Transport of hydrogen and deuterium in 316LN stainless steel over a wide temperature range for nuclear hydrogen and nuclear fusion applications

The permeation of hydrogen and deuterium through 316LN stainless steel (316LN SS) was investigated over a wide temperature range of 300–850 °C for nuclear hydrogen and nuclear fusion applications. We presented the first complete datasets of permeability Φ, diffusivity D, and solubility S for both hydrogen (H) and deuterium (D) in 316LN SS. Φ_H and Φ_D were 3.47 × 10⁻⁷exp(−66.6 × 10³/RT) and 2.71 × 10⁻⁷exp(−67.5 × 10³/RT) mol·m⁻¹ s⁻¹ Pa^−0.5, respectively. D_H and D_D were 15.9 × 10⁻⁷exp(−56.5 × 10³/RT) and 13.8 × 10⁻⁷exp(−56.8 × 10³/RT) m²∙s⁻¹, respectively. The estimated isotope effect ratios of Φ_H/Φ_D, D_H/D_D, and S_H/S_D were ~1.4, ~1.2, and ~1.2, respectively. The previously reported results for 316LN SS were extrapolated to the temperature range used herein and were compared with the results of this study. Although some discrepancies were observed between the results of this study and previous studies, they were within the acceptable scattering range.     

Fabrication,characterization, and application of palladium composite membrane on porous stainless steel substrate with NaY zeolite as an intermediate layer for hydrogen purification

Palladium composite membrane with excellent stability was successfully prepared using the electroless plating (ELP) route on a porous stainless steel (PSS) support for hydrogen separation. In order to modify the average pore size of PSS support and to prevent inter-metallic diffusion, the NaY zeolite layer was coated on the PSS support with the seeding and secondary growth method. A high-temperature membrane module was designed by Solid work software and fabricated from 316 L stainless steel with a knife-edge seal. The microstructures and morphologies of the samples were analyzed using XRD, BET, AFM, FESEM and EDX techniques. Permeation experiments were carried out with binary mixtures of H₂/N₂ with various ratios (90/10, 75/25 and 50/50) and pure H₂ and N₂ at different temperatures (350, 400 and 450 °C) and feed pressures (200–400 kPa). Hydrogen permeation tests showed that the membrane with a thickness of about 7 μm had a hydrogen permeance of 6.2 × 10⁻⁴ mol m⁻² s⁻¹ Pa^−0.5 with an ideal H₂/N₂ selectivity of 736, at 450 °C. In addition, the results of stability tests revealed that the membrane could remain stable during a long-term operation by varying temperature and feed gases.     

Electrochemical study of hydrogen diffusion behavior in Mg2Ni-TYPE hydrogen storage alloy electrodes

Hydrogen diffusion behavior in Mg₂Ni-type hydrogen storage alloy electrodes was characterized by using both potentiostatic polarization method, based on a spherical diffusion model, and electrochemical impedance spectroscopy (EIS) technique. The values of the diffusion coefficients of hydrogen in Mg₂Ni and Mg_1.9V_0.1Ni_0.8Al_0.2 are 1.2×10⁻¹¹ ∼ 1.57×10⁻¹⁰ and 3.1 ∼ 7.6×10⁻⁹ cm²/s, respectively. The values of diffusion coefficients decline notably with the increase in depth of discharge (DOD). The decay rate of diffusion coefficient in Mg₂Ni with DOD is much quicker than that in Mg_1.9V_0.1Ni_0.8Al_0.2. The experimental results suggested that the substitutions of V and Al for Mg and Ni in Mg₂Ni could significantly improve the hydrogen diffusion performance in this alloy and thus substantially increase discharge capacity of the electrode. © 1998 International Association for Hydrogen Energy     

Hydrogen diffusivity in different microstructural components in martensite matrix with retained austenite

We elucidate the hydrogen diffusivity in martensite matrix with retained austenite (RA). Two aspects are focused: effect of microstructure on hydrogen diffusion behavior; hydrogen diffusivity calculation for different microstructural components. Quenched martensite (QM) had the highest effective hydrogen diffusion coefficient because of high dislocation density. Effective hydrogen diffusion coefficient decreased with the increase of intercritical annealing temperature because of decrease in dislocation density and increase of RA. According to the principle of Maxwell-Garnett equation, the hydrogen diffusion coefficient for grain boundary (GB) was 7.99 × 10^?8 m²/s and hydrogen diffusion coefficient of tempered martensite (TM) was 7.84 × 10^?11 m²/s.     

