Hydrogen desorption/absorption properties of the extensively cold rolled β Ti–40Nb alloy |
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| Affiliation: | 1. Universidade Federal de São Carlos (UFSCar), Departamento de Engenharia de Materiais, Rodovia Washington Luiz, km 235, CEP: 13565 – 905, São Carlos, SP, Brazil;2. Instituto de Pesquisas Energéticas e Nucleares (IPEN), Av. Lineu Prestes 2242, Cidade Universitária, CEP: 05508-000, São Paulo, SP, Brazil;1. Department of Hydraulic and Sanitation, University of São Paulo, Av. Trabalhador Sãocarlense, 400, Centro, CEP 13566-590, São Carlos, SP, Brazil;2. Department of Chemical Engineering, Federal University of São Carlos, Rod. Washington Luis, Km 235, CEP 13565-905, São Carlos, SP, Brazil;1. School of the Environment and Safety Engineering, Jiangsu University, China;2. Institute of Green Chemistry and Chemical Technology, School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, 212013, PR China;3. Key Laboratory of Preparation and Applications of Environmental Friendly Materials, Jilin Normal University, Ministry of Education, Changchun, 130103, PR China;1. School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China;2. School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China;3. Beijing Key Laboratory of Powertrain for New Energy Vehicle, Beijing Jiaotong University, Beijing 100044, China;1. State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, 250353, Shandong, PR China;2. Department of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, PR China;3. School of Electronic and Information Engineering (Department of Physics), Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, PR China;4. State Key Lab Plateau Ecology and Agriculture, Qinghai University, Xining, 810016, Qinghai, PR China |
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| Abstract: | β Ti–Nb BCC alloys are potential materials for hydrogen storage in the solid state. Since these alloys present exceptional formability, they can be processed by extensive cold rolling (ECR), which can improve hydrogen sorption properties. This work investigated the effects of ECR accomplished under an inert atmosphere on H2 sorption properties of the arc melted and rapidly solidified β Ti40Nb alloy. Samples were crushed in a rolling mill producing slightly deformed pieces within the millimeter range size, which were processed by ECR with 40 or 80 passes. Part of undeformed fragments was used for comparison purposes. All samples were characterized by scanning electron microscopy, x-ray diffractometry, energy-dispersive spectroscopy, hydrogen volumetry, and differential scanning calorimetry. After ECR, samples deformed with 40 passes were formed by thick sheets, while several thin layers composed the specimens after 80 passages. Furthermore, deformation of β Ti–40Nb alloys synthesized samples containing a high density of crystalline defects, cracks, and stored strain energy that increased with the deformation amount and proportionally helped to overcome the diffusion's control mechanisms, thus improving kinetic behaviors at low temperature. Such an improvement was also correlated to the synergetic effect of resulting features after deformation and thickness of stacked layers in the different deformation conditions. At the room temperature, samples deformed with 80 passes absorbed ～2.0 wt% of H2 after 15 min, while samples deformed with 40 passes absorbed ～1.8 wt% during 2 h, excellent results if compared with undeformed samples hydrogenated at 300 °C that acquired a capacity of ～1.7 wt% after 2 h. The hydrogen desorption evolved in the same way as for absorption regarding the deformation amount, which also influenced desorption temperatures that were reduced from ～270 °C, observed for the undeformed and samples deformed with 40 passes, to ～220 °C, for specimens rolled with 80 passes. No significant loss in hydrogen capacity was observed in the cold rolled samples. |
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| Keywords: | β Ti–Nb alloy Extensive cold rolling Hydrogenation Solid-state hydrogen storage |
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