Hydrogen Absorption Research Articles

Synthesis of Mg2FeH6 by High‐Temperature High‐Pressure Reactive Planetary Ball Milling

Herein, a new approach for the synthesis of metal hydrides using simultaneous high‐temperature and high‐pressure reactive ball milling is demonstrated by preparing ternary magnesium iron hydride. The novelty and uniqueness of this technique are based on its integration of a specially designed and manufactured milling vial, allowing synthesis at controlled elevated temperatures (room temperature [RT]–400 °C) and pressures up to 100 bar. A Mg and Fe (2:1) mixture is used as a substrate for Mg2FeH6 synthesis. The effects of temperature on the synthesis kinetics and their outcomes are examined. An increase in the temperature accelerates the kinetics of hydrogen absorption for MgH2, while Mg2FeH6 formation is observed only above 250 °C. Increasing the reaction temperature not only causes magnesium particle refinement due to the hydrogenation and formation of magnesium hydrides but also leads to the agglomeration of iron caused by plastification due to a lack of strain hardening. The maximum conversion to Mg2FeH6 is observed for the sample premilled at RT. In this work, it is revealed that additional physical variables, e.g., pressure, temperature, time, and milling speed, during mechanochemical synthesis and material properties, need to be evaluated and considered to improve the reaction kinetics and yield of the synthesis.

Impact of the Delay Period between Electrochemical Hydrogen Charging and Tensile Testing on the Mechanical Properties of Mild Steel

With escalating global regulatory pressure for countries to adhere to emission laws, repurposing existing natural gas pipelines for hydrogen-based commodities stands to be an economical solution. However, the effects of hydrogen embrittlement must be thoroughly considered for this application to avoid the unexpected catastrophic failure of these pipelines. The literature proposes several physicochemical embrittlement models. This paper reports one aspect of hydrogen embrittlement that remains to be quantified: the recovery of ductility (embrittlement) of mild steel specimens subjected to artificially accelerated hydrogen absorption via electrochemical charging as a function of time. The effects of charging duration and particularly the delay period between charging and mechanical tensile testing were investigated. Unsurprisingly, longer charging time shows a greater loss of elongation; however, a more extensive recovery of ductility correlated with longer charging time in the first few days after charging. The data also show that while the uncharged mild steel met all minimum required values for strength and elongation for the specified grade, there was a substantial variability in the elongation to failure. The same trends in variability of elongation translated to the hydrogen-charged specimens. Due to this extensive variability, failure to meet the elongation specification of the grade is reported based on the worst-case scenario obtained for a given set of samples for each exposure condition. These results have practical implications for the monitoring and testing of infrastructure exposed to hydrogen, particularly as this relates to industry planned operational shutdown schedules.

Application of Hydrogen Permeation Techniques to Assess the Effect of Inhibitors in Hydrochloric Steel Pickling of Low‐C Steels and Interstitial‐Free Steels

The acid pickling phase, generally entrusted to HCl‐based solutions, plays a fundamental role in the production of low‐C and interstitial‐free steel coils. Very often, however, pickling operations are challenging due to the possible onset of surface defects (underpickling, overpickling, appearance of surface defects, etc.) linked to complex phenomena involving numerous factors, such as acid concentration, Fe ions in solution, temperature, time, steel type, and scale structure. Moreover, the use of inhibitors, which is essential for controlling the pickling process, represents one of the major challenges. Their dosage, although minimal, must be carefully chosen based on the type of processed coils and other plant engineering variables. The flow of hydrogen that is generated on the surface of the steel during etching causes absorption of hydrogen by the metal and its measurement is strictly linked to the phenomena occurring during scale removal. The correlation of data obtained from a Devanathan double‐cell hydrogen permeation system to results of other techniques, such as weight loss, surface analysis, metallography, and electron microscopy shows that this system can be effectively used to indirectly measure the solution aggressiveness. This experimental approach is applied to two industrial steels: a simple carbon base and an interstitial free Ti steel.

