Hydrogen Absorption Behavior Research Articles

Oxidation and compositional modulation in single phase C14 Zr0.6Ti0.4Fe1Cr1 alloy

This study investigates the effects of heat treatment on the crystal structure and hydrogen absorption behavior of the AB2 type metal hydride Zr0.6Ti0.4Fe1Cr1. The objective is to understand how 3- and 6-day heat treatments at 1000°C influence the alloy's microstructure and hydrogenation properties. Using electron microscopy, EBSD analysis, X-ray diffraction, and hydrogenation measurements, we found that the as-cast alloy exhibits rapid hydrogen absorption with significant compositional variations due to segregation during casting, confirmed by a single C14 Laves phase in XRD. Heat treatment slowed hydrogen absorption and reduced hydrogen capacity, with XRD indicating the structure remained primarily C14 Laves phase. However, SEM/EDS analysis showed substantial microstructural changes, including the emergence of new phases and segregation of Zr-rich phases, likely non-hydride forming, influenced by elevated oxygen content. These new phases probably contribute to the reduced hydrogen uptake capacity.

Influence of Lubricated Rolling/Sliding Tribotesting on Hydrogen Trapping in 100Cr6 Bearing Steel

As hydrogen reduces the fatigue life of 100Cr6 bearing steel significantly, extensive research on the interaction of hydrogen with 100Cr6 is necessary. This study investigated the influence of rolling/sliding tribotesting performed on a micro-pitting-rig on the hydrogen absorption and trapping behaviour of 100Cr6 bearing steel. Thermal desorption mass spectrometry was used to compare the hydrogen desorption spectra of 100Cr6 samples after tribological tests and static heated oil-immersion tests to untested reference samples. The approach was chosen to further understand the influence of both microstructural deformation as well as steel-oil contact on the hydrogen absorption and trapping behaviour of 100Cr6. The tribological test showed a stable friction behaviour and mild wear which was dominated by local plastic deformation of surface asperities. Despite the mild wear, a change in de-trapping temperatures was found for tribotested samples compared to oil-immersed and untested reference samples. This finding indicates that even mild tribotesting conditions alter the hydrogen trapping behaviour of 100Cr6 bearing steel.

Investigation on nanoindentation and TOF-SIMS applications in the hydrogen and oxygen absorption behavior of Zr-Sn-Nb alloys

This paper focuses on nanoindentation and TOF-SIMS (time-of-flight secondary ion mass spectrometry) small-scale test methods in the study of hydrogen absorption and oxygenation behavior analysis of Zr-Sn-Nb oxidized at 650°C −1200 °C. The CSM (Continuous Stiffness Method) test demonstrates the hardness fluctuations caused by element proliferation in post-high temperature oxidation microstructures. The deformation resistance ability of typical microstructures is as follows: β-Zr layer > α-Zr(O) layer > ZrO2 layer. In addition, hydrogen-induced softening occurred in steam-containing hydrogen conditions (HIT=2～3Gpa), compared to steam (HIT=5～16Gpa). The 1200℃ load-displacement curve demonstrates that the pop-in (or pop-out) effect exists in the Zr-Sn-Nb alloy, related to the influence of hydrogen charge, essentially to dislocation nucleation, winding, and movement. TOF-SIMS provides an effective method for small molecular chemical elements, such as H and O, while ZrO, ZrO2, ZrO2H, ZrO3H, OH, and O2 ions also be found. Based on these results, this study also hypothesizes the OH- dominated oxidation reaction equation.

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.

Microstructural study on the slope of plateau pressure in TiFe0.8Al0.2 hydrogen storage alloy

In the TiFe0.8Al0.2 alloy, the Ti2Fe phase was precipitated, and the B2 phase was separated into two B2 phases. The alloy absorbed hydrogen at room temperature without any thermal activation process by forming the Ti2Fe phase. The hydrogen absorption and desorption behaviors were examined, and the slope of the plateau pressure was severely formed. The two B2 phases had different compositions. The hydride-forming enthalpies of the two B2 phases were calculated through a density function theory calculation, and the values of the two B2 phases were different. Therefore, it was confirmed that the slope of the plateau pressure was severely formed because of the separation of the B2 phase.

