Gas Fusion Research Articles

Vaporization enthalpies of self-associated aromatic compounds at 298.15 K: A review of existing data and the features of heat capacity correction. Part III. Polyphenols, polyanilines and aminophenols

The experimental data on the phase transition enthalpies and heat capacities of numerous polyphenols, polyanilines and aminophenols in the condensed and ideal gas state were analyzed to obtain the reliable values at 298.15 K. For this purpose, we combined experimental data on the crystal, liquid, and ideal gas heat capacities and fusion, sublimation and vaporization enthalpies. Significant part of these data, including the ideal gas heat capacities of 16 molecules, vapor pressures and vaporization enthalpies of 1,3-diaminobenzene and 1,6-dihydroxynaphthalene, were obtained in this work. A modified approach for the estimation of the temperature dependence of vaporization enthalpies of polyphenols, polyanilines and aminophenols showing performance competitive with the experimental one was proposed based on the analysis performed.

Fabrication of α-W and β-W Films By Using CsF–CsCl–WO3 Molten Salt: Effect of Oxygen Contents in W Films

Electrodeposition of W films in CsF–CsCl eutectic melts was investigated after adding 2.0 mol% of WO3 at 773–973 K. The oxygen content in W films electrodeposited at various temperatures was analyzed using inert gas fusion and non-dispersive infrared spectroscopy (NDIR). Oxygen contents in the W films gradually decreased from 6.65 at% to 0.24 at% as the bath temperature increased from 773 K to 923 K along with the crystal phase change from β-W to α-W, confirmed by X-ray diffractometry (XRD). Then, vacuum annealing treatment was performed for the electrodeposited β-W films. The crystal phase was transformed to pure α-W after annealing at 973 K for 3 h and the oxygen content in W films decreased from 1.82 at% to 0.38 at%. Finally, based on the above findings, we provide a promising two-step method for preparing mirror-like and dense α-W films.

Investigation of the cross sections for electron collision ionization of complex molecules

AbstractAn accurate and computationally efficient determination of the cross sections for electron collision ionization of molecules has various applications, such as plasma physics and atmospheric science. In the case of large molecules, ab initio calculations are often difficult and time‐consuming. Here, we develop a feed forward neural network to predict the electron impact ionization cross sections of complex molecules. The training (predicting) set in the method consists of a series of theoretical ionization cross sections for small (large) molecules obtained from the combined model, which integrates the Binary‐Encounter‐Bethe and Deutsch‐Märk models. Several complex systems or targets involving electron collision ionization are evaluated, including molecules such as CH, CH, CH, CH, C, CHO, and CHO. The root mean square errors of the trained and predicted cross sections by the neural network (compared to the values from the combined model) are found to be approximately .0086 and .0930 (in 10 cm), respectively, (using the CHO molecule as an example), indicating our results are very high accuracy. The excellent agreement between the predicted values and the actual values indicates that the neural network is a practical and powerful tool for determining the electron collision ionization cross sections of complex molecules and can provide valuable insights into the dynamics process. Apart from its fundamental importance, this study has far‐reaching implications for gas discharge, low‐temperature plasmas, and fusion edge plasmas and so forth.

A roadmap for tailoring the microstructure and mechanical properties of additively manufactured commercially-pure titanium

In recent years there has been a growing interest in using additive manufacturing to produce near net-shape parts from titanium alloys. Most of these studies have focused on the fabrication of various high-strength alloys such as Ti5553 and Ti–6Al–4V, but there is also a desire to produce parts out of lower-strength and higher elasticity alloys such as commercially pure titanium (CP–Ti). In this work, we have shown the effects on various properties of CP-Ti Grade 2 produced via the Laser Powder Bed Fusion (L-PBF) manufacturing process and subsequent heat treatments. Samples with 99.98 % density were produced. Microstructure and phase evolution was characterized by X-ray and electron backscatter diffraction and polarized light microscopy. Oxygen was found to be incorporated during manufacture and processing by Inert Gas Fusion (IGF). Heat-treatment of the samples resulted in recrystallization of the acicular microstructure. By testing the mechanical properties throughout the recrystallization temperatures, it was observed that the grain recrystallization lead to a reduction in mechanical strength without a significant improvement in ductility, therefore making a low temperature heat-treatment that retains the AM microstructure an interesting alternative to strengthen CP-Ti.

