Glow-discharge Spectroscopy Research Articles

Transition rate diagrams — A new approach to the study of selective excitation processes: The spectrum of manganese in a Grimm-type glow discharge

The emission spectra of manganese observed using a Grimm-type glow discharge in pure argon, argon with 0.3% v/v hydrogen and pure neon were studied in order to identify major excitation and ionization processes of manganese in the plasma. A new procedure is proposed, in which each observed emission line is associated with the corresponding transition between different states of the Mn atom or Mn ion, and, by considering all the observed transitions from and into a specific state, a measure of the total rate is determined at which this state is radiatively populated and depopulated. These resulting population/depopulation rates are then plotted as function of level energy. Such plots, called here “transition rate diagrams”, show the role of individual states in the formation of the observed spectrum and can be used to identify possible selective excitation processes. Also, cascade excitation by radiative decay of higher excited states can be conveniently evaluated in this way. A detailed description of the observed Mn I and Mn II spectra is given for Ar, Ar–H2 and Ne plasmas and relevant excitation/ionization mechanisms are discussed. Matrix effects in analysis of manganese by glow discharge spectroscopy are discussed. A list of important Mn I and Mn II lines excited in the glow discharge plasma is given.

Low temperature plasma surface alloying and characterisation of a superduplex stainless steel

AbstractBecause of their superior mechanical properties and high corrosion resistance in aqueous environments, duplex stainless steels are the material of choice for equipment used in the off-shore gas and oil industry. However, wear in chloride containing water (i.e. corrosion wear) is considered as a major concern. During the past decade, a new low temperature plasma surface alloying technique has been developed to achieve combined improvements in hardness, wear resistance and fatigue properties of austenitic stainless steels, without impairing their corrosion behaviour due to the formation of S-phase. However, few researchers have applied this technique to duplex stainless steel (DSS) and no work has been reported for super DSS (SDSS). In this paper, SDSS 2507 has been DC plasma nitrided under a range of treatment conditions. Energy dispersive X-ray spectroscopy (EDX), Glow discharge Spectrometry (GDS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterise the microst...

Electrochemical hydriding performance of Mg–TM–Mm (TM=transition metals, Mm=mischmetal) alloys for hydrogen storage

Eighteen as-cast binary Mg–Ni, Mg–Mm and ternary Mg–Ni–Mm and Mg–Ni–TM (TM=transition metals (Cu, Zn, Mn and Co); Mm = mischmetal containing Ce, La, Nd and Pr) alloys were hydrided by an electrochemical process to determine the alloys with the most potential for electrochemical hydrogen storage. The alloys were hydrided in a 6 mol/L KOH solution at 80 °C for 480 min and at 100 A/m2. To assess the electrochemical hydriding performance of alloys, maximum hydrogen concentrations, hydrogen penetration depths and total mass of absorbed hydrogen in the alloys were measured by glow discharge spectrometry. In addition, the structures and phase compositions of the alloys both before and after hydriding were studied by optical and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. It was determined that the highest total amount of hydrogen was absorbed by the Mg–25Ni–12Mm and Mg–26Ni (mass fraction, %) alloys. The maximum hydrogen concentrations in the Mg–25Ni–12Mm and Mg–26Ni alloys were 1.0% and 1.6%, respectively. The main hydriding product was the binary MgH2 hydride, and the ternary Mg2NiH4 hydride was also detected in the Mg–25Ni–12Mm alloy. The electrochemical hydriding parameters achieved are discussed in relation to the structures of alloys, alloying elements and hydriding mechanisms.

Structural and corrosion characterization of biodegradable Mg–RE (RE=Gd, Y, Nd) alloys