Effect of Boron Content in LiOH Solutions on the Corrosion Behavior of Zr-Sn-Nb Alloy.

In pressurized water reactors, LiOH may be concentrated in some areas, leading to the accelerated corrosion of fuel claddings. Injecting boric acid into primary coolants can mitigate the accelerated corrosion effect of LiOH on Zircaloys, but the effects of boron content on the corrosion behavior of the Zr-Sn-Nb alloy are still unknown. This work focused on the corrosion and hydrogen absorption behavior at 360 °C/18.6 MPa in 100 mg/kg LiOH solutions with 0 mg/kg, 50 mg/kg, and 200 mg/kg boron contents for up to 510 days, aiming to study the effect of boron content on corrosion resistance in LiOH solutions. Corrosion kinetics, microstructures of oxide films, hydrogen absorption concentrations and hydride morphology were obtained after the test. The results show that injecting boron in LiOH solutions can significantly reduce the corrosion weight gain, hydrogen concentration, and hydrogen length of Zr-Sn-Nb alloys, that is, improving corrosion resistance effectively. During the oxidation of the Zr-Sn-Nb alloy, B3+ and Li+ incorporate in oxide films. The incorporation of Li+ may lead to the generation of oxygen vacancies, which can carry oxygen from the solutions to O/M interface, accelerating corrosion. The incorporation of B3+ in oxide films will slow down the oxidation of Zr-Sn-Nb alloys by reducing the oxygen vacancies caused by Li+ aggregation.

Advancements in the modification of magnesium-based hydrogen storage materials

Magnesium-based hydrogen storage materials represent a hydrogen storage technology with broad application prospects. As the global energy crisis and environmental pollution issues become increasingly severe, hydrogen, as a clean and efficient energy source, has garnered growing attention. Magnesium-based hydrogen storage, serving as a crucial means for storing and transporting hydrogen, is gaining prominence due to its abundant resources, low cost, low density, and high hydrogen storage density. However, challenges in terms of absorption/desorption rates, temperature, activation energy, and enthalpy during hydrogen application impede its development. To address these challenges, this paper systematically reviews current research on magnesium-based hydrogen storage materials, encompasses their types, characteristics, and hydrogen absorption mechanisms. Furthermore, it delves into the impacts of nanoscale dimensions, alloying, doping, and catalysis on the performance of magnesium-based materials. The aim is to provide valuable insights for research in related fields.

Hydrogen Absorption in Palladium‐Based Nanocrystals for Electrocatalysis Investigation

AbstractHydrogen absorption in transition metals has received enormous attention for applications such as the hydrogen storage, sensing and corrosion. In particular, the Pd‐H system is a simple and classical metal hydride system that serves as a platform for a deeper understanding of hydrogen behavior. In the past few years, Pd‐H has been reported as electrocatalyst in multiple reactions, whereas the impact of hydrogen absorption/desorption in electrocatalytic applications remains unclear. Therefore, in this concept, factors influencing the hydrogen adsorption/desorption of palladium in the gas phase, such as facet engineering, ligand effects, and alloying effects, are summarized. Subsequently, in the context of electrocatalysis, factors affecting electrochemical hydrogen adsorption/desorption are outlined. Particularly, prospects for the further investigation of electrochemical hydrogen adsorption/desorption in catalysis are discussed.

Time-Dependent Multi-Particle Model Describing the Hydrogen Absorption of Nanocrystalline Magnesium Powders: A Case Study

Classical kinetic models describing the hydrogen absorption of nanocrystalline metallic hydrides generally do not involve any parameter related to the change in the crystallite size during the hydrogenation at constant temperature. In the present investigation, ball-milled nanocrystalline Mg powders exhibiting lognormal crystallite size distribution have been subjected to hydrogen absorption in a Sievert-type apparatus. Partially absorbed states were achieved by interrupting the hydrogenation cycle at different hydrogen content, i.e., when 15%, 50%, and 90% of Mg powder transformed to MgH2. The evolution of the characteristic size of the nucleating MgH2 phase was determined from X-ray diffraction analysis. Considering the crystallite size distribution of the as-milled powder agglomerate as well as the growth during the isothermal hydrogenation process, a time-dependent multi-particle reaction function ∝CV¯t;R(t) was developed. It was shown unambiguously for this case study that the measured hydrogen absorption curve of the ball-milled Mg powder shows the best correlation with this model when it is compared to classical kinetic functions or the previously developed multi-particle reaction function excluding the change in the average crystallite size during hydrogenation.

