Tetsu-to-Hagané
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ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 93 (2007), No. 2

  • Preface to the Special Issue “Recent Developments in Analytical Technology and Methodology”

    pp. 71-71

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    DOI:10.2355/tetsutohagane.93.71

  • Chemical Analysis of Iron and Steels Using Flow Injection Analysis (FIA) System

    pp. 72-79

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    DOI:10.2355/tetsutohagane.93.72

    We present a review on flow injection analysis (FIA) system for the chemical analysis of iron and steel samples. This review begins with explanation of brief history of FIA. Next, precise determination methods for major components are presented. Methods for the determination of minor to trace components are classified with its methodology for separation of analytes from matrix are discussed, followed by the discussions of standard, non-separation method and the on-line electro-dissolution of samples. Finally, the review concludes with a brief examination of the near-term areas of research and development in FIA systems.
  • Determination of Trace Lead in Iron and Steel by Electrothermal Atomic Absorption Spectrometry after Coprecipitation with Yttrium Phosphate

    pp. 80-84

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    DOI:10.2355/tetsutohagane.93.80

    The coprecipitation technique using yttrium phosphate as a coprecipitant has been applied to separation of lead from iron matrix. Lead ranging from 0.035 to 1.0 μg could be coprecipitated quantitatively with yttrium phosphate at pH 3.0 from 100 mL of approximately 1 mol/L nitric acid solution containing up to 500 mg of iron and 3.0 g of ascorbic acid as a reducing agent; the recovery of iron could be suppressed at less than 0.1%. The collected lead could be determined by electrothermal atomic absorption spectrometry without any interference of yttrium and phosphate after dissolution of the precipitate. In the proposed method, the limits of detection (3σ) and quantification (10σ), which were calculated based on the values obtained from the eight replicate determinations of the blank, were 0.010 μg and 0.035 μg, respectively. The proposed method was applicable to the determination of lead in certified reference material (JSS 591-1) and commercially available iron powder.
  • Separation of Trace Metals from an Iron Matrix with Emulsion Globules for Inductively Coupled Plasma-Mass Spectrometry

    pp. 85-88

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    DOI:10.2355/tetsutohagane.93.85

    A water-in-oil type emulsion containing 7-dodecenyl-8-quinolinol (Kelex-100) was prepared from 1.0 mol dm-3 HCl and a (1+2) mixture of toluene and n-heptane using sorbitan monooleate (Span-80) as an emusifier. The resulting emulsion was gradually injected into the sample solution and dispersed by stirring for 10 min as numerous tiny globules. When an iron(III) matrix was converted into the colloidal hydroxides by adjusting the sample pH to 3.5, traces of Ti(IV), Cu(II), Ga(III), In(III), and Bi(III) were selectively transported into the internal aqueous phase of the emulsion, leaving the iron matrix in the sample solution. After collecting the dispersed emulsion globules, they were demulsified and the metals in the segregated aqueous phase were determined by inductively coupled plasma-mass spectrometry. The detection limits (in μg g-1) were 0.05 for Ti, 0.08 for Cu, 0.02 for Ga, 0.01 for In, and 0.02 for Bi. The proposed method was successfully applied to the analysis of high-purity iron.
  • Determination of Trace Metals in Steel by Combining Anion Exchange Separation with ICP-AES

    pp. 89-93

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    DOI:10.2355/tetsutohagane.93.89

    A selective anion-exchange separation in potassium iodide-hydrochloric acid media has been combined with ICP-AES for the determination of trace metals in steel. An appropriate amount of steel sample was decomposed with a mixture of nitric acid, hydrochloric acid and hydrogen peroxide, or a mixture of nitric acid, hydrochloric acid and sulfuric acid, and prepared as a potassium iodide-hydrochloric acid solution containing ascorbic acid to reduce iron(III) to iron(II). The sample solution was passed through a strongly basic anion exchange resin column to remove iron. The trace metals adsorbed on the column were simultaneously eluted with a dilute nitric acid solution and determined by ICP-AES. The proposed method was successfully applied to the determination of Bi, Te, Cu, Pb and Sb at ppm levels in steel reference materials provided by Japan Iron and Steel Federation, and National Institute of Standards and Technology, yielding reasonable results with regard to accuracy and reproducibility.
  • Determination of Trace Amounts of Bismuth in Iron and Steel by Pre-column Derivatization Reversed-phase High-performance Liquid Chromatography with Ethylenediaminetetraacetate

    pp. 94-99

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    DOI:10.2355/tetsutohagane.93.94