In Situ Measurement of Hydrogen Absorption into Copper-Coated Titanium Using Neutron Reflectometry and Electrochemical Impedance Spectroscopy

We set out to investigate the possibility that a small amount of hydrogen, generated by sulfide-driven corrosion or radiolytic processes, might be absorbed into the copper coating proposed for use as corrosion protection for the used nuclear fuel containers (UFCs) to be stored in a deep geological repository (DGR) in Canada. Hydrogen absorption may have the potential to alter the mechanical properties of the copper coating. This contribution discusses our initial study, using in situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS), of hydrogen absorption into a 50-nm layer of copper coated onto 4 nm of Ti on a Si single-crystal substrate. In situ NR-EIS experiments detected no increase in the hydrogen content within the copper layer of the copper-titanium thin film following 55 h of polarization in deoxygenated 0.1 M NaCl solution at pH 9, at potentials ranging from −444 mV/SCE to −1300 mV/SCE (detection limit ~2 at.%). However, these NR results showed that hydrogen can be absorbed into copper when the latter is cathodically polarized below about ─900 mV/SCE, which is the experimentally measured potential threshold for the hydrogen evolution reaction (HER) under these conditions. Although hydrogen did not accumulate in the outer Cu layer, our experiments revealed that the absorbed hydrogen quickly traversed the Cu layer to concentrate in the underlying titanium layer, which favours absorbed hydrogen. This observation is consistent with hydrogen uptake measured using inert gas fusion analysis on oxygen-free, phosphorus-doped (OFP) copper, which showed that in the absence of hydrogen recombination inhibitors (e.g., As(III)), only a small increase of 22 wt. ppm hydrogen was absorbed into the copper after 24 h at E = −1300 mV/SCE, and no increase in absorbed hydrogen occurred at potentials of −1100 mV/SCE or more positive. The initial absorption efficiency for electrolytically produced hydrogen atoms at the copper surface was determined to be 3.2%, suggesting that there may be an upper limit for hydrogen uptake by the copper coating of the UFC, although studies on 3 mm copper-coated steel samples representative of UFC materials will be required to confirm that. This result supports the prediction that hydrogen absorption is unlikely to lead to any failure of the copper barrier within a proposed DGR, in which it will not be possible to achieve such negative electrochemical potentials. Intended future research using in situ NR-EIS to study hydrogen absorption during the corrosion of copper thin films by HS⁻ ions and further studies on hydrogen absorption into 3-mm-thick copper-coated steel samples will help to validate these conclusions.

Measurement of liquidus in metal-rich region of lanthanoid-oxygen binary systems and the thermodynamic evaluation

In this study, the solubilities of oxygen in molten La, Gd, Tb, Ho, and Er metals were measured and the oxide phases in equilibrium with each of these lanthanoid metals were identified to systematically determine the liquidus of lanthanoid-oxygen systems in the metal-rich region. The molten lanthanoid metal and lanthanoid oxide pellets were equilibrated at 1573–1873 K and then quenched. The oxygen concentration in the quenched metals was measured using inert gas fusion infrared absorption spectroscopy to determine the oxygen solubilities of molten lanthanoid metals. The crystal structures of the quenched lanthanoid oxide pellets were analyzed using XRD to identify the equilibrium oxide phases, which were identified as the sesquioxides of each lanthanoid element. Furthermore, the Gibbs free energies of the liquid phases of the Ln-O (Ln = La, Pr, Gd, Tb, Dy, Ho, Er) systems were evaluated using the CALPHAD method and thermodynamic software Pandat based on the oxygen solubilities of molten La, Gd, Tb, Ho, and Er metals measured in this study and those of Pr and Dy reported in previous studies.

Method for the Determination of Oxygen in FLiBe via Inert Gas Fusion.

In nuclear reactors that use molten fluoride salts, either as coolants or as the medium for the fuel, the purity of the salts is critical for controlling salt chemistry and mitigating corrosion. Water is a particularly important contaminant in this regard, as it participates in a number of important corrosion reactions, so the careful measurement of oxygen, which is principally present in the salts due to water contamination, is a critical step in salt characterization. Here, we present an analytical method for quantifying oxygen contamination in Li2BeF4 (FLiBe), a technologically important and suitably representative fluoride salt, with a detection limit of 22 μg of oxygen, or 110 ppm in a 200 mg sample. To test the method, four FLiBe samples from different batches were tested. Two of these showed oxygen concentrations below the method detection limit, while two showed concentrations above it. In particular, the difference in the oxygen concentration between purified and un-purified batches of material from Kairos Power showed the efficacy of this method in characterizing the degree of oxygen removal obtained from purification methods.

