Hydrogen Permeation Properties Research Articles

Optimizing hydrogen permeation properties of WS2-Ni composite coatings on pipeline steel for improved hydrogen protection

Tungsten disulfide (WS2) has broad applications due to its unique molecular structure and outstanding physicochemical properties. In particular, the physical barrier properties of WS2 make it suitable to act as barriers against hydrogen. Herein, WS2-Ni composite coatings are prepared by electrodeposition to mitigate hydrogen-induced damage of X70 pipeline steel. The influence of the WS2 concentration on the hydrogen resistance of coating is assessed by electrochemical hydrogen permeation test, hydrogen adsorption simulation, slow strain rate tensile test (SSRT), and fracture analysis. As the WS2 concentration increases, the distributions of WS2 in the coatings transition from sparse to uniform and then agglomeration, while the grain size of Ni decreases initially and then decreases. These microstructural changes impact the hydrogen adsorption sites and diffusion paths, leading to a non-linear relationship between the hydrogen permeation resistance and WS2 concentration. This similar concentration dependence is also observed from the hydrogen embrittlement (HE) resistance of coatings, suggesting that enhancing the hydrogen permeation resistance can improve the HE resistance. This study highlights the great potential of WS2 as an effective barrier against hydrogen permeation, and the results provide insights into the hydrogen protection mechanism of pipeline steel.

Enhancement for hydrogen transport properties by tailoring lattice matching in V-Pd-Fe ternary alloy membrane

V-based alloy membranes have huge potential for hydrogen separation and purification due to their higher hydrogen permeability, but suffer from hydrogen embrittlement. To address this matter, Pd and Fe have been chosen as alloying additions in V-based membranes to inhibit hydrogen embrittlement and maintain high hydrogen permeation performance based on the lattice-matching strategy. The phase structure, composition, microstructure and hydrogen permeation properties of V-Pd-Fe ternary alloy are investigated systematically, and the V-Fe and V-Pd binary alloys are presented for comparison. The results show that the prepared V-Pd-Fe ternary can match almost perfectly with pure V in lattice constants. Attributing to the lattice-matching strategy, the V-Pd-Fe ternary alloy exhibits more excellent hydrogen permeable properties than that of V-Fe and V-Pd binary alloys. The reduction of hydrogen embrittlement is ascribed to the lower hydrogen solubility that induced by the lattice distortion and electronegativity of Fe and Pd. Meanwhile, the manipulated lattice constant that parallel to pure V maintains high hydrogen permeation performance. Additionally, the designed ternary V87.8Pd8Fe4.2 alloy exhibits exceptional long-term hydrogen permeation stability at 573 and 623 K, and hydrogen flux gradually decreases at 673 and 723 K is observed due to the interdiffusion between Pd film and V87.8Pd8Fe4.2 substrate and defects in the Pd coating. This study offers new scenario and method for optimized hydrogen permeable properties and restrains hydrogen embrittlement in the alloy membrane.

Effect of hydrogen permeation and operating parameters on thermochemical performance of solar-driven steam methane reforming membrane reactor

When the steam methane reforming membrane reactor is coupled with trough solar collector to achieve solar thermochemical energy storage, the dimension of the membrane reactor is enlarged and the catalyst filling amount increases dramatically. As a results, the hydrogen permeation property should be well addressed to match the permeation and the reaction characteristics for a better energy storage performance. In the present paper, the effect of hydrogen permeation, including the effective permeation area and the membrane permeance was investigated by numerical simulations. Results show that the sensitivity factors of the membrane surface area on CH4 conversion, H2 yield and H2 recovery are 0.379, 0.325 and 2.196 respectively while that of membrane permeance are 0.007, 0.009 and 0.488 respectively. This indicates that influence of membrane surface area is more remarkable and H2 recovery is the most sensitive to the hydrogen permeation. The reactor with a membrane tube diameter of 50 mm and a permeance of 1.07 × 10−2 mol/(m2·s·Pa0.62) can achieve best reaction performance. Besides the reaction performance, a solar thermochemical system is proposed and a solar-to-fuel efficiency is defined to evaluate the thermochemical performance. Again the aforementioned reactor has the highest solar-to-fuel efficiency which can exceed 70 %. Furthermore, for a better thermochemical performance, lower inlet mass flow rate and higher inlet temperature are recommended, but too small or too high values should be avoided to maintain the operating temperature of the membrane. A suitable combination of pressures in the reaction side and the permeating side is also suggested. The results of the present paper reveal the role of hydrogen permeation and helps the reactor design.