Innovative Design of Solid-State Hydrogen Storage and Proton Exchange Membrane Fuel Cell Coupling System with Enhanced Cold Start Control Strategy

This paper presents an innovative thermally coupled system architecture with a parallel coolant-heated metal hydride tank (MHT) designed to satisfy the hydrogen supply requirements of proton exchange membrane fuel cell s(PEMFCs). This design solves a problem by revolutionising the cold start capability of PEMFCs at low temperatures. During the design process, LaNi5 was selected as the hydrogen storage material, with thermodynamic and kinetic properties matching the PEMFC operating conditions. Afterwards, the MHT and thermal management subsystem were customised to integrate with the 70 kW PEMFC system to ensure optimal performance. Given the limitations of conventional high-pressure gaseous hydrogen storage for cold starting, this paper provides insights into the challenges faced by the PEMFC-MH system and proposes an innovative cold start methodology that combines internal self-heating and externally assisted preheating techniques, aiming to optimise cold start time, energy consumption, and hydrogen utilisation. The results show that the PEMFC-MH system utilises the heat generated during hydrogen absorption by the MHT to preheat the PEMFC stack, and the cold start time is only 101 s, which is 59.3% shorter compared to that of the conventional method. Meanwhile, the cold start energy consumption is reduced by 62.4%, achieving a significant improvement in energy efficiency. In conclusion, this paper presents a PEMFC-MH system design that achieves significant progress in terms of time saving, energy consumption, and hydrogen utilisation.

STUDY OF HYDROGEN-HELIUM PERMEABILITY OF SILICATE MICROSPHERES AND SORBENT BASED ON THEM

The work is devoted to research on the applicability of the membrane-sorption method for the separation of hydrogen-helium mixtures. The sorption dependences of hydrogen and helium absorption were experimentally obtained for synthetic hollow microspheres made of sodium borosilicate glass of the MS-V-1L type, silica microspheres and granular sorbent based on MS-V-1L microspheres. A significant difference in the rates of sorption processes of hydrogen and helium for the sorbents under study was shown. Based on the gas diffusion model, the kinetic characteristics of absorption, permeability and selectivity coefficients, and dynamic characteristics of the processes of sorption of hydrogen and helium of heliumhydrogen mixtures of various compositions by these sorbents were determined. For silica microspheres, the selectivity coefficient with respect to hydrogen and helium at T = 24 C exceeds 130, and for a granular sorbent based on MS-V-1L microspheres it is about 1000 at T =110 C. The high selectivity values of the studied sorbents confirm the possibility and efficiency of using the membrane-sorption method for the separation of hydrogen-helium mixtures.

A novel carbon-induced-porosity mechanism for improved cycling stability of magnesium hydride

MgH2 has been extensively studied as one of the most ideal solid hydrogen storage materials. Nevertheless, rapid capacity decay and sluggish hydrogen storage kinetics hamper its practical application. Herein, a Ni/C nano-catalyst doped MgH2 (MgH2Ni/C) shows an improved hydrogen absorption kinetics with largely reduced activation energy. Particularly, the MgH2Ni/C displays remarkable cycling stability, which maintains a high capacity of 6.01 wt% (98.8 % of initial capacity) even after 50 full hydrogen ab/desorption cycles, while the undoped MgH2 counterpart retains only 85.2 % of its initial capacity. Detailed microstructure characterizations clearly reveal that particle sintering/growth accounts primarily for the deterioration of cycling performance of undoped MgH2. By comparison, MgH2Ni/C can maintain a stable particle size with a growing porous structure during long-term cycling, which effectively increases the specific surface of the particles. A novel carbon-induced-porosity stabilization mechanism is proposed, which can stabilize the proportion of rapid hydrogen absorption process, thus dominating the excellent cycling performance of MgH2Ni/C. This study provides new insights into the cycling stability mechanism of carbon-containing Mg-based hydrogen storage materials, thus promoting their practical applications.