Hydrogen charging of carbon and low alloy steel by electrochemical methods

Atomic hydrogen can be the result of different processes like electroplating, chemical and electrochemical pickling treatments, in welding or by cathodic processes in corrosive fluids. Moreover, adsorption of atomic hydrogen can affect materials in contact with high pressure gaseous hydrogen. Once entered the material, atomic hydrogen interacts with the metal structure and may produce a “damage” of various forms, such as Hydrogen Induced Cracking (HIC), delayed fracture, blistering and hydrogen embrittlement. In particular, when H2S is present (“sour service”), metallic materials, such as carbon and low alloy steels, may suffer hydrogen damage and hydrogen embrittlement. Sour service materials must be used in compliance with international accepted standards, used worldwide in oil and gas activities, when fluids are classified as sour. The present study has been carried out in order to set up an electrochemical method to charge with hydrogen two typical pipeline materials, carbon and low alloy steels. The reason of the use of an electrochemical method is to avoid any critical conditions from the point of view of preparation, safety and disposal. Hydrogen content in the specimens was measured by two different methods: hot glycerol bath and Inert Gas Fusion (IGF) analysis. Hydrogen content in the specimens is about 0.6–2 ppm; mechanical performances were assessed by means of J integral tests: a pronounced decrease of fracture toughness was observed for H charged specimens.Graphical

Development of a Primary Iridium Solution Standard Traceable to the International System of Units.

The purpose of this work was to develop a primary solution standard for iridium (Ir) that is directly traceable to the International System of Units (SI). The candidate starting material was ammonium hexachloroiridate hydrate, ((NH4)3IrCl6·3H2O), the Ir salt. The SI traceability of the Ir salt was established by the gravimetric reduction (GR) of the salt to the metal under H2. GR traces the results of the analysis directly to the SI base unit of mass, the kg. The GR was also performed on high-purity Ir metal powder, an independent source of Ir, used as a comparison material for the salt. A method for dissolving the Ir metal was developed by modifying information found in the literature. Trace metallic impurities (TMI) analysis was performed on the Ir salt using ICP-OES and ICP-MS. Inert gas fusion (IGF) analysis provided data for the O, N, and H content of the gravimetrically reduced and unreduced Ir metals. The combined results of the TMI and IGF analyses provided the purity data, a required component for the claim to SI traceability. Solution standards were gravimetrically prepared from the candidate SI traceable Ir salt. Solution standards for comparison were prepared from the dissolved, unreduced high-purity Ir metal powder. These solutions were compared by a high-precision ICP-OES method. Agreement in the results between these Ir solutions, with uncertainty estimates calculated by error budget analysis, confirmed the accuracy of the Ir assay in the candidate SI traceable Ir salt, (NH4)3IrCl6·3H2O, thus confirming the concentrations and uncertainties for the primary SI traceable Ir solution standards made from the (NH4)3IrCl6·3H2O.

Characterization of Virgin, Re-used, and Oxygen-reduced Copper Powders processed by the Plasma Spheroidization Process

Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and assess oxygen reduction of the powder lots given their initial oxygen contents. Also, to investigate the impact of re-spheroidization on powder properties, the second round of spheroidization was performed on the already used-spheroidized powder. The impact of powder type on powder sphericity and particle size distribution was evaluated using the image analysis of scanning electron microscope (SEM) micrographs and laser diffraction, respectively. The spheroidized powder showed higher sphericity and more uniform particle size distribution overall. Depending on the powder collection bin, second round of spheroidization affected the powder sphericity differently. The possibility of deploying the plasma spheroidization process as an alternative oxygen-reduction technique was also investigated through tracking the powders’ oxygen content using inert gas fusion method before and after the spheroidization. The plasma spheroidized powder showed less oxygen content than the hydrogen-treated powder. The second round of spheroidization caused no change in oxygen content. The correlation between oxygen-reduction and created cracks was discussed and compared between plasma spheroidization and hydrogen-treatment. The plasma spheroidization process created a powder with higher sphericity, uniform particle size, and less oxygen content.