Binary Mg–Gd (up to 5% Gd in mass fraction), Mg–Nd (up to 9% Nd in mass fraction) and ternary Mg–Gd-Y (up to 5% Gd, 1% Y) alloys with precisely determined contents of cathodic impurities (Fe, Ni, Cu, Co) were studied. The alloys were studied in the as-cast state (cooling rate of 500 K/min) and after solution heat treatment (T4). Structures were investigated by optical and scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and glow discharge spectrometry. Structural investigation was completed by Vickers hardness measurements. Corrosion behavior in the simulated physiological solution (9 g/L NaCl) was assessed by immersion tests and potentiodynamic measurements. It was found that the structures of the as-cast alloys were dominated by fine α-Mg dendrites and eutectic Mg–RE phases. The dendrites exhibited RE-concentration gradients which were most pronounced in the Mg–Gd alloys. For this reason, the T4 heat treatment of the Mg–Gd alloy led to the formation of a new cuboidal Mg5Gd phase. The corrosion resistance was significantly improved by Gd. The effect of Nd was weak and the addition of Y to Mg–Gd alloys had harmful effect on the corrosion resistance. The T4 heat treatment strongly accelerated the corrosion of Mg–Gd alloys. Its effect on the corrosion of Mg–Nd alloys was not significant. The observed corrosion behavior of the alloys was discussed in relation to their structural states and contents of cathodic impurities.

Structure, mechanical properties, corrosion behavior and cytotoxicity of biodegradable Mg–X (X = Sn, Ga, In) alloys

As-cast Mg–Sn, Mg–Ga and Mg–In alloys containing 1–7wt.% of alloying elements were studied in this work. Structural and chemical analysis of the alloys was performed by using light and scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction, x-ray photoelectron spectroscopy and glow discharge spectrometry. Mechanical properties were determined by Vickers hardness measurements and tensile testing. Corrosion behavior in a simulated physiological solution (9g/l NaCl) was studied by immersion tests and potentiodynamic measurements. The cytotoxicity effect of the alloys on human osteosarcoma cells (U-2 OS) was determined by an indirect contact assay. Structural investigation revealed the dendritic morphology of the as-cast alloys with the presence of secondary eutectic phases in the Mg–Sn and Mg–Ga alloys. All the alloying elements showed hardening and strengthening effects on magnesium. This effect was the most pronounced in the case of Ga. All the alloying elements at low concentrations of approximately 1wt.% were also shown to positively affect the corrosion resistance of Mg. But at higher concentrations of Ga and Sn the corrosion resistance worsened due to galvanic effects of secondary phases. Cytotoxicity tests indicated that Ga had the lowest toxicity, followed by Sn. The most severe toxicity was observed in the case of In.

Enhancement of Ti-containing hydrogenated carbon (Ti[sbnd]C:H) films by high-power plasma-sputtering

Ti-containing amorphous hydrogenated carbon (TiC:H) thin films were deposited on stainless steel SS304 substrates by high-power pulsed magnetron sputtering (HPPMS) in an atmosphere of mixed Ar and C2H2 gases using titanium metal as the cathodic material. The multilayer structure of the deposited film had a TiTiCDLC gradient to improve adhesion and reduce residual stress. This study investigates the effects of substrate bias and target-to-substrate distance on the mechanical properties of TiC:H films. Film properties, including composition, morphology, microstructure, mechanical, and tribology, were examined by glow discharge spectroscopy (GDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and a nanoindenter and a pin-on-disk tribometer. Experiments revealed impressive results.

Regularities of application of glow discharge spectrometry for quantitative layer-by-layer analysis of thin coatings

Regularities of application of glow discharge spectrometry are considered for quantitative layer-by-layer analysis of thin coatings on steels. The known methods of surface analysis used in industry and in research are compared. The main fields of application of glow discharge spectrometry are considered. The key causes for distortion of the analytical signal shape in quantitative layer-by-layer analysis using glow discharge spectrometers are discussed: the effect of the etching pit shape, analytical noise, and regularities of surface geometry of the studied samples. The main limitations of the methods in analysis of thin layers and coatings are shown. Calibration samples are developed for control of the thickness of thin chromium electrochemical coatings on steels. Metrological characteristics are estimated in measurement of the coating thickness. A method of quantitative layer-by-layer analysis on SA-2000 and GDS 850A glow discharge spectrometers (LECO) is proposed.

Effect of the Duty Cycle on Boronized Layer Formed by Pulse Electrodeposition

Boronized layer on silicon steel substrate was fabricated using pulse electrodeposition technique with different duty cycle in KCl-NaCl-NaF-Na2B4O7 molten salts. The effect of the duty cycle on composition and microstructure of obtained layer was investigated. The boronized layer was analyzed by X-ray diffraction analysis (XRD), optical microscopy (OM), glow discharge spectrometry (GDS), and atomic force microscopy (AFM). The results showed that in the range of 10-50%, duty cycle almost had no effect on composition and thickness of the layer. The boronized layers in this range exhibited FeB phase on the surface of silicon steel. However, duty cycle had great effect on the microstructure of the boronized layer. A fine grain size boronized layer can be obtained at a duty cycle of 20%.