Correlation between hydrogen absorption capacity and microstructure of Fe-rich Sm-Co-Fe-Cu-Zr permanent magnetic alloys

The correlation between hydrogen absorption capacity (HAC) and the microstructure of Sm26.2CobalFexCu4.0Zr2.3 (x = 23 wt%, 25 wt%, 27 wt%, 30 wt%) ingots and cast strips was systematically investigated. As the temperature rises from 373 to 423 K, the activation time, hydrogen absorption time and HAC of the Sm26.2CobalFe23Cu4.0Zr2.3 ingot decrease by 14.4%, 14.1%, and 19.3%, respectively. Dispersed 1:5 phase provides more channels for hydrogen diffusion, which is the main reason that HAC increases with the x increasing. The HAC of the same compound strips increases as the particles size of the pre-crushed decreases. However, no further embrittlement behavior appears in pre-crushed strips, which reaches an equal HAC as ingots. Micro-computerized tomography reveals that ingots contain small spherical-like holes and large flake micro-cracks, whereas strips mainly contain elliptical pores. The effects of grain size and inner defects size on structure stability were invested by Abaqus. Simulation results reveal that the superior embrittlement behavior of the ingots is predominantly influenced by the presence of large flake-like micro-cracks.

Effect of double substitution on hydrogen absorption-desorption properties of Ti2CrV alloy

Doubly substituted Ti2CrV alloy with composition Ti1.5Sc0.3CrVNi0.2 was prepared by arc melting method followed by annealing. The annealed alloy exists in body centred cubic (BCC) structure and shows fast kinetics for hydrogen absorption and desorption at room temperature. BCC phase of the alloy undergoes phase transformation to face centred cubic (FCC) hydride phase with H atoms occupying tetrahedral sites in the lattice, reaching an overall H/M ratio >2.2 (storage capacity ∼ 4 wt%). Storage capacity decreases by 40% in the 2nd cycle and then stabilizes at a value of ∼2.5 wt% for the subsequent 10 cycles. A drastic reduction in hydride desorption temperature upon double substitution (Sc and Ni substitution in Ti2CrV alloy) has been confirmed by DSC studies. Furthermore, the change in isotope effect in doubly substituted Ti2CrV alloy is discussed in light of thermal stabilities of the hydrides and deuterides.

Passive high explosive neutron inspection (PHENIX): a new method to confirm the presence or absence of high explosives for nuclear treaty verification

Advanced instruments and methods need to be developed now to create a technical basis to support the negotiation of future nuclear arms control treaties. One new capability that is anticipated is the ability to confirm either the declared presence or declared absence of high explosive (HE) material in the presence of special nuclear material (SNM). Towards this goal, Passive HE Neutron Inspection (PHENIX) has been developed and demonstrated as a method for confirming the presence or absence of HE in the presence of plutonium. The method exploits the inherent presence of neutrons associated with the decay of plutonium as an internal probe source for performing prompt gamma-ray neutron activation analysis (PGNAA), searching for the presence of HE as revealed by the emission of characteristic gamma rays following neutron absorption in hydrogen and nitrogen which are building blocks of present-day, military-grade HE. Tests using stoichiometrically-correct hemishells of mock HE with plutonium show that a system can be expected to positively confirm the presence or absence of these signatures, supporting determination of HE presence or absence with Pu, in a few hours. To protect other potentially sensitive gamma-ray signatures from a treaty accountable item, an analog information barrier has been conceptualized and tested which physically prevents the collection of gamma-ray spectral data outside of user selected energy windows strategically chosen to view only narrow spectral regions corresponding to the hydrogen (2223.2 keV) and nitrogen (9807.2 keV, 10,318.2 keV, and 10,829.2 keV) PGNAA signatures.