Simultaneous Analysis of Soluble and Insoluble Oxygen Contents in Al-Killed Steels of Various C Contents and Supersaturation Phenomena in the Steel

Soluble and insoluble O contents ([S. O] and [I. O], respectively) in Al-killed steels of various C contents (0 to ~2 mass pct.) were simultaneously measured using “two-stage” inert gas fusion infrared absorptiometry, where majority of the inclusions was alumina. Several steel specimens were used for the O content analysis where the specimens were either taken from a steel plant or prepared in this laboratory. In addition to this, several pretreatment methods of the specimens were tested in order to provide reliable analysis results. It was found that mechanical grinding of the specimen’s surface should be carefully carried out in order not to induce unwanted surface oxidation. This resulted in overestimation of the O content of the specimen. [S. O] and [I. O] in the steel specimens were successfully analyzed using the “two-stage” gas fusion method in the context of inert gas fusion infrared absorptiometry. Considerable portion of total O content ([T. O] = [S. O] + [I. O]) was the [S. O], which was higher than the equilibrium O content of the known Al deoxidation equilibria. Therefore, the supersaturation in the Al deoxidation was confirmed. The analyzed [I. O] was independently validated by measuring area of the exposed alumina inclusions on the polished section of the specimen using SEM. It was also found that increasing C content in the steel lowered the [S. O] while [I. O] hardly changed. It is concluded that C in the steel, mechanical stirring, and remelting, could relieve the supersaturation.

Adsorption of heхavalent chromium on mechanically activated graphite

Mechanical activation of spectrally pure graphite was carried out in a high-energy planetary mill. Changes in the structure and physicochemical properties caused by this modification are shown by SEM, XRD, Raman spectroscopy, XPS, N2 adsorption-desorption, and inert gas fusion methods. Because of the mechanical activation, a decrease in crystallite size of the graphite and the oxidation occurred; it began to exhibit sorption properties with respect to Cr(VI) ions. The optimal conditions were found for removing more than 99% of Cr(VI) from the 50 mg∙l−1 aqueous solutions. In an acetate buffer solution with pH 6.3 after 1 h of heating at 90°C, the Langmuir adsorption capacity for chromium on this sorbent is 14.7 mg∙g−1. Thermodynamic characteristics of the adsorption were determined; they show that the process is spontaneous and endothermic. It was found that only incomplete desorption of chromium from the surface of the modified graphite is possible using concentrated NaOH solutions. An assumption was made about a mixed mechanism of chromium adsorption, including partial reduction of Cr(VI) to Cr(III), anionic adsorption of Cr(VI) ions through electrostatic interaction, and the formation of an insoluble chemical compound of Cr(III) on the surface of the mechanically activated graphite. The sorbent was tested on a real sample of wastewater from bichromate production, after adsorption hexavalent chromium was not detected in the water.

Assessment of intra-build variations in tensile strength in electron beam powder-bed fusion Ti–6AL–4V part 1: Effects of build height

In this work, rectangular blocks of electron beam powder-bed fusion (PBF-EB) additively manufactured (AM) Ti–6Al–4V were built, such that a total of 68 mini-tensile test coupons could be extracted for mechanical testing over a range of build height and build plate locations. These as-built tensile test coupons were uniaxially tested to fracture and subsequently studied via scanning electron microscopy, micro X-ray computed tomography, and inert gas fusion chemical analysis to systematically study the intra-build variations in tensile properties, microstructure, porosity, and chemistry. A strong correlation was observed between YS and build height, where YS was observed to decrease with increasing build height, up to 35 mm. There were no significant contributions to this variation in yield strength (YS) from build location, porosity, grain size, or crystallographic texture. Inert gas fusion oxygen measurements reveal the same trend, suggesting that oxygen content variation as a function of build height is contributing to the observed YS variation. The source of the oxygen content variation is thought to be a transient source of oxygen, such as moisture in the powder and build chamber. The establishment of this oxygen variation and its correlation to tensile properties motivates and facilitates improvements to PBF-EB Ti–6Al–4V processing, including powder mixing and handling.

