Internal Hydrogen Research Articles

Influence of internal hydrogen content on the evolved microstructure beneath fatigue striations in 316L austenitic stainless steel

The effect of internal hydrogen (up to 104.2 mass ppm) on the tensile and fatigue properties of SUS316L austenitic stainless steel was investigated. Internal hydrogen had minimal impact on the tensile properties but reduced the fatigue lifetime, but not monotonically with hydrogen concentration. The evolved microstructural state beneath the fatigue fracture surface showed commonalities and differences with crack length and the presence of hydrogen. Hydrogen influenced the evolved microstructural state, resulting in the formation of smaller dislocation cells with thicker cell walls, and modified the distribution of deformation twins. The non-linear dependence of the response on fatigue lifetime with increasing hydrogen concentration was attributed to hydrogen-induced changes in the macroscopic mechanical properties at the highest concentration. As the emphasis of this paper is on relating the hydrogen-induced changes in the deformed microstructural state to those in the mechanical properties, the results are discussed in terms of the hydrogen-enhanced localized plasticity mechanism.

Focal Point Evaluation of Energies for Tautomers and Isomers for 3-Hydroxy-2-Butenamide: Evaluation of Competing Internal Hydrogen Bonds of Types -OH…O=, -OH…N, -NH…O=, and CH…X (X=O and N).

The title compound is a small molecule with many structural variations; it can illustrate a variety of internal hydrogen bonds, among other noncovalent interactions. Here we examine structures displaying hydrogen bonding between carbonyl oxygen and hydroxyl H; between carbonyl oxygen and amino H; hydroxyl H and amino N; hydroxyl O and amino H. We also consider H-bonding in its tautomer 2-oxopropanamide. By extrapolation algorithms applied to Hartree-Fock and correlation energies as estimated in HF, MP2, and CCSD calculations using the cc-pVNZ correlation-consistent basis sets (N = 2, 3, and 4) we obtain reliable relative energies of the isomeric forms. Assuming that such energy differences may be attributed to the presence of the various types of hydrogen bonding, we attempt to infer relative strengths of types of H-bonding. The Atoms in Molecules theory of Bader and the Local Vibrational Modes analysis of Cremer and Kraka are applied to this task. Hydrogen bonds are ranked by relative strength as measured by local stretching force constants, with the stronger =O…HO- > NH…O= > -OH…N well separated from a cluster > NH…O= ≈ >NH…OH ≈ CH…O= of comparable and intermediate strength. Weaker but still significant interactions are of type CH…N which is stronger than CH…OH.

Effect of brush plating process variables on the microstructures of Cd and ZnNi coatings and hydrogen embrittlement

Brush plated ZnNi coating is evaluated for replacement of Cd coating during repair of sacrificial coatings on high strength steel components. Plating parameters such as deposition voltage, surface preparation and type of anode for coating deposition are used to study the risk of Internal Hydrogen Embrittlement (IHE). Coating characterization using Transmission Electron Microscopy (TEM) is correlated with Incremental Step Load (ISL) testing, permeation measurements and Thermal Desorption Spectroscopy (TDS) to evaluate the effect of microstructure and crystallographic defects within the coating on the risk of internal hydrogen embrittlement (IHE) of the substrate steel. It is observed that the coating microstructure plays an important role in mitigating IHE. Brush plated ZnNi coatings at 6 V deposition voltage with grit blast method of surface preparation and graphite anode, or deposition at 12 V with scotch-brite™ method of surface preparation and either of platinized Ti or graphite anode can suitably replace Cd coating. Presence of twin boundaries within the coating proved to be beneficial to decrease the risk of IHE by minimizing the H diffusion to the substrate. On the other hand, stacking faults and dislocations within the ZnNi coating do not sufficiently trap hydrogen and therefore do not mitigate the IHE risk when plated at 10 V and 12 V. Coating deposited at 6 V generates low amount of hydrogen, and does not cause IHE irrespective of the microstructure. TDS measurements performed to quantify the hydrogen desorption from different plating conditions indicate a direct correlation between the amount of hydrogen generated during plating and degradation of mechanical strength by IHE cannot always be established, principally because of the influence of microstructure.