The Synergistic Effect of Carbon Black/Carbon Nanotube Hybrid Fillers on the Physical and Mechanical Properties of EPDM Composites after Exposure to High-Pressure Hydrogen Gas.

This study investigated the synergistic effect of carbon black/multi-wall carbon nanotube (CB/MWCNT) hybrid fillers on the physical and mechanical properties of Ethylene propylene diene rubber (EPDM) composites after exposure to high-pressure hydrogen gas. The EPDM/CB/CNT hybrid composites were prepared by using the EPDM/MWCNT master batch (MB) with 10 phr CNTs to enhance the dispersion of CNTs in hybrid composites. The investigation included a detailed analysis of cure characteristics, crosslink density, Payne effect, mechanical properties, and hydrogen permeation properties. After exposure to 96.3 MPa hydrogen gas, the hydrogen uptake and the change in volume and mechanical properties of the composites were assessed. We found that as the MWCNT volume fraction in fillers increased, the crosslink density, filler-filler interaction, and modulus of hybrid composites increased. The hydrogen uptake and the solubility of the composites decreased with an increasing MWCNT volume fraction in fillers. Moreover, after exposure to hydrogen gas, the change in volume and mechanical properties exhibited a diminishing trend with a higher MWCNT volume fraction. We conclude that the hybridization of CB and CNTs formed strong filler-filler networks in hybrid composites, consequently reinforcing the EPDM composites and enhancing the barrier properties of hydrogen gas.

Improved High-Temperature Stability and Hydrogen Penetration through a Pd/Ta Composite Membrane with a TaTiNbZr Intermediate Layer

In the hydrogen separation membrane, a dense TaTiNbZr amorphous layer was prepared between Pd and Ta to form a Pd/TaTiNbZr/Ta membrane system to prevent the reaction between Pd and Ta at high temperatures. The structural and chemical stability of the Pd/TaTiNbZr/Ta film system at high temperatures were investigated by annealing at 600 °C for 24 h. The high-temperature hydrogen permeation properties of the Pd/TaTiNbZr/Ta film systems were investigated by hydrogen permeation experiments at 600 °C after heat treatment for 6 h. The TaTiNbZr layer was significantly hydrogen-permeable. With the increase in the thickness of the barrier layer, the hydrogen permeability of Pd/TaTiNbZr/Ta decreased, but its hydrogen permeation flux was smaller than that of the highest value of Pd/Ta when it reached the steady state. The presence of the TaTiNbZr layer effectively blocks the interdiffusion between Pd and Ta to form TaPd3, improving the sustained working ability of the Pd/TaTiNbZr/Ta membrane system. The results show that TaTiNbZr is a candidate material for the intermediate layer to improve the high-temperature stability of metal-composite hydrogen separation membranes.

Effect of temperature, air exposure and gas mixture on Pd82–Ag15–Y3 membrane for hydrogen separation