Effects of chemisorption impurities on hydrogen diffusion mechanism from Pd(100) surface into subsurface

The impurities exhibit a remarkable impact on adsorption, absorption, and diffusion behavior of hydrogen on catalyst surface, and prompt an essential ongoing challenge on security and development strategy in hydrogen production, separation, purification, and utilization. Given this, S and CO impurities accompanied with or without atomic hydrogen, i.e. S, S + H, CO, and CO + H, were focused to discreetly elucidate their influences on microscopic mechanism for hydrogen travelling into Pd(100) subsurface in terms of spatial orientations and distinct coverages. All viable minimum energy pathways were thoroughly explored by climbing image nudged elastic band method, in which substrate relaxation and reconstruction effects were considered. Quantum results manifest that S or CO overwhelmingly changes structural and electrical properties of metal surface, and thus facilitates hydrogen diffusion, except for ones on H3 site at 0.25 ML coverage. Whereas, H in both S + H and CO + H shows inhibition effect by increasing barrier and blocking active surface site.

Formation of Plasma-Nitrided Barrier Layers Against Hydrogen Absorption and Diffusion in Pure Iron

Hydrogen embrittlement is a serious problem for steels such as high strength steels. Reducing hydrogen absorption into steels is required for the prevention of hydrogen embrittlement. In order to improve the hydrogen absorption resistance into steels, a nitriding treatment is one of the effective ways among surface modifications because nitriding may increase the overpotential for the hydrogen evolution reaction on the surface and decrease hydrogen diffusivity in nitrided layers. In this study, the phase structure in the nitrogen compound layers for the pure iron specimens was controlled by plasma nitriding with different types of plasma gas and gas composition. The influence of ε-Fe2-3N and γ’-Fe4N phases on hydrogen absorption into the inside of the pure iron matrix through the nitrided layers was evaluated. During the hydrogen permeation tests, the plasma-nitrided specimens showed small permeation current values compared to the as-polished specimen when it reached the steady state. Especially, hydrogen absorption and permeation for the specimen with the compound layer containing ε-Fe2-3N were extremely inhibited. Hydrogen absorption and permeation behaviors in the nitrided pure iron specimens were discussed in terms of the catalytic activity and hydrogen diffusivity.

The effects of hydrogen absorption in U3Si5 and its thermodynamic properties

The hydrogen absorption behavior of ▪ was examined using a Sieverts apparatus. Experimental results revealed the formation of a hydride phase with a stoichiometry reaching ▪ at pressures up to 250 kPa and temperatures below 300°C. By employing Van 't Hoff analysis, the enthalpy and entropy of formation for the newly formed hydride phase were measured as -19.73 kJ⋅mol−1 and -251.18 J⋅mol−1⋅T−1, respectively. Rietveld refinement showcased an expansion in lattice parameters a and c, resulting in an overall increase in unit cell volume of up to 8%; volume expansion can induce structural failures within the material.

Study on the microstructure and hydrogen storage property changes of cast TiFe0.9Cr0.1 alloy by homogenization annealing

This study investigated the changes in the microstructure and hydrogen storage properties of cast TiFe0.9Cr0.1 alloys by homogenization annealing. The as-cast and homogenized samples consisted of B2 and C14 Laves phase. After annealing, compositions of the B2 phase in both samples were similar, while the Laves phase fraction decreased and the Cr concentration in the Laves phase increased. To understand the microstructure changes caused by annealing, the fraction and the composition of the phases in the equilibrium state were derived using thermodynamic calculation, where the microstructure of the as-cast sample changed to the direction in the equilibrium state by annealing. The first hydrogenation kinetics were examined in the as-cast and homogenized samples, which slowed in the latter as the Laves phase fraction decreased. The hydrogen absorption and desorption behaviors were compared using a pressure-composition-temperature diagram at 50 °C. Since the compositions of the B2 phase in the two samples were almost the same, the two samples represented similar hydrogen storage behaviors. From the first-principles density functional theory calculation, the hydride-forming enthalpy of the B2 phase was calculated. By using an equation to predict the desorption plateau pressure from the hydride-forming enthalpy, the desorption pressure was predicted to be 1.34 bar, a value similar to the desorption pressure obtained from the experiment.