Possibility of Doping CuGaSe2 n -Type by Hydrogen

Copper-indium-gallium-selenide (CIGS) alloys are successfully applied in thin-film solar cells. For a better use of the solar spectrum, they also offer the possibility of multijunction devices by tuning the composition in the different layers. As-grown CIGS is intrinsically p-type due to copper vacancies (${V}_{\mathrm{Cu}}$), but n-type doping is also useful for applications. While ${\mathrm{Cu}\mathrm{In}\mathrm{Se}}_{2}$ can be easily turned n-type, ${\mathrm{Cu}\mathrm{Ga}\mathrm{Se}}_{2}$ cannot, and this represents a problem, because increasing the band gap of CIGS requires a high $\mathrm{Ga}/\mathrm{In}$ ratio. Investigating the effect of hydrogen on ${\mathrm{Cu}\mathrm{Ga}\mathrm{Se}}_{2}$ by an optimized hybrid functional, we show that hydrogenation from an atomic source as, e.g., by a hydrogen plasma treatment, can turn the material n-type due to the formation of shallow donor ${V}_{\mathrm{Cu}}+2\mathrm{H}$ complexes, while ${\mathrm{H}}_{2}$ implantation, producing an internal hydrogen reservoir, can be used to produce semi-insulating material. We also show that under normal process conditions, unintentional hydrogen incorporation does not have a significant effect on ${\mathrm{Cu}\mathrm{Ga}\mathrm{Se}}_{2}$.

Hydrogen bonding effect on the thermal behavior of acidic ionic liquids

A relationship between the thermal performance (melting and thermal decomposition) and the internal hydrogen bonds for the protic ionic liquids pyridinium nitrate ([H–Pyr]+[NO3]–), pyridinium hydrogen sulfate ([H–Pyr]+[HSO4]–), pyridinium dihydrogen phosphate ([H–Pyr]+[H2PO4]–) and 4-amino-1H-1,2,4-triazolium nitrate ([4-AT]+[NO3]–) is investigated in the current work. For that purpose, melting/decomposition points, non-covalent bonding and intermolecular interaction are studied by means of TGA/DSC, reduced density gradient method and a Hirshfeld surface analysis.Results established that strong hydrogen bonds, rather than van der Waals interactions, influence the thermal behavior of the aforementioned ionic liquids in a great extent. Melting points of the compounds under investigation are found to decrease in order [H–Pyr]+[NO3]– > [4-AT]+[NO3]– > [H–Pyr]+[H2PO4]– > [H–Pyr]+[HSO4]– due a various hydrogen bonding degree. Overall decomposition of the pyridinium-based ionic liquids includes simple pyridine evaporation and protic acid (HNO3, H2SO4 and H3PO4) decay. However, decomposition of 2-aminotriazolium fragment (except HNO3) is also detected during [4-AT]+[NO3]– decay upon heating.

Protein-induced conformational change in glycans decreases the resolution of glycoproteins in hydrophilic interaction liquid chromatography.

An understanding of why hydrophilic interaction liquid chromatography gives a higher resolution for glycans than for glycoproteins would facilitate column improvements. Separations of the glycoforms of ribonuclease B compared to its released glycans were studied using a commercial hydrophilic interaction liquid chromatography column. The findings were used to devise a new hydrophilic interaction liquid chromatography column. For the commercial column, chromatograms and van Deemter plots showed that selectivity and efficiency are comparable factors in the higher resolution of the released glycans. The higher selectivity for the released glycans was associated with more water molecules displaced per added mannose. To investigate why, three-dimensional structures of the glycoprotein and the glycan were computed under chromatographic conditions. These showed that hydrogen bonding within the free glycan makes its topology more planar, which would increase contact with the bonded phase. The protein sterically blocks the hydrogen bonding. The more globular-shaped glycan of the glycoprotein suggests that a thicker bonded phase might improve selectivity. This was tested by making a column with a copolymer bonded phase. The results confirmed that selectivity is increased. The findings are possibly broadly relevant to glycoprotein analysis since the structural motif involved in internal hydrogen bonding is common to N-linked glycans of human glycoproteins.