Material characterization, hydrogen permeation, and separation properties of a novel ternary Pd82Ag15Y3 membrane were evaluated by feeding single gases and several mixtures at temperature and pressure ranges of 300–600 °C and 1.0–3.0 bar (abs), respectively. The Pd82–Ag15–Y3 membrane was prepared by cold rolling and was characterized by ∼38 μm of thickness. When exposed to air at different temperature and constant pressure of 1 bar, the membrane showed good thermal and chemical stability. In particular, its surface area increased from 615 μm2 at 25 °C to 685 μm2 at 500 °C indicating a potential improvement of hydrogen permeation. However, several agglomerates consisting of metal oxides were formed on the surface at the highest temperature. The temperature was -then- kept constant at 400 °C and the pressure was varied to analyze the effects of singles gases and several mixtures on the hydrogen permeation characteristics. When exposed to pure gases, such as H2 and N2, the membrane showed an H2 permeability of 9.1 × 10−11 mol m−1 s−1.Pa−0.9 and “n” value of 0.9 due to the presence of Y, while no N2 was detected in the permeate stream, respectively. So, the membrane was considered to be completely selective towards H2 permeation. When mixtures were used, the hydrogen permeation decreased by its original value due to the presence of other gases, such as N2, CH4, CO2 and CO. The presence of CO particularly affected the H2 permeating flux due to the competitive adsorption of both gases on the Pd-alloy surface. Finally, the Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscope (AFM) and X-ray diffraction (XRD) analysis were performed to observe any changes in the surface and structure of pristine and used membrane.

Electrochemical Evaluation of Hydrogen Permeation through Iron Sheets

Devanathan-Stachurski or H cell is successfully used to the evaluation of hydrogen permeation in sheets or membranes. H cell consists of two electrochemical compartments separated by a sheet which acts as working electrode (WE) in both cells. This setup allows the generation of hydrogen in the charging cell, applying a controlled potential or constant current. It diffuses though the sample and is electrochemically detected in the oxidation compartment where the hydrogen gas is oxidized applying a constant potential [1]. The anodic current is directly proportional to the amount of hydrogen penetrating through the membrane with time. As small amounts of hydrogen pass through the membrane, a very sensitive potentiostat is required for its detection. In addition, since the two electrochemical cells use the same WE, two equipments with floating mode with galvanostatic isolation should be used.Taking into account the instrumental requirements, the study of the hydrogen permeation properties of different iron sheets have been analyzed in this work. Different electrochemical profiles are obtained depending on the sample (Figure 1): sample 1 (red line) exhibits a larger diffusivity of the hydrogen due to the higher current recorded, while sample 2 (blue line) not only shows lower current but also shows a delay in the hydrogen transport due to its lower permeability. The absorption of hydrogen by ferrous metals is a serious problem because the hydrogen embrittlement can produce modifications of the mechanical properties of the material with occasional stress corrosion cracking.Figure 1. Hydrogen transients obtained using two different iron samples.

Quaternary Nb-Hf-Co-Fe alloy with superior hydrogen permeation properties over a wide temperature range

Group 5 metals and their alloys are expected to become a new generation of hydrogen-permeable membranes to replace commercial palladium-based alloys. Recently, we synthesized a new Nb-Hf-Co alloy hydrogen permeation membrane, and the Nb30Hf35Co35 alloy has good mechanical properties and permeability. However, the development of alloys with higher hydrogen permeability is a challenge for these Nb-based membranes. To this end, Nb30Hf35Co35−xFex (0 <x < 35) alloys were developed and their microstructure and hydrogen permeation properties were systematically studied by means of SEM, XRD and TEM, among other techniques. When the Fe content is lower than 10 at%, Nb30Hf35Co35−xFex alloys are composed completely of a eutectic structure. With increasing Fe content, changes in microstructure and constituent phases are observed. In particular, a large amount of new impurity phases (Hf2Fe, Fe2Nb, FeNb and Fe0.7Hf0.3) is formed when the Fe content in the alloys is higher than 20 at%. With these changes, the hydrogen permeability (Φ) of these alloys first increases and then decreases. The Nb30Hf35Co30Fe5 alloy exhibits the largest hydrogen permeability at 673 K, at 3.41 × 10−8 mol H2 m−1 s−1 Pa−0.5, or 2.2 times that of palladium metal under the same conditions. The increase in the Φ value is mainly due to the increase in hydrogen diffusion coefficient (K) rather than hydrogen solubility (D). The present work demonstrates that Nb-Hf-Co-Fe quaternary alloys are expected to become a more promising hydrogen permeable material compared with traditional ternary alloys.