Mutual electrosurface transfer and phase formation at the MeWO4|WO3 (Me = Ca, Sr, Ba) interface: Electron microscopy data

Experiments on solid-phase electrosurface migration through formally inert eutectic WO3|MeWO4 interfaces in symmetric electrochemical cells such as Pt|WO3|MeWO4|WO3|Pt are performed. It is shown that the most significant changes occur at the “cathode” interface (−)Pt|WO3|MeWO4|, where counter electrosurface drawing of WO3 to the inner surface of MeWO4 ceramics (with the formation of two-phase distributed composite WO3|MeWO4) and a much smaller flow of Me2+ components to the WO3 ceramics depth are observed. Scanning and transmission electron microscopy showed the formation of nano- and microscale objects of various shape in grain boundaries’ regions, among which well-faceted nanoobjects shaped as ribbons and rods from a few to hundreds of nanometers thick are noticeable. The Ca and Sr contents in WO3(−) cathode pellets after experiments in cells are determined by X-ray fluorescence analysis, scanning electron microscopy, energy-dispersive analysis, and depth profiling using glow-discharge spectrometry. The data obtained are interpreted based on the concepts of solid-phase electrocapillarity (WO3 migration) and electrochemical intercalation of Me into the WO3 structure.

Microvoid Formation at Solder–Copper Interfaces During Annealing: a Systematic Study of the Root Cause

The electrodeposition conditions that contribute to microvoid formation during isothermal aging of Pb-free solder-electrodeposited copper were evaluated in a systematic series of processing experiments. The results of 2K full-factorial design of experiment are presented to show the effect of prescreened electroplating parameters such as brighteners, wetting agent, bath age, and current density on the propensity for microvoiding at solder–copper interfaces after annealing at 125°C for 40 days. It was found that the amount of microvoiding is greatly affected by bath age, wetting agent, brightener, and their interactions. Time-of-flight secondary-ion mass spectroscopy and glow discharge spectroscopy allowed us to establish a correlation between impurities incorporated in copper during electroplating and microvoiding at the solder–copper interface.

Coloration and Depth Distribution of Cations Electrochemically-inserted into Electrochromic WO3 Thin Films

Li+ and H+ ions were electrochemically inserted into amorphous WO3 films prepared on an ITO-coated glass substrate by an R.F. magnetron sputtering method under Ar/O2 flow ratios of 4/1 (SP1)and 1/1 (SP2). The cation distribution was estimated indirectly by depth profiles of refractive-index obtained from prism coupler measurements and was evaluated directly by glow discharge spectrometry (GDS). H+ ions inserted were segregated only at deeper region around ITO electrode, which was independent to the preparing condition. In the case of Li+ insertion into SP1 film, Li+ ions were initially segregated at around ITO electrode, and after further insertions, they were also distributed at around the surface of WO3 film. In SP1 film, Li+ ions at around ITO electrode seemed to contribute to coloration. In SP2 film, however, Li+ ions subsequently inserted, which were uniformly distributed in the film, were only involved in coloration. The difference in depth distribution and coloration was due to the difference in atomic structure of WO3 films.

Effect of Current Density on Composition and Microstructure of Boronized Layer by Electrodeposition

Boronized layer was prepared on silicon steel substrate by pulse electrodeposition in KCl-NaCl-NaF-Na2B4O7 molten salts with different current density. The effect of current density on composition and microstructure of boronized layer was studied. The phase, the cross-sectional morphology and the compositional depth profile of the layer were studied by X-ray diffraction analysis (XRD), optical microscopy (OM) and glow discharge spectrometry (GDS). The presence of FeB on the surface of the boronizied steel was confirmed by XRD analysis. Cross sectional observation revealed that the boronized layer consisted of the outer layer FeB and the sublayer Fe2B. In addition, the low current density produced more proportion of Fe2B and bigger saw-tooth grains.