    Determination of trace amounts of bismuth in steel and iron was demonstrated with high performance liquid chromatography using ethylene-diaminetetraacetate (EDTA) as a pre-column derivatizing reagent. Standard materials of steel and iron were decomposed with a mixture of nitric acid and hydrochloric acid, followed by subjected to sulfuric fuming. The residues were dissolved with 0.1 mol dm-3 hydrochloric acid to prepare digested sample solutions. Bismuth ions in the digested solution were separated from iron matrix with an anion exchange column under 0.1 mol dm-3 hydrochloric acid. The adsorbed bismuth ions on the anion exchange column could be recovered with 0.1 mol dm-3 nitric acid, quantitatively. After the recovered bismuth ions were derivatized with EDTA under pH 3.0, HPLC separation of the bismuth-EDTA complex was performed with an ODS column using an aqueous solution containing 0.01 mol dm-3 monochloroacetate buffer (pH 3.0) and 2.0×10-3 mol kg-1 of tetrabutylammonium bromide was monitored at 265 nm spectrophotometrically. A linear calibration was observed in the concentration range from 1×10-8 to 1×10-6 mol dm-3 of bismuth. The detection limit (3σ) of Bismuth was 8.8×10-8 mol dm-3, which corresponded to 0.92 ppm in iron and steel samples. An analytical recovery of a steel sample obtained with the HPLC method agreed with that obtained with GD-MS. The recoveries of bismuth added to the digested solution of iron and steel were with in 99.5 to 118%, indicating potential of the HPLC method for iron and steel analyses.
  • Rapid Determination of Phosphorus in Steel by Electrolytic Gas Introduction—ICP-AES Method

    pp. 100-104

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    DOI:10.2355/tetsutohagane.93.100

    Solid steel sample dissolution with electrolysis-inductively coupled plasma atomic emission spectrometry (ICP-AES) is applicable to multi-elemental analysis of steel by analyzing the elements in the electrolyte. The disk-shaped steel sample is electrolyzed through an electrolysis cell and the electrolyte is introduced into the ICP continuously. However, the sensitivity of phosphorous was not enough practically.
    We examined to improve the sensitivity with sample heating and electrolytic gas introduction system. At room temperature, phosphorus exists as PO43- ion in the electrolyte, and sensitivity was not enough due to the low efficiency in sample introduction efficiency to the plasma via nebulizer. However when the sample was heated, gaseous PH3 improved introduction efficiency therefore sensitivity was improved remarkably. When the steel samples taken from steel making process, heated at 80°C, were analyzed with the technique in which generated gas in the electrolysis was introduced to the plasma, the analytical results were in a good agreement with these of the result of the phosphovanadomolybdate spectrophotometric method.
  • Quantitative Analysis of Ca-rich Oxide Inclusions in Steel by Galvanostatic Electrolysis

    pp. 105-110

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    DOI:10.2355/tetsutohagane.93.105

    It is well known that oxide inclusions, such as aluminum oxide or Ca-rich oxide, sometimes cause serious problems for steel products. Usually, oxide inclusions have been measured by the extraction method or by optical microscope observation prescribed by JIS and ASTM, but the quantity of inclusions in steel products are now below the detection limits of these conventional methods. Recently several new methods were developed to evaluate inclusions both in size and in amount; for example, electron beam melting method coupled with optical microscopic analysis and photo scattering method coupled with acid extraction. However, it is difficult to evaluate Ca-rich oxide inclusions in amount even though by using above mentioned new methods. The reason is as follows:
    (1) It is difficult to extract Ca-rich oxide inclusion quantitatively from steel.
    (2) The quantity of Ca-rich oxide inclusions in steel is quite low.
    The authors developed a new method to extract ca-rich oxide inclusions in steel quantitatively, which method is based on galvanostatic electrolysis with non- aqueous electrolyte.
    The composition of new type of electrolyte is 40% maleic anhydride-3% tetrametylammonium chloride-methanol.
    100 gram of steel matrix can be electrolyzed with 1 liter of the new electrolyte.
    This technique makes it possible to determine Ca-rich oxide inclusions quantitatively.
  • Determination of Trace Elements in Certified Iron and Steel Standard Materials by Instrumental Neutron Activation Analysis

    pp. 111-115

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    DOI:10.2355/tetsutohagane.93.111

