AB3和AB5合金混合物熱處理前後儲氫性能研究;Study on Hydrogen Storage of AB3 and AB5 Alloy Mixture Before and After Heat Treatment

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题名:	AB3和AB5合金混合物熱處理前後儲氫性能研究;Study on Hydrogen Storage of AB3 and AB5 Alloy Mixture Before and After Heat Treatment
作者:	阮氏金蓮;LIEN, NGUYEN THI KIM
贡献者:	化學工程與材料工程學系
关键词:	氫氣儲存;AB3 合金;Hydrogen storage;AB3 alloy
日期:	2025-01-22
上传时间:	2025-04-09 16:03:54 (UTC+8)
出版者:	國立中央大學
摘要:	為應對全球氣候的劇烈變化和溫室效應的影響，氫能源被認為是一種可行的解決方案，因為它被認為是一種清潔且可再生的能源。然而，氫分子的極低密度導致了運輸和儲存問題。因此，開發具有高儲氫能力的材料變得至關重要。 AB5合金是常見的儲氫材料，具有合理的儲氫能力。然而，AB5合金中包含大量的稀土金屬（Rare Earth Metals, REMs），其成本越來越高。因此，AB3合金由於使用較少的稀土金屬而更多地採用低成本金屬如Ca和Mg，在儲氫方面可能更具成本效益。與AB5合金相比，AB3合金不僅具有更大的儲氫容量，還具有較低的工作溫度和壓力。因此，AB3合金在某些應用中可以至少部分取代AB5合金。本研究的結果顯示了混合AB3和AB5對儲氫能力的影響。主要目標是研究AB3合金La0.7Ca0.7Mg1.6Ni9 在熱處裡前後的儲氫性能及其與熱處裡前後AB5的協同效應。首先，透過高頻感應加熱法製備了不同元素比例的La-Ca-Mg-Ni氫化合物。使用感應耦合等離子體（ICP）確定了合金的成分為La0.49Ca1.07Mg1.94Ni9和La0.56Ce0.38Ni5。為了研究熱處理對La-Ca-Mg-Ni/AB5氫化合物的影響，將一種AB3型La–Ca–Mg–Ni基儲氫合金在800℃的氬氣氣氛中熱處理48小時。透過電子探針顯微分析（EPMA）檢查了熱處理後樣品的局部化學成分。隨後使用X射線衍射（XRD）和透射電子顯微鏡（TEM）檢查了材料在熱處理前後的晶體結構和相變。 X射線繞射分析揭示了合金中存在兩種相，即FCC (La,Mg)Ni3相和HCP (LaNi5)相。最後，透過Sivert型設備研究了樣品的儲氫性能，並確定了樣品的壓力-組成-等溫線（PCI）曲線。結果表明，透過熱處理製備的AB3顯示出一個平坦的壓力平台，這表明合金具有很高的均勻性。純AB5和熱處理後AB5的儲氫容量在25℃、5 MPa氫充壓下分別為1.4 wt.% 和1.26 wt.%。相較之下，商業AB5型La0.6Ce0.4Ni5儲氫合金的PCI曲線顯示出較高的平台壓力和更大的滯後現象。在相同的氫充壓條件下，50 wt.% AB3和50 wt.% AB5合金的混合樣品的儲氫容量增加，顯示兩種合金混合的有益效果。綜上所述，本研究成功製備了AB3型La-Ca-Mg-Ni合金。透過XRD和TEM驗證了其FCC和HCP相結構。 EPMA分析顯示，經過熱處理後，AB3合金中僅鎂發生聚集，而其他元素則均勻分佈。此外，熱處理後AB3和AB5的結晶度均有所提升。測得La0.49Ca1.07Mg1.94Ni9合金的儲氫容量在25 ℃為1.34 wt.%。對於AB5，在4 ~ 5 MPa之間出現了另一個平台，其儲氫容量La0.56Ce0.38Ni5減少了0.13 wt.%。 AB3型La-Ca-Mg-Ni和AB5型La0.6Ce0.4Ni5合金混合物在熱處理前的PCI曲線顯示儲氫容量為1.36 wt.%, 0.93 wt.% 解吸容量為1.13 wt.%, 0.78 wt.% 。;The development of materials with high hydrogen storage capacity has thus become important. AB5 alloys are common hydrogen storage material with a reasonable hydrogen storage capacity. However, AB5 alloys consist of a significant portion of rare earth metals (REMs), which are getting more and more expensive. Therefore, AB3 alloys, which use much less REMs but more low-cost metals such as Ca and Mg, may be more cost-effective for hydrogen storage. AB3 alloys have a larger hydrogen storage capacity in addition to the lower working temperature and pressure as compared with the AB5 alloys. Therefore, it is proposed that AB3 alloys can at least partially replace AB5 alloy in some applications. The results in this study show the effect of mixing AB3 and AB5 on the ability to store hydrogen. The main focus of this research is to study the hydrogen storage properties of an AB3 alloy La0.7Ca0.7Mg1.6Ni9 before and after mixing with an AB5 alloy