Assessment of intra-build variations in tensile strength in electron beam powder-bed fusion Ti–6Al–4V part 2: Effects of powder mixing

In Part 2 of this paper series, high-throughput tensile testing and characterization of porosity, microstructure, and oxygen content was carried out on Ti–6Al–4V samples that were fabricated via electron beam powder-bed fusion (PBF-EB) to test our hypothesis that current industrial powder mixing strategies lead to stochastic chemistry content and tensile property variation throughout a given build. Fifteen rectangular blocks were built at locations across the entire build plate and machined into high-throughput tensile racks that contained 25 mini tensile coupons each (375 total specimens). There was a spread of 138.9 MPa in yield strength (YS) across all specimens. Considering the YS spread was only 74.2 MPa for a virgin build with no mixing, as detailed in Part 1, the difference between these two YS ranges is expected to be attributed to mixing. To determine the cause for this observed spread in YS, systematic investigation of porosity, microstructure, and oxygen content was performed via scanning electron microscopy (SEM), micro X-ray computed tomography (μXCT), inert gas fusion, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The large variation in YS for these specimens could not be attributed to internal porosity, fracture surface porosity, α-lath thickness, or crystallographic texture. Inert gas fusion measurements indicated large, stochastic variation in oxygen content, and measurements via ToF-SIMS near the fracture surfaces indicate localized chemistry variations that could be responsible for the large variations in tensile properties, specifically the yield strength. Specific alternative powder mixing and reuse methodologies are proposed to mitigate undesirable chemistry and tensile property variation within PBF-EB Ti–6Al–4V.

Thermodynamic Basis of Isothermal Carbothermic Reduction of Oxide in Liquid Steel for Simultaneous Analysis of Soluble/Insoluble Oxygen Contents in the Steel Specimens

Oxygen in liquid steel exists as soluble O (chemically dissolved in the steel matrix) and insoluble O (physically dispersed as the oxide inclusion). To measure the soluble O content ([S.O]) and the insoluble O content ([I.O]), both in the context of gas fusion analysis technique such as inert gas fusion infrared absorption method, it is necessary to melt the specimen under a C saturation condition in a “two-stage” isothermal heating mode. The first stage is carried out at a low temperature (TL), where only soluble O is extracted as CO(g). The second stage is subsequently carried out at a high temperature (TH), where the oxide inclusion is reduced by a carbothermic reaction. Therefore, it is necessary to identify the carbothermic reduction temperature of the oxide inclusion in the liquid steel at the C saturation (\( T_{{{\text{M}}_{x} {\text{O}}_{y} }}^{{{\text{Fe}}}} \)). A series of CALPHAD-type thermodynamic calculations were carried out to estimate the temperature of each oxide inclusion (Al2O3, FetO, SiO2, CaO, and MgO). It was found that the temperature depends on the metal content ([pct M]) and total pressure (P) inside the gas fusion chamber: increasing [pct M] or P increases \( T_{{{\text{M}}_{x} {\text{O}}_{y} }}^{{{\text{Fe}}}} \). The proposed method may be applied for the steel systems containing those inclusions except for FetO. In the case of Al2O3 inclusion containing steel ([pct Al] = 0.04), for example, \( T_{{{\text{Al}}_{2} {\text{O}}_{3} }}^{{{\text{Fe}}}} \), lies in the range of 1791 K (1518 °C) to 1838 K (1565 °C) depending on P inside the gas fusion chamber. Possible range of the \( T_{{{\text{M}}_{x} {\text{O}}_{y}}}^{{{\text{Fe}}}}\) is reported.

Analysis for Gas in Transformer Oil based on improved GM (1, N) Grey

Based on the traditional gray GM (1, N) model, with seven kinds of gas fusion in transformer oil predicted, the actual detection times for the gas is less, the sequence accuracy is greatly reduced with an large error, and it will not conform to the standard judgment for the smooth curve. Therefore, an adaptive regression algorithm is proposed to revise each calculation result of its GM model to modify the model error. Through simulation, the sequence curves of the N data by error correction are obviously closer with a greater correlation degree. The improved gray prediction model can effectively improve the accuracy of traditional GM (1, N).

Tracing an Osmium Solution Standard to the International System of Units (SI).