Influence of Pulse Electrodeposition Parameters on Thickness of Boronized Layer by Orthogonal Test

Boronized layer was prepared on carbon steel substrate by pulse electrodeposition in KCl-NaCl-NaF-Na2B4O7 molten salts. The orthogonal experimental design was used to study the influence of pulse electrodeposition parameters on the thickness of boronized layer. The distribution of boron content of the boronized layer was measured using the glow discharge spectrometry (GDS) and the depth from the surface to the inflection point was taken as the layer thickness. It was found that the order of significant factors for the thickness is electrodeposition temperature > electrodeposition time > current density > borax content > duty cycle. Based on the results of the range analysis, the maximum thickness was found at a current density of 120mA/cm2, a electrodeposition temperature of 900°C, a electrodeposition time of 120 min, a duty cycle of 10%, and a borax content of 0.04 mole ratio.

활성 스크린 이온질화 처리된 마르텐사이트계 스테인리스 431강의 기계적 특성

Martensitic stainless steel STS 431 has been nitrided by active screen ion nitriding under the various temperature and time. The thickness of diffusion layer, case depth, hardness and composition phases were investigated using field emission scanning electron microscopy (FE-SEM), micro-Vickers hardness tester, X-ray diffraction (XRD) and glow discharge spectroscopy (GDS). It was observed that the thickness of diffusion layer depends strongly on the treatment temperature and time. A sample, which was nitrided at <TEX>$450^{\circ}C$</TEX> for 8hours, was a maximum hardness of Hv0.01 1558 and nitride layer of <TEX>$70{\mu}m$</TEX>. As shown in XRD patterns, <TEX>$\varepsilon(Fe_{2-3}N)$</TEX> and expanded martensite (<TEX>${\alpha}_N$</TEX>) phases which was saturated with nitrogen solid solution were in the nitrided layer treated at <TEX>$450^{\circ}C$</TEX> for 2 hours. Composition phases of <TEX>$\varepsilon$</TEX> <TEX>$(Fe_{2-3}N)$</TEX> and <TEX>${\gamma}'$</TEX> (<TEX>$Fe_4N$</TEX>) were observed after active screen nitriding at <TEX>$450^{\circ}C$</TEX> for 8 hours.

흑색 코발트 태양 선택흡수막의 광학적특성과 구조

Black cobalt solar selective coatings were prepared by thermal oxidation of electroplated cobalt metal on copper and nickel substrates. The optical properties and structure of the black cobalt selective coating for solar energy utilizations were characterized by glow discharge spectrometry (GDS), ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer, atom force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). The optical properties of optimum black cobalt selective coating prepared on copper substrate were a solar absorptance of 0.82 and a thermal emittance of 0.01. From the GDS depth profile analysis of these coatings, the concentration of cobalt particles near the interface was higher than at the surface, but oxygen concentration at the surface was higher than at the interface. These results suggest that the selective absorption was dominated by this chemical composition variation in the coating. The surface of this film exhibited morphology with root-mean-square(rms) roughness of about 144.3nm. XPS measurements data showed that several phases of Co coexist(,CoO) in the film.

Effects of bias on properties of Ti–C:H films coated by filtered cathodic vacuum arc

A bias voltage apparatus is attached to the filtered cathode vacuum arc system for coating a diamond-like film containing Ti on WC substrate. Ti, which acts as the cathode target, is sputtered by plasma, and reacts with C2H2 gas, then deposits on the WC under working conditions of 60 A current and voltage between −50 and −275 V. Such processed diamond-like film containing Ti(Ti–C:H) is analysed by glow discharge spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and nanoindentation for determining Ti concentration, crystallographic structure, bonding mode and mechanical properties. Characteristic parameters are determined to obtain suitable properties, and the underlying reasons are also addressed.