Study of the hydrogen absorption behaviour of a “number-sensitive” Mg atom: ultra-high hydrogen storage in MgHn (n = 1–20) clusters

A DFT study of MgHn (n = 1–20) clusters shows that a single Mg atom exhibits a magical ability of "odd–even recognition" of the attraction of H atoms, and MgH7 and MgH12 clusters have an impressive storage capacity of 22.69 wt% and 33.47 wt%.

AC interference on hydrogen absorption in low carbon steel under cathodic protection

The effect of AC and cathodic protection (CP) potentials on hydrogen evolution and absorption in carbon steel 1010 is investigated by hydrogen permeation tests, using a Devanathan-Stachurski electrochemical cell. Hydrogen evolution reaction occurs via the coupled discharge-recombination mechanism under CP and AC. Hydrogen permeation is controlled by bulk diffusion and less than 1% of the total hydrogen permeates through the steel membrane. A significant increase in the hydrogen uptake occurs as the AC voltage increases with more negative CP potentials. More negative CP potentials increase the hydrogen flux and absorption under AC imposition. The highest effective hydrogen diffusivity (∼5 × 10−8 cm2/s) and subsurface hydrogen concentration (∼3.5 × 10−5 mol/cm3) are found at −1.5 VSCE with AC imposition. These results demonstrate a synergy between the CP potential and AC voltage on the hydrogen evolution and absorption behavior in steel and provide insights into the implications of AC interference with CP on hydrogen embrittlement.

Probing hydrogen properties at conditions found inside red dwarf stars

Modified fusion experiment provides an ideal testbed for uncovering hydrogen absorption behavior at extreme densities

Corrosion-induced hydrogen evolution, absorption, and cracking behaviors of ultra-high-strength galvanized and galvannealed steel sheets

Various experimental analyses on hydrogen evolution, absorption, and cracking behaviors were conducted to gain a fundamental understanding of the hydrogen embrittlement of ultrastrong steel sheets with galvanized (GI) and galvannealed (GA) coatings. The hydrogen evolution and absorption behaviors are controlled primarily by the potential differences between the coating and exposed steel substrate, and the corrosion-induced damage pattern of the coating. The higher absorption rate of hydrogen was more pronounced in corroded GI-coated steel caused by the larger cathodic polarization applied to the exposed substrate, and a more severe form of coating dissolution by aqueous corrosion in a 3.5% NaCl + 0.3% NH4SN solution. In contrast, the corrosive species can only penetrate through the pre-existing cracks in the brittle Fe-Zn intermetallic phases composed of the GA coating, and the driving force for hydrogen evolution becomes smaller. These result in significant differences in hydrogen penetration and cracking behaviors between the two coated ultrastrong steels.

Hydrogen absorption due to wear between Ni–Ti superelastic alloys in water

Hydrogen absorption behavior has been investigated during wear between Ni–Ti superelastic alloys in purified water at room temperature by a hydrogen thermal desorption analysis. For the present wear test under a rotation speed of 100 rpm and an applied load of 2.0 N, the amounts of mass and thickness losses of a specimen increase without marked corrosion with increasing wear time. Even after 0.5 h, there is sufficient hydrogen absorption (approximately 12 mass ppm) to be detected. The amount of desorbed hydrogen (absorbed hydrogen) increases with increasing wear time. The hydrogen desorption behavior of wear specimens is not necessarily the same as those of cathodically hydrogen-charged specimens and specimens that absorbed hydrogen in acid solutions, as reported previously. The residual martensite phase and hydride are observed after the wear test. The present results indicate that Ni–Ti superelastic alloy absorbs a substantial amount of hydrogen, which causes hydrogen embrittlement, during wear in water within a short time.