Hydrogen permeation resistance of ZrN thin film deposited by ion-plating

Hydrogen absorption of Zircaloy nuclear fuel cladding, used in light water reactor at nuclear power plants, poses an increased risk of delayed hydride cracking during interim dry storage. Consequently, novel surface technologies aimed at reducing hydrogen absorption have become a critical area of research. Zirconium nitride coatings, renowned for their high hardness, corrosion resistance, and wear resistance, have seen widespread application in various industries, including medical devices, cutting tools, and decoration. This study explores the effectiveness of ZrN coating in suppressing hydride formation in Zircaloy-4, a material commonly used for nuclear fuel cladding. In this research, ZrN coatings were deposited onto recrystallized Zircaloy-4 substrates using a hollow cathode discharge ion-plating (HCD-IP) system. The coated and uncoated Zircaloy-4 samples were then subjected to electrochemical and gaseous hydriding processes. The study further investigates the differences in microstructure and hydrogen content of coated and uncoated Zircaloy-4. From these results, it is evident that the ZrN thin film deposited by HCD-IP exhibited great resistance to hydrogen permeation against both hydriding conditions. It is concluded that the ZrN thin films can serve as an excellent hydrogen barrier layer for Zircaloy-4.

Peculiarity of hydrogen absorption in duplex steels: Phase-selective lattice swelling and stress evolution

Electrochemical hydrogen absorption in duplex steels is not fully understood. In this work, an in-situ synchrotron cross-sectional X-ray micro-diffraction analysis is performed on steel with comparable phase fractions of ferrite and austenite, coupled with electrolytic hydrogen charging. The results reveal that charging with a constant current density of 10 mA/cm² for 5 h leads to expanding the austenitic lattice to a depth of approximately 250 µm, up to ≥0.15 %. In contrast, the lattice parameter of the ferrite phase remains unchanged during this process. As the austenite expansion progresses, it generates different amounts of equivalent in-plane compressive stresses, which amount to approximately -150 and -450MPa in the austenite and ferrite phases at the sample surface, respectively. Using a finite element model of grain interaction, this difference is qualitatively interpreted by mutual mechanical constraints between ferrite and austenite, as well as between the hydrogen-charged surface layer and the underlying material.

Microstructure and fracture toughness of 850°C quenched and aged Zr-2.5Nb alloy

The Zr-2.5Nb alloy pressure tubes manufactured by Water Quenched and Aged (WQA) fabrication route has reportedly exhibited superior resistance against in-reactor dimensional changes. WQA route comprises three consecutive thermo-mechanical treatments viz., solution heat treatment (SHT), cold working and vacuum aging, which govern the final microstructure and therefore fracture toughness of the pressure tube material. This work describes the influence of SHT soaking duration, degree of cold working and aging temperature on the microstructure and fracture toughness of WQA Zr-2.5Nb alloy. WQA pressure tubes are expected to have better resistance to in-reactor dimensional changes. However, if proper care of hydrogen absorption during thermo-mechanical processing is not taken, though resistance to creep will improve expectedly but fracture toughness at ambient temperature will deteriorate.