Effect of the High-Pressure Hydrogen Gas Exposure in the Silica-Filled EPDM Sealing Composites with Different Silica Content.

With the increasing interest in hydrogen energy, the stability of hydrogen storage facilities and components is emphasized. In this study, we analyzed the effect of high-pressure hydrogen gas treatment in silica-filled EPDM composites with different silica contents. In detail, cure characteristics, crosslink density, mechanical properties, and hydrogen permeation properties were investigated. Results showed that material volume, remaining hydrogen content, and mechanical properties were changed after 96.3 MPa hydrogen gas exposure. With an increase in the silica content, the crosslink density and mechanical properties increased, but hydrogen permeability was decreased. After treatment, high-silica-content composites showed lower volume change than low-silica-content composites. The crack damage due to the decompression caused a decrease in mechanical properties, but high silica content can inhibit the reduction in mechanical properties. In particular, EPDM/silica composites with a silica content of above 60 phr exhibited excellent resistance to hydrogen gas, as no change in their physical and mechanical properties was observed.

A Quantified Study of the Resistance of Duplex Stainless Steels to HISC: Part 2–Significance of the Hydrogen Permeation Properties and Severity of Stress Raisers on Hydrogen Transport and Cracking

The quantified microstructural analysis performed on a wrought and a hot isostatically pressed UNS S31803 duplex stainless steel (DSS) in the Part 1 publication of this study established the significance of the three-dimensional (3D) distribution and morphology/geometry of the ferrite and austenite phases on hydrogen transport through two DSS product forms (see Blanchard, et al., Corrosion 78, 3 [2022]: p. 249–257). This paper is a follow-up to Part 1 and focuses on the role of the other two key, interrelated components of hydrogen-induced stress cracking (HISC): stress/strain and hydrogen. For this purpose, experimental hydrogen permeation measurements, and environmental fracture toughness testing (i.e., J R-curve testing) using conventional and nonstandard single-edge notched bend test specimens were used. These particularly enabled interpretation of the hydrogen permeation and transport test data, and evaluation of suitability of environmental fracture toughness test methods for the assessment of resistance to HISC in DSSs. The latter is discussed, both from laboratory and component integrity perspectives, in the context of the findings from the 3D microstructural characterization of the two phases, the role of stress raisers and their severity, and hydrogen transport through the bulk and from the surface.

Comparison of Hydrogen Permeation and Structural Properties of a Microporous Silica Membrane and a Dense Bace0.9y0.1o3-Δ (Bcy) Perovskite Membrane

Comparison of Hydrogen Permeation and Structural Properties of a Microporous Silica Membrane and a Dense Bace0.9y0.1o3-Δ (Bcy) Perovskite Membrane

Hydrogen Permeation Property of Bulk Cementite

This study investigated the hydrogen permeation property of cementite by fabricating bulk cementite sample using the process combining the mechanical ball milling and subsequent pulse current sintering. The bulk cementite sample having a 96 vol% of cementite was successfully fabricated. The prepared bulk cementite showed no signal of hydrogen permeation during the 3.5 day of electrochemical hydrogen permeation test. The morphology of blister formed in the sample indicated that diffusion coefficient of hydrogen in cementite is very small.

Effect of strain ratio on hydrogen permeability properties of low carbon enamel steel

In this study, the effect of varying strain levels on hydrogen permeability properties were investigated. Distinct strain levels (10% and 40%) were carried out on the deep drawing test samples by using Marciniak die to simulate the forming process. Amount of strain on deep drawn material was calculated by GOM’s ARAMIS 3D deformation measurement system. Hydrogen diffusion coefficient and permeation time were calculated by using Helios II system. Light optical microscope (LOM) and scanning electron microscopy (SEM) were used for microstructure characterization. Automated inclusion/precipitation analysis was performed by Thermoscientific Explorer-4. By this study, it is aimed to understand the hydrogen permeation properties of ultra-low carbon IF steel material with varying strain values. Finally, it was determined that number of inclusion/precipitation per mm2 was significantly increased as a function of strain ratio, which improves hydrogen permeation properties.