La0.56Ce0.38Ni5; and the effect of heat treatment on these alloys and their composites. Initially, La-Ca-Mg-Ni hydrogen alloy with different elemental ratios was prepared by high-frequency induction heating method, La0.56Ce0.38Ni5 was directly purchased from a Chinese company. Inductively Coupled Plasma (ICP) was used to determine the alloy composition as La0.49Ca1.07Mg1.94Ni9 and La0.56Ce0.38Ni5. To study the effect of heat-treatment on the La-Ca-Mg-Ni/AB5 hydrogen composites, a of AB3 type La–Ca–Mg–Ni-based hydrogen storage alloys have been heat-treated at 800 ℃ for 48 hours under an argon atmosphere. Electron probe microanalysis (EPMA) was used to examine the localized chemical compositions in the samples before and after heat treatment. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to examine the crystal structure and phase changes of the. The X-ray diffraction analysis reveals the presence of two phases in the alloy, namely the FCC (La,Mg)Ni3 phase and the HCP (LaNi5) phase. Finally, the hydrogen storage properties of the samples were studied by a Sivert’s type equipment, and the Pressure-Composition-Isotherms (PCI) curves of the samples were determined. It was found that AB3 obtained shows a flat pressure plateau, thus suggesting a high homogeneity of the alloy prepared using the heat treatment. The hydrogen capacity of pure AB5 and AB5 after heat treatment was found to be 1.4 wt.% and 1.26 wt.% at 25℃, under a hydrogen charging pressure of 5 MPa. In contrast, the PCI curve of the commercial AB5-type La0.6Ce0.4Ni5 hydrogen storage alloy was found to have a higher plateau pressure, with a bigger hysteresis. The hydrogen storage capacity of the sample with 50 wt.% AB3 and 50 wt.% AB5 alloy was found to increased under the same hydrogen charging conditions, indicating the beneficial effect of the blending of the two alloys. In conclusion, AB3-type La-Ca-Mg-Ni alloy was successfully fabricated in this study. The phase structure of FCC & HCP have been verified by XRD and TEM. The result EPMA of AB3 alloy after heat treatment only magnesium aggregated, while the rest of the elements distributed evenly. Besides, the crystallinity of AB3 and AB5 increased after heat treatment. The hydrogen storage capacities of La0.49Ca1.07Mg1.94Ni9 alloy were measured to be 1.34 wt.% at 25 ℃. The hydrogen storage capacities of AB5 before and after heaat treatment La0.6Ce0.4Ni5 1.4 wt. % and 1.26 wt. %. PCI curve of AB3 type La-Ca-Mg-Ni and AB5 type La0.56Ce0.38Ni5 alloy mixture before and after heat treatment rearch 1.36 wt.% and 0.93 wt. %, desorption capacity was 1.13 wt.% and 0.78 wt. %.
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