Hydrogen trapping and embrittlement of titanium- and vanadium carbide-containing steels after high-temperature hydrogen charging

This work studies the effect of TiC and VC precipitate sizes on hydrogen trapping and embrittlement. Two experimental ferritic HSLA steels containing either TiC or VC carbides for precipitation strengthening are annealed in nitrogen and hydrogen gas. This results in a hydrogen uptake of up to 0.91 and 0.44 wppm in the TiC and VC steels, respectively. TEM and TDS analysis indicate that semi-coherent TiC particles trap hydrogen in misfit dislocations with an activation energy of 43 kJ/mol. Coherent VC particles are suggested to trap hydrogen in interface carbon vacancies, with an energy between 53 and 72 kJ/mol. Carbon vacancies are the likely trapping site in incoherent precipitates, where SIMS imaging confirms that incoherent TiC precipitates trap preferentially near the interface, whereas incoherent VC precipitates trap throughout their bulk. Neither alloy is embrittled in SSRT tests after hydrogen absorption, which shows that these precipitates can be used as both a hydrogen sink and a strengthening mechanism in steels.Graphical abstract

The study of La and Mg elements on the improved structure and hydrogen storage performance of Ca2MgNi9 alloy

In order to improve the comprehensive hydrogen storage performance of AB3-type (RE/Ca)-Mg-Ni alloys, a new series of Ca(Ca0.75La0.25)2-xMgxNi9 (x = 0.8, 0.9, 1.0, 1.1, 1.2) alloys is designed and prepared. Based on the as-cast Ca2MgNi9 alloy, La is introduced, and the ratio of rare earth (RE) to Mg is adjusted using the induction melting method. This alteration modifies the microstructure of the alloy and significantly enhances its hydrogen storage performance. The effects of microstructure on hydrogen storage performance and mechanism are analyzed. The phase composition and lattice parameters of the main phase are regularly regulated by appropriate element substitution. The lattice parameter of the main phase is increased, the capacity and kinetics of hydrogen storage are significantly improved. The initial hydrogen absorption capacity of the alloy increases from 1.744 wt% for Ca2MgNi9 to 1.975 wt% for Ca(Ca0.75La0.25)1.2Mg0.8Ni9 alloy. Furthermore, the synergistic regulation of La and Mg elements can increase the hydrogen desorption ratio and crystal structure stability of the alloy. This leads to the concurrent enhancement of effective hydrogen storage and cycle performance of the Ca2MgNi9 hydrogen storage alloy. The retention rate of hydrogen absorption capacity for the 50th cycle is increased from 77.13% for Ca2MgNi9 to 84.26% for Ca(Ca0.75La0.25)0.8Mg1.2Ni9. At the same time, owing to the adjustment of the cell volume and phase composition, the platform pressures of hydrogen absorption and desorption of the alloy have also experienced a multi-fold increase between 0.002 and 0.5 MPa at 303 K. This enhancement is advantageous for expanding the potential applications of this type of alloy. This work presents new ideas for enhancing the hydrogen storage performance of Ca2MgNi9 hydrogen storage alloys.

Magnetic property changes of NdGa upon hydrogen absorption

Rare earth monogallide (REGa) Zintl phases are attractive for their properties in hydrogen storage and magnetic cooling. However, the magnetic effects upon hydrogen additions in REGa are not well understood. This study aims to explore the magnetic effects in REGaHx using SQUID magnetometry and neutron powder diffraction. To avoid challenges due to absorption and high incoherent scattering in the neutron diffraction experiments, the compound NdGaDx (x = 0, 0.9, or 1.6) was chosen for examination. It was found that NdGa exhibits two ferromagnetic structures below the Curie temperature of 42 K. Just below 42 K the magnetic moments are oriented along the crystallographic c axis, and at 20 K a spin reorientation occurs where the moments turn ∼30∘ toward the a axis. Upon partial deuteration (x = 0.9), the magnetization decreases and two magnetic phases are observed, one intermediate incommensurate phase, and one canted ferromagnetic phase with the net magnetization aligning along the b axis. For the full deuteride (x = 1.6) only one incommensurate magnetic phase is observed at low temperatures. Magnetometry also reveals that there are no isotope effects when absorbing H or D. The absorption of H or D changes the Nd-Nd distances as well as the electronic structure, which results in a drastic change in the magnetic properties as compared to NdGa. Published by the American Physical Society 2024

A Phenomenological Model for Interstitial Hydrogen Absorption in Niobium

A Phenomenological Model for Interstitial Hydrogen Absorption in Niobium