    Trace elements in certified iron and steel reference standard materials of NIST, SRM1763 and SRM1765 were determined by an instrumental neutron activation analysis (INAA). Three aliquot samples of each certified standard reference material (ca. 85-210 mg) were irradiated for 6 h at thermal power of 100 kW (thermal neutron flux of 4.3×1014 n m-2s-1) and at thermal power 3.5 MW (thermal neutron flux of 5.3×1017 n cm-2s-1) in JRR-4 (Japan Atomic energy Agency). The irradiated samples were measured by γ-ray spectrometry using a coaxial Ge detector. The concentration of 11 elements (Al, Ti, V, Cr, Mn, Co, Ni, Cu, As, Mo, Sb) in the SRM1763 and 9 elements in the SRM1765 were determined by INAA. The determined values were in good or nearly good agreement with the certified values and reference value.
  • Helium Microwave Plasma Atomic Emission Spectrometry at Atmospheric Pressure for Nonmetal Element Analysis

    pp. 116-120

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    DOI:10.2355/tetsutohagane.93.116

    The accurate determination of trace elements in steel is an important and challenging task in analytical chemistry. The variation of the contents of nonmetal elements such as C, P and S in steel can have a significant influence on the mechanical and physical properties. A sensitive and accurate method for the determination of these elements in steels is therefore required.
    The aim of the present work is to develop an accurate method using He-MIP AES (Helium Microwave-Induced Plasma Atomic Emission Spectrometry) to determine the trace amounts of these elements in the gas, liquid and solid samples. The optimization of the He-MIP AES technique and its analytical figures of merit, as well as its application to the determination of these elements in the samples, were described. The samples were transported and excited in a microwave induced helium plasma operated at atmospheric pressure.
    A high-power (∼1000 watt CW, 2.45 GHz) annular-shaped microwave-induced helium plasma (He-MIP) was developed for the determination of nonmetals in the aqueous solutions, and the characteristics were presented. The plasma was generated at atmospheric pressure by an Okamoto cavity of the surface wave mode. No external cooling was used to stabilize the plasma. The electron density and iron-excitation temperature were on the order of 1014/cm3 and 6500K, respectively. An air for gas sample was aspirated with an aspirator and introduced directly into the He-MIP. Carbon (247.9 nm) in the air was detected. An aqueous solution was injected into the plasma by an ultrasonic system with desolvation and condensation. Introduction of aqueous fluoride in the form of NaF, chloride in the form of NaCl and bromide in the form of KBr produced intense emission and detection limits of 100 ppb for FI (685.6 nm), Cl II (479.5 nm) and 150 ppb for Br II (470.5 nm) were obtained. Detection limits of the carbon and phosphorous in the aqueous solution were 1 ppb and 2 ppb, respectively.
  • Emission Characteristics of Okamoto-cavity Microwave-induced Plasma Using Nitrogen-Argon Mixed Plasma Gas

    pp. 121-127

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    DOI:10.2355/tetsutohagane.93.121

    An Okamoto-cavity microwave-induced plasma (MIP) with nitrogen-argon mixed gas was investigated to employ an alternative excitation source instead of the conventional nitrogen plasma. The emission intensities of atomic emission lines of copper and iron having small excitation energy were clearly elevated by adding argon gas to the nitrogen plasma, giving the maximum intensity at the argon mixing ratio of 40%. On the other hand, the excitation temperature, which was estimated from Boltzmann plots using Fe I emission lines ranging from 358 to 380 nm, was hardly changed when the amount of argon increased up to 50%. Also, the ionic-to-atomic intensity ratios of calcium, magnesium, and yttrium were not changed so much by mixing the argon gas. These results concerning the excitation temperatue as well as the ionic-to-atomic ratio imply that the excitation characteristics of the N2-Ar MIP are similar to those of the N2 MIP. However, it was observed that the emitting zone of the N2-Ar MIP could be expanded compared to the N2 MIP. Energetic argon species, which are produced through collisions with electrons and nitrogen species, can expand the plasma region due to their smaller cross-section compared to nitrogen molecule species, and then can take part in excitation collisions of analyte atoms at the outer zone of the plasma, leading the increased emission intensities of the analyte atoms.
  • Determination of Oxygen in Magnesium by Glow Discharge Mass Spectrometry

    pp. 128-131

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    DOI:10.2355/tetsutohagane.93.128