Modeling and numerical simulation of a 5 kg LaNi5-based hydrogen storage reactor with internal conical fins

Hydrogen absorption by ~5 kg LaNi₅ in a metal hydride reactor is simulated. A cylindrical reactor (OD 88.9 mm, Sch- 40s, SS 316) with internal conical copper fins and cooling tubes (1/4^”, SS 316) carrying water at 1 m s⁻¹ and 293 K (inlet) is considered. Designs with 10, 13 and 19 equi-spaced fins and 2, 4 and 6 cooling tubes are explored. Hydrogen (15 atm) is supplied through a coaxial metal filter (OD 12 mm, SS 316). Conical fins offer enhanced heat transfer through higher surface area and funnelling effect for efficient loading of metal hydride powder. 19 fins + 6 tubes design requires 290 and 375 s for 80% and 90% hydrogen saturation level, respectively. The fins near the water inlet regions are more effective as the water temperature is lower in these regions. Trade-off exists between times taken for saturation and the mass of metal hydride.     

Improved hydrogen permeation through thin Pd/Al2O3 composite membranes with graphene oxide as intermediate layer

Here we proposed the decreasing in the roughness of asymmetric alumina (Al₂O₃) hollow fibers by the deposition of a thin graphene oxide (GO) layer. GO coated substrates were then used for palladium (Pd) depositions and the composite membranes were evaluated for hydrogen permeation and hydrogen/nitrogen selectivity. Dip coating of alumina substrates for 45, 75 and 120 s under vacuum reduced the surface mean roughness from 112.6 to 94.0, 87.1 and 62.9 nm, respectively. However, the thicker GO layer (deposited for 120 s) caused membrane peel off from the substrate after Pd deposition. A single Pd layer was properly deposited on the GO coated substrates for 45 s with superior hydrogen permeance of 24 × 10⁻⁷ mol s⁻¹m⁻² Pa⁻¹ at 450 °C and infinite hydrogen/nitrogen selectivity. Activation energy for hydrogen permeation through the Al₂O₃/GO/Pd composite membrane was of 43 kJ mol⁻¹, evidencing predominance of surface rate-limiting mechanisms in hydrogen transport through the submicron-thick Pd membrane.     

Study on the hydrogen barrier performance of the SiOC coating

SiOC coatings were prepared on X70 pipeline steel substrate by a simple dipping method at low temperatures, and their performance of hindering hydrogen penetration was studied through electrochemical hydrogen permeation experiment. The sample thermal-treated at 120 °C achieved a low diffusion coefficient of hydrogen of 8.20 × 10^?9 cm² s^?1, which was nearly three orders of magnitude lower than 3.58 × 10^?6 cm² s^?1 for the X70 steel. This was due to that the amorphous coating did not provide a stable hydrogen diffusion channel, thus limiting hydrogen diffusion. Density functional theory (DFT) calculation further proved that hydrogen moleculars were difficult to be adsorbed at different sites on the surface of the coating.     

Hydrogen embrittlement and hydrogen diffusion behavior in interstitial nitrogen-alloyed austenitic steel

The susceptibility to hydrogen embrittlement and diffusion behavior of hydrogen were evaluated in interstitial nitrogen-alloyed austenitic steel QN1803 and 304 and 316 L stainless steels. The amount of transformed martensite and the activation energy of hydrogen diffusion were revealed via electron backscattering diffraction and thermal desorption spectroscopy. The austenite stability of QN1803 during the deformation process was higher than that of 304 and 316 L. However, the hydrogen content of QN1803 was high because of the small grain size and low activation energy of hydrogen diffusion. For the stable QN1803 and 316 L austenitic steels, martensite had no evident harmful effect because of its discrete distribution. A planar dislocation slip was observed in QN1803 during deformation. Hydrogen charging enhanced dislocation mobility, leading to severe strain localization. Thus, the severe strain in QN1803 promoted microcracking.     

Impact of surface oxide on hydrogen permeability of chromium membranes

Hydrogen permeation through pure and oxidised bulk chromium membranes was measured by the classical gas technique to get insight into oxide as a hydrogen permeation barrier (HPB). An additional palladium-coated reference chromium membrane was tested to avoid the influence of native Cr oxide. Key parameters for Cr permeability: P₀ = 3.23 × 10^?7 mol H₂/s/m/Pa^0.5 and E_a = 0.68 eV and Cr diffusivity D₀ = 9.0 × 10^?5 m²/s and E_a = 0.59 eV. In the sample preparation stage, a thin ～2 nm thick oxide was formed. Additional oxidation in pure oxygen at 400 °C increased the thickness from 20 to 50 nm. At this temperature, its efficiency as HPB was evaluated by comparing permeation rates to the reference chromium membrane. The highest permeation reduction factor of ～3900 corresponded to only a ～28 nm thick Cr oxide layer. Surface morphology and oxide thickness were investigated by SEM, while the thickness and type of chromium oxide by XPS.     