Hydrogen-enhanced compatibility constraint for intergranular failure in FCC FeNiCoCrMn high-entropy alloy

The fundamental mechanism of hydrogen embrittlement was investigated in the high-entropy alloy FeNiCoCrMn using slow strain rate tensile tests with and without internal hydrogen. Hydrogen induced intergranular failure and reduced the average grain elongation parallel to the tensile axis, but also increased the local plasticity within grains. The influence of hydrogen on plasticity establishes a compatibility constraint across grain boundaries, which results in failure along the hydrogen-weakened grain boundaries. This study is the first to directly confirm the presence of the hydrogen-enhanced compatibility constraint in a high-entropy alloy and highlights the importance of developing a physical understanding of grain-scale interactions.

Study on the effect of protein buffer solution on hydrogen bonding of water molecules based on terahertz metamaterial absorber

The terahertz absorption of water is mainly caused by internal hydrogen bonds, and many proteins can maintain their biological activity only in liquid environment. This paper mainly studies the effect of active protein buffer solution on water-hydrogen bond to minimize the effect of water in buffer solution on terahertz. In order to improve the accuracy of the experimental results, a metamaterial absorber was designed to study its terahertz absorption characteristics by injecting protein buffer solution into the metamaterial-absorber. The effects of anions and cations of different protein buffer solutions on hydrogen bonds in water molecules were analyzed. The results show that the effect on the hydrogen bond of water molecules is mainly affected by the viscosity coefficient. The hydrogen bond association of water molecules can be broken when the viscosity coefficient is less than 0, and can be promoted when the viscosity coefficient is greater than 0. Therefore, the protein buffer solution can be composed of anions and cations whose viscosity coefficients are all less than 0.

Photo-anode surface modification using novel graphene oxide integrated with methylammonium lead iodide in organic-inorganic perovskite solar cells

The novel graphene oxide sheet-methylammonium lead iodide (GO-MAPbI3) was used as photoanode surface modification and is used as a photosensitizer for perovskite solar cells. The multi-crystalline presence of GO-MAPbI3-prepared photo-anode surface and surface morphologies were observed by high-resolution electron transmission microscopy and electron scanning microscopy. The selected electron diffraction pattern of GO-MAPbI3 has also been observed in a multi-crystalline nature. GO-MAPbI3 containing the elementary composition was determined using X-ray photoelectron spectroscopy. They consist of Pb 4f5/2 and Pb 4f7/2 and have an energy binding value of 143.9 (eV) and 138.9 (eV). GO-MAPbI3 was a crystalline cubic black color confirmed by an X-ray diffraction pattern. From the Fourier transform infrared spectra, graphene oxide functional groups, methylammonium lead iodide internal hydrogen bonding between the C–N group attached to the C–H group and its corresponding values. The photo-current density-voltage curves are regulated by GO-MAPbI3 coated on a photo-anode giving 8.39% of the power conversion efficiency.

Recent Advances in Nanomaterial‐Based Nanoplatforms for Chemodynamic Cancer Therapy

AbstractTriggered by the endogenous chemical energy in the tumor microenvironment (TME), chemodynamic therapy (CDT) as an emerging non‐exogenous stimulant therapeutic modality has received increasing attention in recent years. The chemodynamic agents can convert internal hydrogen peroxide (H2O2) into the lethal reactive oxygen species (ROS) hydroxyl radicals (•OH) for oncotherapy. Compared with other therapeutic modalities, CDT possesses many notable advantages, such as tumor‐specific, highly selective, fewer systemic side effects, and no need for external stimulation. Nevertheless, mild acid pH, low H2O2 content, and overexpressed reducing substance in TME severely suppressed the CDT efficiency. With the rapid development of nanotechnology, some kinds of nanomaterials have been utilized with improved CDT efficiency. In particular, the excellent photo‐, ultrasound‐, magnetic‐, and other stimuli‐response properties of nanomaterials make it possible for combination cancer therapy of CDT with other therapeutic modalities, and it has shown superior anti‐cancer activity than monotherapies. Therefore, it is necessary to summarize the application of nanomaterial‐based chemodynamic cancer therapy. In this review, the various nanomaterials‐based nanoplatforms for CDT and its combinational therapies are summarized and discussed, aiming to provide inspiration for the design of better‐quality agents to promote the CDT development and lay the foundation for its future conversion to clinical applications.