    In the present experiments, preferable results were obtained by applying glow discharge mass spectrometry (GD-MS) for quantitative analysis of oxygen in magnesium. The relative sensitivity factor (RSF) method was applied for measurements, since there was no standard material for magnesium analysis. Removal of the surface oxygen contaminants was investigated before the Mg specimen measurements. It was clarified that 5000 s of pre-discharge period was required to remove surface oxygen for both of pin shape and disk shape samples. As a result, the oxygen contents of the pure Mg and re-dissolved Mg were obtained as 9 ppm and 26 ppm, respectively. In order to check the results obtained by GD-MS measurements, charged particle activation analysis was also applied for the same specimens. The oxygen contents of the pure Mg and re-dissolved Mg were obtained as 12 ppm and 26 ppm, respectively with this method. On the basis of the results, GD-MS is possible technique for oxygen analysis in Mg and its alloys with high sensitivity.
  • Chemical State Analysis of Fine Particles using XAFS

    pp. 132-137

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    DOI:10.2355/tetsutohagane.93.132

    The measurement of X-ray absorption fine structure (XAFS) spectra of fine particle samples using the total electron yield and X-ray fluorescence yield methods reveals the chemical state of surface and bulk, separately, of powder samples. For various particulate environmental samples (both standard samples and sampled in the fields) are measured and the chemical state analysis of sulphur has been performed in the present study. The difference among the samples collected at a same place/date and the similarity among the samples collected at the different places/date are discussed from the view point of the error introduced in the present experiment.
  • In-situ Observation of Microstructure Formation Process of Weld Metals by Time-resolved X-ray Diffraction

    pp. 138-144

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    DOI:10.2355/tetsutohagane.93.138

    In-situ characterization of directional solidification process during welding was carried out using utilizing intense synchrotron radiation. Then, behaviors of dendrites in steels during welding of a practical manufacturing process were investigated using time-resolved X-ray diffraction with the uniquely-sensitive two-dimensional pixel detector. Consequently, the crystal growth during rapid cooling was caught in detail by a systematic peak profile analysis in order to acquire the essential information for controlling the weld microstructure. Our results would suggest the possibility of rotation of dendrites in high alloys and fraction of maximum of shrinkage is corresponded to thermal expand coefficient of low alloy in directional solidification during rapid cooling.
  • Quantitative Composition Analysis of Spherical Cementite by Three-dimensional Atom Probe

    pp. 145-149

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    DOI:10.2355/tetsutohagane.93.145

    To examine the quantitative performance of three-dimensional atom probe (3D-AP) in steel materials, composition analysis of spherical cementite (Fe3C) formed in an annealed pearlitic steel wire was conducted. It was visualized in three dimensions that manganese and chromium atoms were concentrated in cementite, while silicon atoms were concentrated in ferrite. Phosphor atoms were segregated at the cementite-ferrite interface. By taking all carbon molecular ions into consideration, the carbon concentration in cementite was in the range of 25-27 at%, which approximately coincided with the stoichiometric composition of 25 at%. On the other hand, the iron concentration in cementite was in the range of 70-73 at%, which was a few atomic % lower than 75 at%. The reduction of the iron concentration is caused by the substitution of manganese, chromium and silicon atoms for iron atoms in cementite. It was shown that the 3D-AP enables the quantitative composition analysis with high accuracy. Inhomogeneous distribution of manganese and chromium in cementite was observed, and it was explained by the change in the partition coefficient depending on the interface mobility of spherical cementite growth.
  • The Application of Infrared Spectrophotometry to Analysis of Dehydration Processes of Inorganic Hydroxides and Evaluation of Monolithic Refractories

    pp. 150-155

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    DOI:10.2355/tetsutohagane.93.150

    Inorganic oxides are widely used as raw materials and formed as byproducts in iron and steelmaking processes. Some inorganic oxides such as CaO and MgO absorb water to form inorganic hydrates. When hydrates form, they expand. On the other hand, hydrates often dehydrate on heating to form oxides. To analyze hydrates in oxides is therefore important in order to examine hydration and dehydration processes.
    This paper concerns with the analysis of dehydration processes of Mg(OH)2, Ca(OH)2 and Al(OH)3 in which high temperature infrared spectrophotometry and thermogravimetry (TG) were used to elucidate the expansion behavior of monolithic refractories. Two monolithic refractories, which contained the same amount of MgO, were investigated with hydration. Mg(OH)2 was observed in the samples that expanded after pressed. No Mg(OH)2 was observed in the sample that did not expand after pressed. In addition, infrared spectrums give the amount of Mg(OH)2. Infrared spectrophotometry can be used for the quantitative analysis of the small amount of inorganic hydrates in oxides.
  • In-situ Surface Observation of Zn and Zn-5%Al Alloy in Aqueous Solution by Polarization Modified Infrared Reflection Absorption Spectrometry

    pp. 156-162

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    DOI:10.2355/tetsutohagane.93.156