Influence of microstructure on hydrogen trapping and diffusion in a pre-deformed TRIP steel

Austenitic steels are known to exhibit a low hydrogen diffusion coefficient and hence a good resistance to hydrogen embrittlement. Therefore, it is an experimental challenge to investigate their hydrogen diffusion properties. In this study, the electrochemical permeation technique is used to determine the hydrogen diffusion coefficients in different pre-deformed states (φ = 0, 0.32, 0.39, 0.49) of the high-alloy austenitic TRIP steel X3CrMnNiMoN17-8-4 in a temperature range of 323 K–353 K. In combination with microstructural analysis, a correlation between phase transformation from γ-austenite to α′-martensite and dislocation density is shown. As a result of the lattice transformation from fcc to bcc, the diffusion rate of hydrogen is significantly increased (D_{app, φ = 0} = 3.6 × 10^?12 cm² s^?1, D_{app, φ = 0.32} = 1.6 × 10^?11 cm² s^?1at 323 K). With higher degrees of deformation, the dislocation density also increased in the martensite islands, resulting in a degressive growth of the diffusion coefficient (D_{app, φ = 0.39} = 5.3 × 10^?11 cm² s^?1, D_{app, φ = 0.49} = 1.1 × 10^?10 cm² s^?1at 323 K). Moreover, detailed calculations are performed to describe the way of hydrogen trapping and to give a possible mechanism of diffusion.     

Electrochemical and hydrogen evolution behaviour of a novel nano-cobalt/nano-chitosan composite coating on a surgical 316L stainless steel alloy as an implant

Herein, nanocomposite coatings consisting of chitosan (CSNPs) and cobalt nanoparticles (CoNPs) were deposited on bare 316L stainless steel alloy (316L SS) as a bone implant. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) were applied to characterize the morphological and chemical composition of the tested nanocoatings. In-vitro degradation and hydrogen evolution behaviour of the coated samples were examined by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques, in Hank's solution containing of 1 × 10^?3 M calcium hydrogen phosphate drug at pH 7.4 and temperature 37 °C. This drug used as an inhibitor for protecting the alloy surface from the corrosive medium and minimized the hydrogen evolution rate. Results showed that the di-phasic coating (CoNPs-CSNPs) gave the highest electrochemical corrosion resistance with the lowest hydrogen evolution rate in comparison to the monophasic coatings (CS-NPs & Co-NPs). These corrosion results suggested that a CoNPs-CSNPs nanocomposite coating on 316L SS was effective for renewable or functional implants.     

Effect of cyclic plastic deformation on hydrogen diffusion behavior and embrittlement susceptibility of reeling-pipeline steel weldments

The hydrogen embrittlement (HE) susceptibility and hydrogen permeation behavior of reeling-pipeline welded joint with/without cyclic plastic deformation (CPD) were studied using the electrochemical hydrogen charging technique. Results indicated that the surface of welded joint emerged hydrogen-induced damage containing cracks and blisters. The degree of hydrogen-induced damage increased with the increase of hydrogen charging time and current density. When the hydrogen charging current density and time was 50 mA/cm² and 4 h, respectively, the area ratio of hydrogen-induced damage of overall welded joint with CPD process was reduced from 6.61% to 2.28%, and the damage ratio of different sub-zones in welded joint was also decreased. The oxidized inclusions enriching Al–Mg–Ca elements acted as the initiation sites for hydrogen-induced damages. The effective diffusion coefficient of as-welded joint was 2.63 × 10⁻⁶ cm²/s, while that of welded joint with CPD showed a smaller value of 1.36 × 10⁻⁶ cm²/s. The welded joint with CPD process presented better resistance to HE, which was attributed to the increased density of hydrogen traps and the formation of dislocation cells to disperse hydrogen uniformly and reduce the possibility of local accumulation and recombination of diffusible hydrogen. Sub-zones in welded joint without CPD process were considerably more sensitive to hydrogen-induced damage, which indicated the important role of microstructure and dislocation density in HE mechanisms. The order of HE susceptibility from low to high was weld metal, base metal and heat affected zone.     