Hydrogen absorption and diffusion behaviors in cube-shaped palladium nanoparticles revealed by ambient-pressure X-ray photoelectron spectroscopy

The hydrogen absorption and diffusion processes in cube-shaped palladium (Pd) nanoparticles (NPs) were studied by the combination of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and density functional theory (DFT) calculations. A size dependence of the subsurface hydrogen absorption was observed. More hydrogen atoms were absorbed in the subsurface of the smaller-sized Pd NPs owing to the enhancement of the diffusivity of H atoms from the surface into the subsurface rather than the adsorption or absorption rates at the initial stages. This results from the weakened Pd-H bond caused by surface disordering of Pd NPs with the reduction of the size of the particles. Furthermore, we discuss the H absorption sites in the bulk by comparing the relative Pd 3d core-level binding energy shifts of the Pd atoms obtained from the AP-XPS results and the theoretical calculations. The octahedral (O) sites are shown to be more favorable than the tetrahedral (T) sites for hydrogen occupation by comparing the experimental results and theoretical calculations. Finally, we proposed an interaction model between hydrogen and the Pd NPs during H2 absorption and diffusion to provide new insights into the hydrogen absorption process.

Effect of hypo-stoichiometry on microstructure and hydrogenation behaviors of multiphase ZrTi0.1V2-x alloys

ZrTi0.1V2-x (x = 0, 0.2, 0.4) alloys are designed to investigate the effect of hypo-stoichiometry on hydrogenation properties of Laves phase dominated multiphase alloys. The samples are synthetized by arc melting and homogenizing annealing treatment. Phase abundances and lattice parameters are studied by XRD and Rietveld refinement. The morphology of each phase is confirmed by SEM and EDS, hydrogenation kinetics, pressure-composition-temperature characteristics and hydrides have been studied. Annealing increases the content of Laves phase and Zr3V3O, while decreases that of V-BCC and α-Zr. The decrease in atomic ratio B/A, i.e. V/(Zr + Ti), results in the increase of Zr3V3O, the decrease of Laves and V-BCC, and the lattice expansion for each phase. Alloys show easy activation and fast hydrogenation kinetics, which is controlled by a different process. Hydrogen absorption capacity and formation enthalpy increase while equilibrium pressure decreases with the decrease in B/A ratio, which could be related to the decrease of V-BCC phase and lattice expansion for each phase. Zr8V16H36.29 is the dominated hydride after saturated hydrogenation, the proportion of hydrides and their hydrogen mass fraction accord with the hydrogen absorption behavior. Among the samples, ZrTi0.1V1.6 shows the best overall properties for rapid and massive hydrogen absorption at low pressure.

Hydrogen absorption/desorption reactions of the (TiVNb)85Cr15 multicomponent alloy

Ti-V-Nb-Cr alloys have been reported as potential candidates for hydrogen storage applications. Investigating the processes of absorption and desorption is paramount to understand the hydrogen storage properties of these novel alloys and to develop more efficient hydrogen storage materials. In this work, we investigated the hydrogen absorption/desorption reactions of the (TiVNb)85Cr15 BCC multicomponent alloy by laboratory and synchrotron X-ray diffraction, Pair Distribution Function (PDF) analyses, Transmission Electron Microscopy (TEM) and thermo-desorption analyses (TDS). Hydrogen absorption behavior was studied by pressure-composition-isotherm (PCI) at room temperature, which demonstrated levels of absorption around 2 H/M (H/M = hydrogen-to-metal ratio) with low equilibrium pressure. The results showed a multi-step hydrogenation process: alloy ↔ BCC solid solution ↔ BCC intermediate hydride ↔ FCC dihydride. PDF analyses showed that the partially hydrogenated alloy at different levels of H/M and the fully hydrogenated alloy can be reasonably described by models with phases presenting random atomic distribution in the metal crystallographic sites. Moreover, the partially hydrogenated sample prior to the complete formation of the intermediate hydride showed evidence of two co-existing BCC phases.