    The metal/liquid interface of Zn and Zn-5% Al alloy in aqueous solution has been investigated by means of polarization modified infrared reflection absorption spectrometry (PM-IR-RAS) as an in-situ surface observation technique. The experimental set up consists of an in-situ cell in which the aqueous solution is introduced and an optical system for PM-IR-RAS, which is designed so that spectra can be obtained during exposure of the metal sample to aqueous solution in an in-situ cell.
    It was found that surface OH at/or near Zn and Zn-5% Al alloy in aqueous solution was presented more than Pt. After immersion in water, a precipitated layer of Zn(OH)2 was detected on the surface of Zn-5% Al alloy coating, but it was not detected on Zn. Aluminum in Zn coating would prevent Zn(OH)2 from changing into ZnO.
  • Visualization of Fine Precipitates TiN in Low-alloy Steel by Using Energy-filtered Transmission Electron Microscopy

    pp. 163-168

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    DOI:10.2355/tetsutohagane.93.163

    In this paper, advantage and measurement principle of energy-filtered transmission electron microscopy (EF-TEM), which can measure the elemental distribution on local area in a material, are outlined. The energy-filtering technique by EF-TEM is applied to the visualization of fine precipitates TiN in a low-alloy steel. Through the observations of the energy-filtered images of TiN using Ti-M edge in electron energy-loss spectra, TiN in α-Fe matrix is clearly observed. As a result, it is clarified that this technique is quite useful to evaluate the spatial distribution of TiN in the low-alloy steel. Furthermore, the advantage of the energy filtering technique using M edge for visualization of nano-precipitates containing transition metals such as titanium is discussed.
  • Application of Low-voltage Scanning Electron Microscopy to the Characterization of Steel Surface

    pp. 169-175

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    DOI:10.2355/tetsutohagane.93.169

    In this paper we will demonstrate how the use of low-voltage scanning electron microscopy (SEM) improves surface sensitivity and effective spatial resolution. The separation of chemical and morphological information can be possible when an SEM has two or more secondary electron (SE) detectors. A strong chemical contrast from a thin oxide layer on a steel sheet was obtained using a LEO 1530 with an on-axis annular in-lens SE detector by reducing the accelerating voltage down to 500 V. However, in using the E-T detector at the same accelerating voltage, the chemical contrast was weak and only the morphological information was visible. Secondary electron images obtained at various working distances confirmed that “separation” of secondary electrons occurred between the two SE detectors. Secondary electrons whose yield is sensitive to surface structure seem to be selectively detected by the in-lens detector. Consequently, surface sensitivity and a high resolution can be retained even at high accelerating voltages for secondary electron images obtained using the in-lens detector. Bulk contrast becomes dominant for secondary electron images obtained using the E-T detector, resulting in the degradation of spatial resolution at high voltages. The improvement in spatial resolution of backscattered electron images due to low electron penetration is clearly demonstrated for a complex oxide-sulfide inclusion.
  • Structural Analysis and Grouping of Inorganic Matter in Coal by 27Al NMR MQMAS Measurement

    pp. 176-181

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    DOI:10.2355/tetsutohagane.93.176

    Structural analysis of inorganic matter in coal is very important, from the viewpoint of both geology and coal utilization. However, it is often difficult to assign inorganic matter from common techniques such as XRD, because some inorganic matter, i.e. clay mineral, in coal has low crystallinity.
    On the other hand, solid-state NMR techniques are well suited for the analysis of noncrystalline solids such as inorganic matter in coal. Several kinds of minerals were estimated from the percentage of tetrahedral Al species that was determined by 27Al MAS NMR.
    In this study, we successfully developed the method for characterization of 4 minerals (kaolin, montmorillonite, muscovite, and alumina) in coal by virtue of the combination of a high magnetic field (16.4 T) and a MQMAS (Multiple Quantum Magic Angle Spinning) technique that is capable of cancel the second-order quadrupolar broadening. As a result, the structure of the inorganic matter in 26 natural coals was able to be identified. And 26 natural coals could be grouped into 6 groups according to 1-3 types of minerals combination.
  • Determination of Trace Carbon and Sulfur in Small Amounts of Iron and Steel by Use of a Tubular Furnace-combustion Infrared Absorption Analyzer

    pp. 182-186

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    DOI:10.2355/tetsutohagane.93.182