Effect of residual hydrogen content on the tensile properties and crack propagation behavior of a type 316 stainless steel

The tensile properties and crack propagation rate in a type 316 austenitic stainless steel prepared by vacuum induction melting method with different residual hydrogen contents (1.1–11.5 × 10⁻⁶) were systematically investigated in this research work. The room temperature tensile properties were measured under both regular tensile (12 mm/min) and slow tensile (0.01 mm/min) conditions, and the fracture properties of the tensile fractures with both rates were analyzed. It shows that the hydrogen induced plasticity loss of stainless steel strongly depends on the tensile rate. Under regular tensile condition, there is no plastic loss even when the hydrogen content is up to 11.5 × 10⁻⁶ while in the slow tensile condition, the plastic loss can be clearly identified rising with the increasing H contents. The fatigue crack propagation rate was tested at room temperature, and the crack growth rate formula (Paris) of the 316 stainless steels with varied H contents were obtained. The fatigue crack propagation rate test shows that the crack growth rate of the 316 stainless steel with 8.0–11.5 × 10⁻⁶ hydrogen is significantly higher than that of benchmark steel.     

Notched-tensile properties under high-pressure gaseous hydrogen: Comparison of pipeline steel X70 and austenitic stainless type 304L, 316L steels

The effect of high-pressure gaseous H₂ on the fracture behavior of pipeline steel X70 and austenitic stainless steel type 304L and 316L was investigated by means of notched-tensile tests at 10 MPa H₂ gas and various test speed. The notch tensile strength of pipeline X70 steel and austenitic stainless steels were degraded by gaseous H₂, and the deterioration was accompanied by noticeable changes in fracture morphology. The loss of notch tensile strength of type 316L and X70 steels was comparable, but type 304L was more susceptible to hydrogen embrittlement than the others. In the X70 steel, hydrogen embrittlement increased as test speed decreased until the test speed reached 1.2 × 10^?3 mm/s, but the effect of test speed was not significant in 304L and 316L steels.     

Remarkable isosteric heat of hydrogen adsorption on Cu(I)-exchanged SSZ-39

Hydrogen storage capacity on Cu(I)-exchanged SSZ-39 (AEI), -SSZ-13 (CHA) and Ultra stable-Y (US–Y, FAU) at temperatures between 279 K and 304 K are investigated. The gravimetric hydrogen storage capacity values reaching 83 μmol H₂ g⁻¹ (at 279 K and 1 bar) are found to be comparable with the highest adsorption capacity values reported on metal-organic frameworks. The volumetric hydrogen storage capacity values; on the other hand, are found to be more than three times of those reported on metal-organic frameworks (0.57 g/L on Cu(I)-SSZ-39 at 1 bar and 296 K vs. ca. 0.18 g/L on Co₂(m-dobdc) at 1 bar and 298 K (Kapelewski MT, Runčevski T, Tarver JD, Jiang HZH, Hurst KE, Parilla PA et al. Record High Hydrogen Storage Capacity in the Metal-Organic Framework Ni₂(m-dobdc) at Near-Ambient Temperatures. Chem Mater 2018; 30:8179–89)). The isosteric heat of adsorption values are calculated to be between 80 kJ mol⁻¹ and 49 kJ mol⁻¹ on Cu(I)-SSZ-39 and between 22 kJ mol⁻¹ and 15 kJ mol⁻¹ on Cu(I)-US-Y indicating H₂ adsorption mainly at Cu(I) cations located at the eight-membered rings on Cu(I)-SSZ-39 and at six-membered rings on Cu(I)-US-Y. Hydrogen adsorption experiments performed at 77 K showed higher adsorption capacity values for Cu(I)-SSZ-39 at 1 bar, but Cu(I)-US-Y showed potential for hydrogen storage at higher pressure values.     

Nanocomposite membrane based on SPEEK as a perspectives application in electrochemical hydrogen compressor

Achieving favourable proton exchange membrane characteristics such as proton conduction, mechanical properties and hydrogen crossover is one of the main challenges in development of Electrochemical Hydrogen Compressor (EHC) systems for improving energy consumption. This work demonstrates three different in-house fabricated membranes based on Sulphonated poly (ether-ether ketone, SPEEK). The first membrane is an unmodified membrane ([S70]), second membrane ([S70/HNT15], 15 % wt/wt) was modified with a nanoclay (Halloysite Nanotubes, HNT), and last membrane is Halloysite nanotubes impregnated with Phosphotungstic Acid ([S70/(PWA/HNT30)15]). These membranes show different hydrogen crossover rate, with the [S70] membrane exhibiting 3.873 × 10⁻⁰⁸ mol bar⁻¹s⁻¹cm⁻² whereas the [S70/HNT15] and [S70/(PWA/HNT30)15] nanocomposite membranes show rates of 7.296 × 10⁻¹⁰ and 9.103 × 10⁻¹⁰ mol bar⁻¹ s⁻¹ cm⁻², respectively. Furthermore, unmodified membrane presented quadratic behaviours with increased pressure in cathodic compartment, whereas nanocomposite membranes exhibit a logarithmic behaviour. For another hand, extrapolation data show that unconventional nanocomposites membranes present a low energy consumption at high pressures, which is promising for potential candidates for use in EHC systems.     