Interrogating the Effects of Hydrogen on the Behavior of Planar Deformation Bands in Austenitic Stainless Steel

The effects of internal hydrogen on the deformation microstructures of 304L austenitic stainless steel have been characterized using electron backscattered diffraction (EBSD), transmission Kikuchi diffraction (TKD), high-resolution scanning transmission electron microscopy (HRSTEM), and nanoprobe diffraction. Samples, both thermally precharged with hydrogen and without thermal precharging, were subjected to tensile deformation of 5 and 20 pct true strain followed by multiple microscopic interrogations. Internal hydrogen produced widespread stacking faults within the as-forged initially unstrained material. While planar deformation bands developed with tensile strain in both the hydrogen-precharged and non-precharged material, the character of these bands changed with the presence of internal hydrogen. As shown by nanobeam diffraction and HRSTEM observations, in the absence of internal hydrogen, the bands were predominantly composed of twins, whereas for samples deformed in the presence of internal hydrogen, ε-martensite became more pronounced and the density of deformation bands increased. For the 20 pct strain condition, α′-martensite was observed at the intersection of ε-martensite bands in hydrogen-precharged samples, whereas in non-precharged samples α′-martensite was only observed along grain boundaries. We hypothesize that the increased prevalence of α′-martensite is a secondary effect of increased ε-martensite and deformation band density due to internal hydrogen and is not a signature of internal hydrogen itself.

Application of glycerol on bioplastic based carrageenan waste cellulose on biodegradability and mechanical properties bioplastic

The carrageenan industrial waste materials can be used bioplastic biodegradable production because has high cellulose content 71.38%. Bioplastics can easily degraded and flexible, it is necessary to add glycerol plasticizers, that can reduce internal hydrogen in intermolecular bonds that affected biodegradability and mechanical properties of bioplastics. This study aimed was to analyze the effect of glycerol application as plasticizers on bioplastics based carrageenan waste cellulose on biodegradability and analysis the best concentration of glycerol on bioplastics to get biodegradation standards and mechanical properties based on the review article. This research was experimental in testing biodegradability of carrageenan waste cellulose bioplastic with the addition of glycerol (1; 3; 5; 7% v/v) and review article on the mechanical properties of bioplastics and waste cellulose content. Experimental research used ANAVA data analysis and followed by DMRT. The results of this study were indicated that the glycerol has significantly effect (P <0.05) on the ability of biodegradation with the highest value of 39.20 + 0.87% - 40.34 + 0.78% for seven days at a concentration of 5-7%. Based on the review article, the concentration of glycerol on bioplastics cellulose that suitable with biodegradation standards and mechanical properties of bioplastics is 5%

Insight into the reaction mechanism over PMoA for low temperature NH3-SCR: A combined In-situ DRIFTs and DFT transition state calculations

Phosphomolybdic acid catalyst (PMoA/TiO2) is a promising catalyst for selective catalytic reduction of NOx with NH3 (NH3-SCR) due to its strong acidity and excellent redox property. This work presents the NH3-SCR reaction mechanism by In-situ diffuse reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTs) and density functional theory (DFT). In-situ DRIFTs results indicated that the NH3-SCR performance over PMoA/TiO2 followed both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. The reaction pathway, intermediate, transition state and energy barrier over PMoA to complete NH3-SCR reaction were calculated by DFT. The results showed that the catalytic cycle includes foundational reaction (NH3 + NO reaction) and regenerative reaction (NH3 + NO2 reaction). NH2, NH2NO, HNNOH and HO2NNH species were the key intermediates. In the foundational reactions, NO2 played an important role in the removal of remaining H atoms. The NH3 dissociation on Lewis acid site, the internal hydrogen transfer on Brønsted acid site and the formation of HO2NNH species were the rate-controlling steps. The catalytic cycle of NH3-SCR over PMoA consists of standard SCR and fast SCR.