Evaluation techniques of hydrogen permeation in sealing rubber materials

Three techniques for determining the hydrogen permeation properties of rubber samples were developed based on the volumetric and gravimetric measurements of released H2 gas after sample decompression. These methods include gas chromatography (GC) by thermal desorption analysis (TDA), volumetric collection (VC) measurement of hydrogen by graduated cylinder and gravimetric (GM) measurement by electronic balance. By measuring the released hydrogen against elapsed time after the decompression of pressure, the charging amount (C0) and diffusivity (D) were obtained with the developed diffusion analysis program. From these values, the solubility (S) and permeability (P) of polymers were evaluated through the relations of Henry's law andP=SD, respectively. The developed techniques were applied to three kinds of spherically shaped sealing rubber materials. D, S and P were analyzed as a function of pressure. The transport behaviors obtained in the three methods are discussed and compared with the characteristics of each measuring technique. The correlations between transport parameters and carbon black filler or density are discussed.

Design and properties of FeAl/Al2O3/TiO2 composite tritium-resistant coating prepared through pack cementation and sol–gel method

Structural steel materials exist in tritium breeding blankets and auxiliary tritium handling systems in fusion reactors. Applying a tritium permeation barrier coating on the surface of the structural material is necessary to prevent material corrosion and embrittlement. In this study, FeAl/Al2O3/TiO2 composite tritium-resistant coating on 316 L stainless steel substrate was successfully prepared by pack cementation and sol–gel method. The surface and cross-section morphologies of the composite coatings were systematically studied. The hydrogen permeation properties and adhesion between the different composite coatings were investigated. Results show that the FeAl/Al2O3/TiO2 composite tritium resistant coating is uniform, dense, and preferably connected to the substrate without defects such as cracks and pores. Compared with FeAl/Al2O3 coating, FeAl/Al2O3/TiO2 coating has better bonding strength, toughness, and ductility. Hydrogen permeation test shows that the design of the FeAl/Al2O3/TiO2 composite coating improves the hydrogen resistance of the coating at room temperature.

Design of hydrogen separatinwg Nb-Ti-Fe membranes with high permeability and low cost

Nowadays, group 5B (Nb-, V-, and Ta-based) alloys are considered prospective candidates to replace commercial Pd-based hydrogen permeation membranes. In recent years, the focus of research efforts towards these metal membranes has been the development of robust/cheaper alloys and the exploration of related phase diagrams. To address this challenge, the phase diagram and solidification path of the Nb-Ti-Fe alloy system have been investigated within the CALPHAD (CALculation of PHAse Diagrams) approach by combining available experimental data. On this basis, Nb-Ti-Fe multi-phase hydrogen-permeable alloys have been designed and fabricated, and their microstructure, hydrogen permeability, and hydrogen embrittlement (HE) resistance were evaluated. The results obtained show four ternary invariant reactions and five phase regions in the liquidus projection, where the compositional region suitable for hydrogen permeation has been established successfully. Small variations in alloy composition (e.g. Nb or Ti/Fe ratios) can lead to large changes in hydrogen permeation properties. This is attributed to the TiFe phase in the eutectic structure transition from a continuous thin layer to discontinuous granules. In particular, Nb5Ti60Fe35 shows the highest permeability at 673 K, 3.82 × 10−8 mol H2 m−1 s−1 Pa−1/2, which, heretofore, is the highest value reported in this alloy system.

Hydrogen Permeation Property and Hydrogen Embrittlement Susceptibility of Pipeline Steel with Oxide Film

In this study, the oxide film on X80 steel was fabricated to decrease hydrogen embrittlement of pipeline steel. The microstructures and mechanical properties in 10MPa hydrogen gas and hydrogen permeation properties were investigated. The phase structure of oxide film was mainly composed of Fe2O3. With the increasing of oxidation temperature, surface oxygen content improves gradually. Oxide film plays an important role in resisting hydrogen penetrating. Hydrogen diffusion coefficient decreases from 38.81☓10-7cm2s-1 to 1.26☓10-7 cm2s-1 for oxidation at 450 ℃. The plastic deformation increases obviously after oxidation. HEI decreases from 40.96% to 11.61% for oxidation at 450 ℃.