The purpose of this work was to develop an accurate osmium (Os) solution standard that is traceable to the International System of Units, the SI. A gravimetric reduction (GR) method was developed to accurately assay the Os in ammonium hexachloroosmate salt, (NH4)2OsCl6, the chosen starting material for the Os solution standard. This GR method was also applied to -200 mesh high-purity Os metal powder, which served as an independent source of Os for comparison. An alkali fusion method was developed to create water-soluble salts from the Os metal GR products of both the (NH4)2OsCl6 and -200 mesh high-purity Os metal powder. Quantitatively prepared Os solutions from each of these water-soluble salts were compared by inductively coupled plasma spectrometry, ICP-OES. The purities of the Os starting materials were determined by quantitatively performed trace metallic impurities analysis, by ICP-OES and ICP-MS; the O, N, and H impurities were determined by inert gas fusion analysis. The percent purities of the starting materials were applied as corrections to the Os assay results obtained by GR. The agreement between these Os solutions, corrected for random and systematic errors by error budget analysis, confirmed the accuracy of the Os assay in the (NH4)2OsCl6. The SI traceability of the Os assay in the (NH4)2OsCl6 salt was established through the GR procedure and the purity analysis of this material. An SI traceable Os solution standard was gravimetrically prepared from this batch of (NH4)2OsCl6, based on the accurate Os assay and the percent purity of the starting material.

Mode transition in 1D He plasma jet arrays dominated by hydrodynamic interaction

As an emerging technology for flexibly generating large-area atmospheric plasma, jet arrays are facing an urgent problem to control discharge modes caused by jet-to-jet interactions, apart from issues of stability and uniformity. Here, two modes in one-dimensional ns-pulsed He plasma jet arrays are reported, namely coupling and collimated modes. Discharge characteristics and transition rules of the two modes are explored by optical, electrical, spatial-temporal resolved and Schlieren methods. Results reveal that the coupling mode appears only when multiple conditions are satisfied, including low gas flow rate, high voltage frequency and small jet separation. Fluid dynamics and intensified charged-coupled device images prove that the mode transition mainly depends on the hydrodynamic interaction, which exceeds the effect of electrostatic repellence between ionization waves. Shrinkage of He flows is visualized to be enhanced at coupling mode, contributing to inward deflection of outmost plasma jets. Eddies on both sides of jet array and low-pressure regions near nozzles are generated by electric winds, promoting the transversal momentum transfer and gas fusion among adjacent He flows, thus tending to jet couplings. Some fresh insights are provided in this work about jet coupling and generation of controllable large-area plasma sources. The results could help to understand the importance of hydrodynamic interaction among proximal plasma jets, and plasma action on adjacent gas flows.

Mechanical and corrosion properties of gas and water atomized laser-powder bed fusion fabricated 25Cr7Ni stainless steel

Several components fabricated from 25Cr7Ni stainless steel are widely used in industry owing to its beneficial combination of high strength and superior corrosion resistance. There are very few studies reported in the literature on the laser-powder bed fusion (L-PBF) fabricated properties of 25Cr7Ni stainless steel. The current study is focused on understanding the effect of powder attributes and chemical composition on the properties of L-PBF processed 25Cr7Ni stainless steel. L-PBF fabricated samples made from gas and water atomized 25Cr7Ni powders were evaluated in the present study for densification, mechanical and corrosion properties. The L-PBF samples processed from gas atomized powders displayed higher densification, tensile strength and superior corrosion resistance compared to samples made from water atomized powders. The superior corrosion resistance of L-PBF samples made from gas atomized powders is attributed to the presence of austenite phase in microstructure. The corrosion resistance of L-PBF gas atomized powder samples were comparable to the wrought-annealed 25Cr7Ni stainless steel.

Analysis of Hydrogen in Inorganic Materials and Coatings: A Critical Review

The currently used bulk analysis and depth profiling methods for hydrogen in inorganic materials and inorganic coatings are reviewed. Bulk analysis of hydrogen is based on fusion of macroscopic samples in an inert gas and the detection of the thereby released gaseous H2 using inert gas fusion (IGF) and thermal desorption spectroscopy (TDS). They offer excellent accuracy and sensitivity. Depth profiling methods involve glow discharge optical emission spectroscopy and mass spectrometry (GDOES and GDMS), laser-induced breakdown spectroscopy (LIBS), secondary ion mass spectrometry (SIMS), nuclear reaction analysis (NRA), and elastic recoil detection analysis (ERDA). The principles of all these methods are explained in terms of the methodology, calibration procedures, analytical performance, and major application areas. The synergies and the complementarity of various methods of hydrogen analysis are described. The existing literature about these methods is critically evaluated, and major papers concerning each method are listed.