Hydroxylation and sodium intercalation on g-C3N4 for photocatalytic removal of gaseous formaldehyde

In this study, hydroxyl-modified/Na-intercalated g-C3N4 was used as an effective material for the removal of gaseous formaldehyde (HCHO) through adsorption and photocatalytic oxidation. In a simple reflux reaction using different NaOH concentrations, the surface-grafted hydroxyl (‒OH) groups of g-C3N4 formed internal hydrogen bonds with gaseous HCHO, while the Na atoms intercalated into the layered structure of g-C3N4 to create an electron transfer path (layer‒Na‒layer) to improve charge separation for photocatalytic oxidation. The hydroxylation as well as Na intercalation of g-C3N4 significantly increased its HCHO removal efficiency compared with that of bare g-C3N4. The HCHO removal capacity of the modified g-C3N4 reached approximately 0.12 ppm g−1 min−1, which was twice that of bare g-C3N4 (<0.06 ppm g−1 min−1). Moreover, the modified g-C3N4 was reused at least thrice without any decline in activity. This work provides a facile, simple, and fast approach to the modification of g-C3N4 via hydroxylation and Na intercalation to enhance HCHO adsorption as well as electron transfer, rendering it a promising material for indoor HCHO removal.

Influence of non-homogeneous microstructure on hydrogen diffusion and trapping simulations near a crack tip in a welded joint

Hydrogen assisted fracture near welds is the result of a combination of microstructural changes and the accumulation of hydrogen. With the aim of predicting local hydrogen concentrations, hydrogen redistribution near a crack tip is simulated using a Boundary Layer approach and diffusion modelling is modified by trapping phenomena. The simulated non-homogeneous geometry includes layers that reproduce weld metal, heat affected zones and base metal of a 2.25Cr-1Mo steel; mechanical and diffusion properties have been extracted from references. The hydrogen transport model here considered involves a stress dependency that affects local concentrations; thus, the possible interaction between constraint effects associated to a graded material with hydrogen entry and transport is studied. Results show that the constraint effect is not significative for the loading and for the widths assigned to the weld and the heat affected zones (2.5 to 5 mm); however, for the HAZ-centred crack, a higher hydrostatic peak and the corresponding increase in lattice hydrogen are found. A two-type trapping process is also simulated to reproduce simultaneously the effect of dislocation trapping and microstructure delayed diffusion. Hydrogen is weakly trapped in dislocations and it is added to the lattice concentration to obtain a measure of diffusible hydrogen near a crack tip while effective diffusivity is strongly reduced by deeply trapped hydrogen. Differences between environmental or internal hydrogen sources are expected to be more accurately captured because stress-dependent boundary conditions have been implemented for hydrogen uptake.

Effect of internal hydrogen on low- and high-cycle fatigue life properties and the role of strain-induced martensitic transformation and solid solution strengthening

Effect of internal hydrogen on low- and high-cycle fatigue life properties and the role of strain-induced martensitic transformation and solid solution strengthening

Primary photodissociation mechanisms of pyruvic acid on S1: observation of methylhydroxycarbene and its chemical reaction in the gas phase.

Pyruvic acid, a representative alpha-keto carboxylic acid, is one of the few organic molecules destroyed in the troposphere by solar radiation rather than by reactions with free radicals. To date, only its stable final products were identified, often with contribution from secondary chemistry, making it difficult to elucidate photodissociation mechanisms following excitation to the lowest singlet excited-state (S1) and the role of the internal hydrogen bond in the most-stable Tc conformer. Using multiplexed photoionization mass spectrometry we report the first direct experimental evidence, via the observation of singlet methylhydroxycarbene (MHC) following 351 nm excitation, supporting the decarboxylation mechanism previously proposed. Decarboxylation to MHC + CO2 represents 97-100% of product branching at 351 nm. We observe vinyl alcohol and acetaldehyde, which we attribute to isomerization of MHC. We also observe a 3 ± 2% yield of the Norrish Type I photoproducts CH3CO + DOCO, but only from d1-pyruvic acid. At 4 Torr pressure, we measure a photodissociation quantum yield of 1.0+0-0.4, consistent with IUPAC recommendations. However, our measured product branching fractions disagree with IUPAC. In light of previous calculations, these results support a mechanism in which hydrogen transfer on the S1 excited state occurs at least partially by tunneling, in competition with intersystem crossing to the T1 state. We present the first evidence of a bimolecular reaction of MHC in the gas phase, where MHC reacts with pyruvic acid to produce a C4H8O2 product. This observation implies that some MHC produced from pyruvic acid in Earth's troposphere will be stabilized and participate in chemical reactions with O2 and H2O, and should be considered in atmospheric modeling.

