PSI - Issue 40

E.D. Kurbanova et al. / Procedia Structural Integrity 40 (2022) 251–257 Kurbanova E.D., Polukhin V.A./ / Structural Integrity Procedia 00 (2022) 000 – 000

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friendly engines, where the biggest obstacle hindering the mass market for hydrogen cars is still the lack of infrastructure to ensure a wide supply of hydrogen, and the high cost of producing high-purity hydrogen Dawood et al. (2020), Fontana (2018). However, alternative membrane alloys (based on: Cu, Ni, V, Nb, Zr and Ti) McCluskey et al. (2010), Li (2015), demonstrate strength and kinetic characteristics comparable and even exceeding those based on Pd. One of the first alternative alloys was developed amorphous binary alloys Cu-Zr, VNi15, ternary alloys Cu-Ti-Zr, V-Ni-Ti and alloys based on niobium Nb-Ni-M (M = Ti or Zr), as having good membrane characteristics - kinetics of hydrogen (diffusion and hydrogen permeability), thermal stability and mechanical strength Suryanarayana (2017), Ding et al.(2016). The most promising alloys are titanium-doped binary alloys Nb-Ti-Ni, V Ti-Ni, Ta-Ti-Ni with resistance to hydrogen embrittlement in the temperature range in the range 523-673 K and with cooling control. In addition to amorphous-crystalline alloys, these alloys are also characterized by a dual microstructure represented by primary phases of bcc-Nb / V / Ta with very important secondary eutectic phases B2 TiNi / TiCo, which successfully block hydride formation. Element concentrations are carefully calibrated to the characteristics for each individual alloy, maintaining a balance - excellent permeability and blocking, both intermetallic brittleness and hydride formation, which cause embrittlement and destruction of membranes during a selective hydrogen purification process Suryanarayana (2017). The obtained membrane alloys in the form of discs are tested for strength characteristics - for a fracture, under compression (compressive fracture strength). For the amorphous V85Ni10Ti15 sample with additional doping with zirconium V85Ni10Ti10Zr5 Young's modulus was ~ 2770 MPa, which is significantly higher than for bulk amorphous alloys based on Pd – Cu – Zr (within 1700 – 1900 MPa) and for Pd – Zr – Cu – Hf (2000 – 2500MPa). 2. Amorphous, nano- and crystalline membrane alloys based on Group 5 metals Amorphous alloys Nb 85 Ni 10 Ti 5 and V 85 Ni 10 Ti 15 , Suryanarayana (2017), Ding et al.(2016) obtained by rapid quenching of melts in a chill mold or casting onto a rapidly rotating disk, followed by isothermal treatment at 698 K for 30 minutes in an inert atmosphere. With this heat treatment, the initial amorphous alloys (in the form of rolling disks and strips) are transformed into nanocrystalline alloys. In the same way, amorphous alloys with alloying additions – Mo, W are obtained Liu et al. (2018). The obtained membrane alloys in the form of discs are tested for strength characteristics - for a fracture, under compression (compressive fracture strength). For the amorphous V 85 Ni 10 Ti 15 sample with additional doping with zirconium V 85 Ni 10 Ti 10 Zr 5 Young's modulus was ~ 2770 MPa, which is significantly higher than for bulk amorphous alloys based on Pd – Cu – Zr (within 1700 – 1900 MPa) and for Pd – Zr – Cu – Hf (2000 – 2500 MPa) Tosti (2010). The kinetic characteristics are monitored at a control injection of hydrogen and its flow through the tested membranes, Fig. 1. The applied gas pressure at the inlet is ~ 0.7-1.0 MPa and at a temperature from ~ 673K to 923K. Alloys based on Nb and V are represented by a fluctuating amorphous structure, with alternating high-density icosahedral configurations and their more rarefied boundary junctions, which make up a free volume for more intense diffusion and permeability. Whereas the diffusion of hydrogen through nanocrystalline, and even In an argon atmosphere by the arc melting with subsequent remelting there were obtained the membrane alloys (with the composition (Nb 85 Ni 15 , Nb 85 Ni 10 Ti 5 and V 85 Ni 15 , V 85 Ni 10 Ti 15 ,at.%) until their complete homogenization with of purity - 99.95%. Samples in the form of disks were subjected to rolling and heat treatment, their dimensions after rolling in diameter were 10-12 mm with a thickness of ~ 0.6-0.7 mm. To complete the preparation of functional membranes, the samples on both sides were coated with protective double-sided coatings (against oxidation) by magnetron sputtering of Pd at a temperature of ~ 573 K. Thus, prepared samples with a thickness of about 0.5 ± 0.01 mm were subjected to heat treatment for 3.6 s at 1223 K under vacuum conditions. Thus prepared samples with a thi ckness of about 0.5 ± 0.01 mm were subjected to heat treatment for 3.6 s at 1223 K under vacuum conditions Kozhakhmetov et al. (2015) Then the finished membranes were tested for strength, thermal stability, permeability and diffusion rate. Evaluation of the released hydrogen was also carried out. Then the samples were observated (X ray - XDR) and the changes in microstructures were recorded under the influence of hydrogen. Figure 1 shows schematically a cycle of obtaining ultrapure hydrogen from a mixture of gases and H -generation of a stream using a membrane technology.