Analysis and modelling of microwave plasma hydrogen production utilizing water vapor and tungsten electrodes

In this study, hydrogen production via microwave plasma is investigated, analyzed and simulated in a novel way for practical applications. The water vapor when in proximity of a tungsten electrode is modeled for the generation of hydrogen gas. A numerical simulation study is performed using plasma and electromagnetic wave COMSOL modules to analyze the plasmolysis of water vapor within a vacuum concealed reaction vessel entailing a tungsten electrode. A kinetic model is therefore developed to represent the reaction mechanisms and interactions between the species within the plasmolysis reactor. The dynamic results of electron density, electron temperature, plasma rate, and species interactions are extracted through the kinetic model. Within the time domain of 10⁻¹⁶ to 10⁻¹⁴ s, the hydrogen concentration is found to increase to 4.5815 $\times$ 10⁻¹¹ mol/m³ with a corresponding decrease in water vapor concentration of 1.782 $\times$ 10⁻⁸ mol/m³, respectively. The dynamic variations in the concentrations of other dissociated species are investigated across the geometry of the reaction domain studied, and it is therefore concluded that the tip of the electrode entails the highest species concentrations.     

Hydrogen dispersion phenomenon in nominally closed spaces

The hydrogen dispersion phenomenon in an enclosure depends on the ratio of the gas buoyancy-induced momentum and diffusive motions. Random diffusive motions of individual gas particles become dominative when the release momentum is low, and a uniform hydrogen concentration appears in the enclosure instead of the gas cumulation below the ceiling. The expected hydrogen behavior could be projected by the Froude number, which value ~1 predicts a decline of buoyancy. This paper justifies this hypothesis by demonstrating full-scale experimental results of hydrogen dispersion within a confined space under six different release variations. During the experiments, hydrogen was released into the test room of 60 m³ volume in two methods: through a nozzle and through 21 points evenly distributed on the emission box cover (multi-point release). Each release method was tested with three volume flow rates (3.2 × 10⁻³ m³/s, 1.6 × 10⁻³ m³/s, 3.3 × 10⁻⁴ m³/s). The tests confirm the decrease of hydrogen buoyancy and its stratification tendencies when the Mach, Reynolds, and Froud number values decrease. Because the hydrogen dispersion phenomenon would impact fire and explosive hazards, the presented experimental results could help fire protection systems be in an enclosure designed, allowing their effectiveness optimization.     

Hydrogen diffusion through Ru thin films

In this paper, an experimental measurement of the diffusion constant of hydrogen in ruthenium is presented. By using a hydrogen indicative Y layer, placed under the Ru layer, the hydrogen flux through Ru was obtained by measuring the optical changes in the Y layer. We use optical transmission measurements to obtain the hydrogenation rate of Y in a temperature range from room temperature to 100 °C. We show that the measured hydrogenation rate is limited mainly by the hydrogen diffusion in Ru. These measurements were used to estimate the diffusion coefficient, D, and activation energy of hydrogen diffusion in Ru thin films to be D = 5.9 × 10⁻¹⁴ m²/s ∙ exp (-0.33 eV/k_Bτ), with k_B the Boltzmann constant and τ the temperature.     

Computational analysis of geometrical factors affecting experimental data extracted from hydrogen permeation tests: II – Consequences of trapping and an oxide layer

Although electrochemical permeation tests are used to determine the diffusion coefficients of hydrogen through metals, these measures are affected by various phenomena such as trapping or surface states. In this work, we analyzed the combined effects on diffusion of hydrogen trapping and the presence of an oxide layer at the exit side of the material. We numerically simulated the diffusion of hydrogen through a 1 mm thick martensitic steel membrane, using Finite Elements Method. Trapping densities are taken between 10⁻⁴ and 100 mol/m³, for an oxide layer 5 nm thick. We studied oxide layers with hydrogen diffusion coefficients between 10⁻²¹ and 10⁻¹⁰ m²/s. It appears that the diffusion is withheld by trapping and the oxide layer. However both parameters exhibit opposite effects on hydrogen subsurface concentrations; analytical equations have been proposed to correct the experimental results obtained by electrochemical permeation tests, using the material properties. It appears that the ratios between the membrane and the oxide diffusion coefficients and thicknesses guide the influence of trapping and the oxide layer.