    As cultural or archeological iron and steel samples are valuable, those samples have to be analyzed with small amount, less than 0.5g. In order to determine carbon and sulfur in small amounts of iron and steel using a tubular furnace-combustion infrared absorption analyzer, the analytical method was investigated. The JSS certified standards were used as the iron and steel samples for an analysis, and these sample weight were used within the range of 0.05∼0.5 g. Also, a combustion improver was used tin or tin added to tungsten and measurement results were calibrated with only one kinds of JSS standards. The concentration (0.001∼5%) for carbon was determined with a combustion improver of tin and a calibration sample of JSS057-6 (C: 0.52%). The concentration (<0.001%) for carbon was determined with a combustion improver of tin and a calibration sample of JSS1203-2 (C: 0.0096%). The concentration (0.0001∼0.4%) for sulfur was determined with a combustion improver of tin added tungsten and a calibration samples of JSS242-10 (S: 0.03%). As the results, the concentrations of carbon and sulfur were obtained with good accuracy. But when determining trace carbon, the influence of the contamination on tungsten surface was occurred. It is necessary to determine trace carbon using only tin as the combustion improver.
  • Consideration of Highly-efficiency Ionization Using Helium Glow Discharge Ion Source

    pp. 187-189

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    DOI:10.2355/tetsutohagane.93.187

    High-effective ionization during ferrous analyses using a He glow-discharge ion source was investigated. The respective relationships between the ionization potential (Ip) of each element and various ionic strengths were studied in detail for He glow discharge and Ar glow discharge. The energies of the helium metastable atom (Hem) is 1910 kJ/mol (19.80 eV) and 2022 kJ/mol (20.96 eV). It is presumed that Hem contributes to creation of doubly-charged and singly-charged ions. Results show that numerous doubly-charged ions are generated by He glow discharge. If this ratio is greater than that of an internal standard element Fe, the RSF-value becomes greater than 1 (the ionic strength ratio decreases). Furthermore, with elements having Ip2 of more than approximately 18 eV, e.g., Ni, As, P, and C, the relative ionic strength of doubly-charged ion with respect to the singly-charged ion is only several percent at the highest. Consequently, the RSF-values approach unity (1). High-effective ionization by glow discharge is dependent upon the type of discharge gas, the matrix (internal standard element) and analyzing element, the presence of spectral interference, RSF-value, and other factors.
  • Effect of the Matrix Element on the Determination of Tramp Elements in Iron and Steel by ICP-OES: The Usefulness of the Matrix Removal

    pp. 190-194

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    DOI:10.2355/tetsutohagane.93.190

    On the determination of tramp elements (As, Bi, Cu, Pb, Sb, Sn, Zn) in iron and steel with inductively coupled plasma-optical emission spectrometry (ICP-OES), emission intensities of analytical atomic lines of these elements, background emission intensities, and degree of the spectral overlapping between the matrix and analyte elements were compared in the presence and the absence of an iron matrix. The presence of an iron matrix caused the gradual decrease in the emission intensities of the analytes and the increase in the background emission. Therefore sample weight must be controlled on chemical analysis. When the atomic lines of iron lay near to (or just on) the analytical atomic line, the line was not practically available. In order to overcome the problems described above, it was effective that the analytical elements were chemically separated from the iron matrix. By the chemical separation, the detection limits of tramp elements were drastically improved, e.g., from 1-10 ppm (μg g-1) levels to 0.01-0.1 ppm levels.
  • Monitoring of Generated Gas from Plastics during Pyrolysis in Hydrogen Atmosphere by FT-IR

    pp. 195-199

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    DOI:10.2355/tetsutohagane.93.195

    In order to characterize gas generation behavior of plastics during pyrolysis, a monitoring system using Fourier transform-infrared spectrometer (FT-IR) has been applied. This system can monitor simultaneously, continuously and simply the several kinds of gases, such as hydrocarbons, CO and CO2.
    Using this system, the influences of pyrolysis condition on gasification of plastics were investigated. The amount of gaseous components obtained from polyethylene(PE) and polypropylene(PP) heated in nitrogen gas were almost constant at 40wt%-carbon on changes of temperature (at 600 and 1000°C). In the case of pyrolysis in hydrogen gas, the amounts of gas from both plastics were increased to 100 wt%-carbon at 1000°C. On the other hand, the gasification ratio of polystyrene at 1000°C was only about 60 wt%-carbon even in hydrogen gas.
    Thus, the gas generation behavior from plastics on various conditions can be monitored by this system. It is thought that the gasification of (waste) plastics in actual processes such as a coke oven can be monitored by this system.

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