系, 杭州 310027)
摘 要: 纳米晶Mg2-xTixNi0.8Cr0.2 (x=0.05, 0.10, 0.15, 0.20) 四元合金由纯Mg, Ti, Ni, Cr粉在773K经4h烧结后机械球磨而成。 该合金具有良好的活化性能和吸氢动力学性能。合金在393K, 4.0MPa氢压条件下, 2min内便可以完成总吸氢量的75%(质量分数)以上, Mg1.95Ti0.05Ni0.8Cr0.2最大吸氢量可达到3.35%。 在493K, 0.1MPa条件下可快速放氢, Mg1.80Ti0.20Ni0.8Cr0.2在18min内便可完成放氢过程, 总放氢量为2.17%。 所有合金具有良好的低温吸氢性能, 353K时Mg1.85Ti0.15Ni0.8Cr0.2合金最大吸氢量可达到2.08%。 XRD分析结果显示, Ti替代Mg后, 合金中主要存在Mg2Ni与Ni两相, 另外, 还有微量的Mg与TiNi相, TiNi相弥散分布在合金中, 对合金的吸放氢性能有一定的催化作用。
关键字: 烧结; 球磨; 储氢; Mg2Ni合金; 纳米晶
tetragonal nanocrystalline
Mg2-xTixNi0.8Cr0.2 alloy
( Department of Materials Science and Engineering,
Zhejiang University, Hangzhou 310027, China)
Abstract: Nanocrystalline Mg2-xTixNi0.8Cr0.2(x=0.05, 0.10, 0.15, 0.20) alloys were prepared by solid-sintering at 773K for 4h and subsequent ball milling. The as-milled alloys show good activation properties and hydrogen absorption kinetics. The nanocrystalline alloys finish more than 75%(mass fraction) of full hydrogen storage capacity in 2min at 393K under hydrogen pressure of 4.0MPa, and the maximum absorbed hydrogen content of nanocrystalline Mg1.95Ti0.05Ni0.8Cr0.2 alloy reaches 3.35%. The nanocrystalline alloys desorb H2 at 493K and under pressure of 0.1MPa rapidly. Mg1.80Ti0.20Ni0.8Cr0.2 alloy desorbs 2.17% H2 in 18min at 493K. In addition, the absorption kinetic of the nanocrystalline alloys is good at low temperatures. The full hydrogen storage of nanocrystalline Mg1.85Ti0.15Ni0.8Cr0.2 alloy reaches 2.08% at 353K. XRD analysis shows that the partial substitution of Ti for Mg results in the formation of Mg2Ni-Ni complex phase and precipitation single Mg and TiNi phase after milling, which improve mainly the absorption/desorption kinetics properties.
Key words: sintering; ball milling; hydrogen storage; Mg2Ni alloy; nanocrystalline