Development of a New Cold Metal Transfer Arc Additive Die Manufacturing Process

Due to its high efficiency, cold metal transfer (CMT) arc additive manufacturing presents considerable potential in the aluminium alloy additive manufacturing industry. However, during CMT arc additive manufacturing, the surrounding air environment promotes the lateral flow of liquid aluminium and the instability of the molten pool, reduces the surface quality and material utilisation of deposition walls, and causes internal hydrogen pores and coarse columnar grains, which negatively affect the structure and mechanical properties of the deposition walls. This study developed a CMT arc additive die manufacturing process to control the substrate material and deposition path to improve the physical properties of the deposition wall. The experimental results indicated that the copper plates can affect molten pool flow and material formation in the additive process, minimise hydrogen pores, and refine columnar grains. The porosity dropped from 2.03% to 0.93%, and the average grain size decreased from 16.2 ± 1.4 to 13.6 ± 1.3 μm, thereby enhancing the structure and mechanical properties of the deposition wall to attain standard additive manufacturing products.

Models of hydrogen influence on the mechanical properties of metals and alloys

The article yields a survey of the key models of mechanics that are used to describe the effects of hydrogen embrittlement, hydrogen cracking, and hydrogen-induced destruction. The main attention is paid to models which are used to calculate the stress-strain state of metal samples, parts and machine components and have the potential for specific engineering applications. From a mechanical perspective, the effect of hydrogen on the material properties is a classic problem of the influence of a small parameter, since the hydrogen concentrations critical for the strength and ductility of metals are usually small. In the vast majority of models this effect is reduced to the hydrogen redistribution within the material volume and localization of concentrations in the critical fracture zones. The authors identified four main approaches that allow one to take into account the influence of a small parameter: (i) hydrogen-enhanced decohesion (HEDE), (ii) hydrogen-enhanced localized plasticity (HELP), (iii) account for additional internal pressure due to the hydrogen dissolved in metals, and (iv) bi-continuum approach that takes into account the internal hydrogen pressure and weakening of material in the framework of a special model of a solid. The links between the main approaches are established. Systematization of publications was carried out, similarities and differences in the description of the internal transport and accumulation of hydrogen in metals are highlighted. It is indicated that the predominant number of publications is devoted to the HEDE model, but so far there is no published data on the application of this model to real problems of engineering practice; only modeling the results of mechanical tests of cylindrical and prismatic samples were considered. In fact, other less popular approaches have more practical applications. The main unresolved issue in the verification of all models is the local concentration of hydrogen, which is a source of premature destruction of metals under load. All the methods for measuring local concentrations are indirect. Even in the case of applying sophisticated physical methods, mechanical surface preparation is required, which destroys the initial natural concentration of hydrogen. The lack of reliable data on the distribution of hydrogen concentration excludes the possibility of unambiguously determination of all the model parameters. On the one hand, it allows fitting to any experimental data, and on the other hand, it reduces the predictive engineering value of all models, since a qualitative fitting is not sufficient for engineering strength analysis.

Fracture toughness of coarse-grain heat affected zone of quenched and tempered CrMo steels with internal hydrogen: Fracture micromechanisms

The determination of fracture behaviour of welds in presence of internal hydrogen is essential for the integrity assessment of CrMo vessels and pipes working under high hydrogen pressures. Homogeneous coarse-grain tempered bainitic/martensitic microstructures were obtained in 42CrMo4 and 2.25Cr1Mo steels by means of laboratory heat treatments in order to reproduce the coarse grain heat affected zone (CGHAZs) of real welds. Afterwards, the fracture toughness behaviour of the simulated CGHAZs was assessed under low displacement rate J-fracture tests, using pre-charged (in hydrogen gas) CT specimens. The hydrogen embrittlement (HE) experienced by the CGHAZs of both steels was considerably greater than in the base steels. The greater hardness, i.e. higher dislocation density, characteristic of the CGHAZ microstructures, explains the more strongly trapped hydrogen, and hence the sharper drop in the fracture toughness, also associated to an increase of intergranular fracture micromechanisms. Scanning electron microscopy examination of the fracture surfaces revealed the action of hydrogen-enhanced localized plasticity (HELP) mediated hydrogen-enhanced decohesion (HEDE) micromechanism, in which HELP took place first, providing enough hydrogen in the process zone to modify the local resistance, and eventually weakening the cohesion of the internal interfaces, HEDE.