Effects of doping with a third element (Pd, Ru, Ta) on the structure and hydrogen permeation properties of V–10Mo solid solutions

Alloying is an effective method for improving the resistance of V metals to hydrogen embrittlement. The effects of the doping with a third element (Pd, Ru, Ta) on the structure and hydrogen permeation properties of V–10Mo solid solutions have been investigated in this study. As-prepared V–5Mo-5TM (TM = Mo, Pd, Ru, Ta) alloy samples composed of V-based solid solution with a bcc structure are hydrogenated into their corresponding solid solutions (α-phase). Structural changes caused by TM-doping have notable effects on the hydrogen permeation properties (particularly the hydrogen solubility) of V–10Mo alloy, and the ability of the doping element in decreasing the hydrogen solubility of the V–10Mo alloy follows the sequence: Pd > Ru > Ta. Their doping causes a slight decrease in the hydrogen diffusion coefficient as well as an increase in the Vickers hardness of the resulting alloys. This work demonstrates that the mechanical property of V–10Mo alloy can be improved via suitable structure control caused by alloying it with an appropriate element. In addition, this approach might be suitable for improving properties of other relevant binary alloys.

Improving hydrogen permeation and interface property of ceramic-supported graphene oxide membrane via embedding of silicalite-1 zeolite into Al2O3 hollow fiber

Graphene oxide (GO)-based membranes have previously demonstrated great gaseous molecular separation potential. However, defect-free GO-based laminar membrane presents major challenge given the difficulty to deposit configured GO film onto the porous ceramic support. This work reports single-step synthesis of a molecular sieving GO membrane film on top of silicalite-1 (Sil-1)-modified alumina (Al2O3) (Sil-1-Al2O3) hollow fiber. The critical Sil-1 content in the support is 2 wt%, above which there is marginal improvement of the interfacial adhesion, d-spacing, and hydrogen permeance. Binary gas permeation experiments on GO/2 wt% Sil-1-Al2O3 membrane revealed parallel increase of H2 and N2 permeance with temperature rise and decrease in H2 selectivity at higher temperatures. The operational stability of the composite membrane was demonstrated by stable H2 permeance (1.22 · 10−7 mol m−2 s−1 Pa−1) and selectivity (40.7) over 240-h operation at 20 °C, and maintained consistently following 210-h operation at 100 °C. Modeling study revealed major driving force contribution near the fiber inlet to increase the overall membrane H2 permeance.

Hydrogen Permeation of Multi-Layered-Coatings

Using a substrate of AISI 316L austenitic stainless steel, which is used for components in high-pressure hydrogen systems, the hydrogen barrier properties of samples with single-layer coatings of TiC, TiN, and TiAlN as well as a multi-layered coating of TiAlN and TiMoN were evaluated. The ion plating method was used, and coating thicknesses of 2.0–2.6 μm were obtained. Hydrogen permeation tests were carried out under a differential hydrogen pressure of 400 kPa and at a temperature between 573 and 773 K, and the quantities of hydrogen that permeated the samples were measured. This study aimed at elucidating the relationship between the microstructures of the coatings and the hydrogen permeation properties. Coatings of TiC, TiN, TiAlN, and TiAlN/TiMoN facilitated reductions of the hydrogen permeabilities to 1/100 or less of that of the uncoated substrate. The samples coated with TiN and TiC that developed columnar crystals vertical to the substrate exhibited higher hydrogen permeabilities. The experiment confirmed that the coatings composed of fine crystal grains were highly effective as hydrogen barriers, and that this barrier property became even more efficient if multiple layers of the coatings were applied. The crystal grain boundaries of the coating and interfaces of each film in a multi-layered coating may serve as hydrogen trapping sites. We speculate that fine crystal structures with multiple crystal grain boundaries and multi-layered coating interfaces will contribute to the development of hydrogen barriers.