Hydrogen Absorption and Desorption Behavior on Aluminum-Coated Hot-Stamped Boron Steel during Hot Press Forming and Automotive Manufacturing Processes.

Our study mainly focused on diffusible hydrogen in aluminum–silicon-coated hot-stamped boron steel during a hot press forming process and in pre-treatment sequential lines of the automotive manufacturing process using a thermal desorption spectroscopy (TDS) technique. First, in the hot stamping procedure, as the soaking time increased in the heating furnace at a specific dew point when austenitizing, a high concentration of diffusible hydrogen was absorbed into the hot-stamped boron steel. Based on the TDS analysis of hydrogen absorbed from hot stamping, the activation energy value of hydrogen trapping in 1.8 GPa grade steel is lower than that of 1.5 GPa grade steel. This means that diffusible hydrogen can be more easily diffused into defective sites of the microstructure at a higher level of the tensile strength grade. Second, in sequential pre-treatment lines of the automotive manufacturing process, additional hydrogen did not flow into the surface, and an electro-deposition process, including a baking procedure, was effective in removing diffusible hydrogen, which was similar to the residual hydrogen of the as-received state (i.e., initial cold rolled blank). Based on these results, the hydrogen absorption was facilitated during hot press forming, but the hydrogen was sequentially desorbed during automotive sequential lines on aluminum-coated hot-stamped steel parts.

First-principles study of hydrogen adsorption behavior in C15 Laves phase compound ZrV2

The hydrogen absorption behavior of C15 Laves phase compounds ZrV2 has been systematically investigated by the first-principles calculations. In the C15 Laves phase, hydrogen atoms can occupy three possible tetrahedral interstitial positions—2A2B, 1A3B, and 4B—in which the 2A2B site, being the largest interstitial space among the three possible positions, is the most favorable interstitial site. In addition, 2A2B and 1A3B sites can form some ordered clathrate-type structures to provide diffusion paths for hydrogen atoms to move inside the ZrV2 compounds. According to the calculated barrier energies of H atoms in different diffusion paths in ZrV2, it is found that hydrogen atoms prefer intra-ring diffusion to inter-ring diffusion, although inter-ring diffusion provides a non-negligible contribution to the overall H diffusion process. However, the existence of 1A3B sites can facilitate the diffusion of hydrogen atoms in adjacent six-membered rings. Finally, the absorption energies and electronic structures of ZrV2Hx (x = 0.5, 1, 2, 3, 4, 6, 7, and 12) were computed, and the results show that the hydrogen content reaches its maximum on the condition of 6 < x < 7. Moreover, hydrogen atoms make a stronger covalent bond with V atoms than with Zr atoms.

Exploring the hydrogen absorption and strengthening behavior in nanocrystalline face-centered cubic high-entropy alloys

The effect of marked change in grain size from coarse-grained to nanocrystalline can affect the hydrogen absorption and plastic deformation behavior in two face-centered cubic high-entropy alloys (HEAs), viz. equiatomic CoCrFeNi and CoCrFeMnNi. Thermal desorption analysis of the hydrogen-charged samples proved that grain boundaries act as hydrogen traps and thus largely increase the hydrogen contents in the nanocrystalline samples. A direct comparison in the hydrogen absorption between two HEAs confirms that both chemical composition and grain size are crucial factors contributing to the hydrogen solubility of the HEAs. The parameters for the thermally activated deformation from nanoindentation rate-jump tests suggest enhanced lattice friction by hydrogen, leading to a reduction in activation volume and thus modification of the plastic deformation processes. The results are discussed in two aspects, viz. the effect of grain size and chemical composition on the hydrogen-affected plastic deformation.