Nanostructured Ti-Cr-B-N and Ti-Cr-Si-C-N coatings for hard-alloy cutting tools

Nanostructured Ti-Cr-B-N and Ti-Cr-Si-C-N coatings with various contents of chromium and nitrogen are obtained by the magnetron sputtering of multiphase composite targets. Their structure and phase composition are investigated by X-ray phase analysis, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and optical emission glow-discharge spectroscopy. The Ti-Cr-B-N and Ti-Cr-Si-C-N coatings are based on the fcc phase with texture (100) and crystallite size <25 nm. The Si3N4-based hexagonal phase was also revealed in the Ti-Cr-Si-C-N coatings. An investigation into the properties of coatings with the use of methods of nanoindentation, scratch testing, and by performing tribological tests showed that they have a hardness of up to 30 GPa, an adhesion strength no lower than 35 N, and their friction coefficient falls in the range of 0.35–0.57. Coatings also possess high thermal stability, resistance to oxidation, and corrosion stability in a 1N H2SO4 solution. The data obtained in tests of hard-alloy cutting tools indicate that the deposition of nanostructured Ti-Cr-B-N and Ti-Cr-Si-C-N coatings increases its resistance by a factor of 11–17.

Characterization of Doped Amorphous Silicon Thin Films through the Investigation of Dopant Elements by Glow Discharge Spectrometry: A Correlation of Conductivity and Bandgap Energy Measurements

The determination of optical parameters, such as absorption and extinction coefficients, refractive index and the bandgap energy, is crucial to understand the behavior and final efficiency of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The influence of small variations of the gas flow rates used for the preparation of the p-a-SiC:H layer on the bandgap energy, as well as on the dopant elements concentration, thickness and conductivity of the p-layer, is investigated in this work using several complementary techniques. UV-NIR spectrophotometry and ellipsometry were used for the determination of bandgap energies of four p-a-SiC:H thin films, prepared by using different B2H6 and SiH4 fluxes (B2H6 from 12 sccm to 20 sccm and SiH4 from 6 sccm to 10 sccm). Moreover, radiofrequency glow discharge optical emission spectrometry technique was used for depth profiling characterization of p-a-SiC:H thin films and valuable information about dopant elements concentration and distribution throughout the coating was found. Finally, a direct relationship between the conductivity of p-a-SiC:H thin films and the dopant elements concentration, particularly boron and carbon, was observed for the four selected samples.

Study of the diffusion kinetics and mechanism of electrochemical hydriding of Mg–Ni–Mm alloys

Electrochemical hydriding in a 6 M KOH solution at 20 and 80 °C for 480 min was applied on a series of as-cast binary Mg–Ni and ternary Mg–Ni–Mm alloys (Mm = mischmetal containing 45% Ce, 38% La, 12% Nd and 4% Pr) containing 11–24 wt. % Ni and 0–6 wt. % Mm. The kinetics and mechanism of the hydriding process, as well as hydrogen release temperatures, were studied by glow discharge spectrometry hydrogen profiling, scanning electron microscopy, energy dispersion analysis, X-ray diffraction and mass spectrometry. A maximum hydrogen concentration of 1.1% was achieved in the eutectic MgNi24Mm5 alloy hydrided at 80 °C. In all cases, the main hydriding product was binary MgH 2 hydride. Mass spectrometry revealed its destabilization due to Ni and Mm because its decomposition temperature was lowered by about 100 °C. Both nickel and mischmetal showed positive effects on hydriding and dehydriding kinetics. These effects are discussed in relation to the hydriding mechanism, electronic structure and atomic size of additives and structural variations of the alloys. Based on the H-concentration profiles, the diffusion coefficients of hydrogen were estimated. For the eutectic MgNi24Mm5 alloy, the H diffusion coefficient at 20 °C was 4 · 10 −10 cm 2 s −1.

Growth Kinetics and Microstructure of Siliconized Layer by Molten Salt Electrodeposition

The siliconized layers were formed on the surface of hot rolled grain oriented silicon steel using a molten salt pulse electrodeposition method. The process was performed in the temperature range 1023-1123 K and with varying deposition time (60-180 min). The profile distribution of Si in the siliconized layer was measured using the glow discharge spectrometry (GDS) and the depth from the surface to the substrate was taken as the layer thickness. The morphology and structure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that a longer deposition time tended to produce a larger grain and a looser, rougher layer. The phase structure of the layer was composed of Fe3Si with (110) preferred orientation in the experimental range. The longer deposition time resulted in an increase in thickness layer and the thickness of the layers ranged from 17 to 165m. Kinetic studies showed that the siliconized layer grew with a parabolic rate law, indicating the diffusion controlled growth. The activation energy for growth of siliconized layer was about 242 kJ/mol.