Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
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Volume 76, Issue 2
Displaying 1-8 of 8 articles from this issue
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Regular Articles
  • In-Situ Observation and Acoustic Emission Analysis for Corrosion Pitting of MgCl2 Droplet in SUS304 Stainless Steel
    Mitsuharu Shiwa, Hiroyuki Masuda, Hisashi Yamawaki, Kaita Ito, Manabu ...
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 122-128
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.122
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      Acoustic emission with near-field detection and optical video microscope monitoring was proposed to investigate the pitting corrosion caused by the small magnesium chloride droplet. For the corrosion testing of work-hardened SUS304 stainless steel, four types of the detected waveforms were characterized by the wavelet analysis. After the high activity AE signals, the corrosion product sheet was extended without or with low activity AE signals. With the cross-section observations, the detected AE signals were mainly attributed to the following three sources, the longitudinal and transverse cracking around the covered pitting, cracking of the oxidation products, and the early stage of the corrosion potential fluctuation.
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  • Degradation Process of Graphite Furnace Estimated from Atomic Gas Temperature of Iron in Graphite Furnace Atomic Absorption Spectrometry
    Tetsuya Ashino, Haruki Shimabukuro, Kazuaki Wagatsuma
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 129-133
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.129
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      GF-AAS has been employed for determining several trace impurities in metallic materials. The analytical precision in the continuous analysis tends to worsen due to thermal degradation of the graphite furnace at the atomization stage. Changes of the atomization condition along with increasing the number of measurements were investigated by monitoring the temporal variation in the atomic gas temperature of iron. In a working solution containing low-concentration of acid, the inner wall of the graphite furnace was gradually damaged and then the efficiency for the atomizing process was reduced. In a working solution containing sub-mol/L order of sulfuric acid, thinning or cracking of the graphite furnace progressed more rapidly and the function of it was greatly deteriorated.
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  • Disk-Shaped Crystal Grain in Poly-Si Film Prepared by Excimer Laser Annealing
    — Influence of Hydrogen in a-Si Film —
    Akira Heya, Naoya Kawamoto, Naoto Matsuo
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 134-138
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.134
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      The effects of hydrogen in a-Si film on the growth of disk-shaped grain formed by excimer laser annealing (ELA) were investigated. For the energy density of 2500 J/m2, the disk-shaped grain was not observed by scanning electron microscope. On the other hand, at the energy density of 3000 J/m2, the disk-shaped grain was observed. The size of textured grain increased with increasing shot number. The area density of disk-shaped grain was constant in spite of increment of the shot number. In addition, the shot-number dependence of strain and crystal orientation differed between poly-Si films with and without disk-shaped grain. It is considered that the nucleation and growth of disk-shaped grain were suppressed by hydrogen. It is expected that the position and density of the disk-shaped grain can be controlled by hydrogen in a-Si film.
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  • Hydrogenation Reactions of A6061 Alloys at Ultra-High Pressures
    Hiroyuki Saitoh, Akihiko Machida, Yoshinori Katayama, Katsutoshi Aoki, ...
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 139-143
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.139
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      Hydrogenation pressure-temperature conditions of A6061 alloys were investigated at ultra-high pressures. Hydrogenation of these alloys at 550℃ and above 6 GPa formed AlH3. This pressure was two orders of magnitude higher than the pressure where these alloys were used as hydrogen storage vessels for fuel cell vehicles. Thus, it was concluded that A6061 alloys were not hydrogenated at the pressure-temperature conditions where hydrogen storage vessels were used.
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  • Thermodynamic Consideration on Multi-Step Hydrogenation of Mg17Al12 Assisted by Phase Separation
    Masashi Sato, Shintaro Asakura, Toshiro Kuji
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 144-147
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.144
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      The multi-step hydrogenation and dehydrogenation on the pressure-composition-temperature relations for the Mg17Al12-H system was thermodynamically discussed on the based upon the enthalpy for Mg-Al alloy recombination during corresponding reaction with hydrogen. Pressure-composition-temperature diagrams were measured Mg17Al12-H system by means of the volumetric technique in the temperature range of 598-648 K. The isotherms show two step hydrogenation and dehydrogenation indicating a disproportionate formation of MgH2 via Mg2Al3 intermetallic phase. The decomposition of Mg from the intermetallic phase causes thermodynamic destabilisation for the formation of Mg hydrides. The molar enthalpies of hydride formation for the investigated systems are: ΔHf=−38.5±0.9 kJ(molH)−1 for the Mg-H system; ΔHf=−36±1 kJ(molH)−1 for the first-step hydrogenation in Mg17Al12; ΔHf=−31±1 kJ(molH)−1 for the second-step hydrogenation in Mg17Al12.
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  • Mechanical Properties of Inconel 718 Nickel-Based Superalloy around Solidus Temperature
    Tsubasa Ohashi, Ryosuke Goto, Kenji Muto, Makoto Yoshida
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 148-154
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.148
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      Nickel-based superalloys have been applied to gas turbine and aircraft jet engine parts due to superior high temperature strength and corrosion resistance. However, casting defect such as solidification cracking often occurs. In order to increase productivity of precision casting and various shape casting processes, predicting the occurrence of solidification cracking by using CAE(Computer Aided Engineering) should be essential. Therefore, it is necessary to obtain mechanical properties in the state of solid-liquid coexistence. In this study, we try to get high temperature (around solidus temperature) mechanical properties of the nickel-based superalloy such as Inconel 718 by using originally developed tensile test. In the previous reports, flat distribution of temperature in the gage length, and crack initiation strain were not ensured. On the other, the developed device ensured within 3℃ of the temperature distribution in the gage length as to the Inconel 718. Tensile strain was measured by using in-situ observation of marker on the surface of the specimen. As a result, Stress-Strain curve, crack initiation stress, and crack initiation strain of Inconel 718 were obtained.
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  • Metal Recovery from Printed Circuit Board Waste by Chlorination-Volatilization and the Volatilization Behavior of Metals
    Akira Hosoi, Kenichi Hiruta, Yasushi Takasaki, Atsushi Shibayama
    Article type: Regular Article
    2012 Volume 76 Issue 2 Pages 155-163
    Published: 2012
    Released on J-STAGE: February 01, 2012
    DOIhttps://doi.org/10.2320/jinstmet.76.155
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      Printed circuit boards of discarded personal computers, televisions, mobile phones and so forth contain many valuable metals. With the aim of recycling the valuable metals contained in printed circuit board waste (PCBW), the effect of temperature on the chlorination-volatilization of metals under chlorine gas flow was investigated. The experimental samples used consisted of two types of powder: crushed PCBW made from PCs and other machines and roasted PCBW, made by roasting PCBW at 700℃. The principal element in crushed PCBW and roasted PCBW was copper, with contents of about 13 mass% and 20 mass%, respectively. Crushed PCBW contained elemental metals such as copper, tin and lead. In contrast, roasted PCBW consisted of oxides such as copper oxide, tin dioxide and silicon dioxide. The two types of sample were heated at temperatures ranging from 300℃ to 900℃ in chlorine gas. It was found that copper in crushed PCBW began to volatilize at 600℃ and was almost completely volatilized at 700℃ by chlorination-volatilization, whereas in roasted PCBW, copper started to volatilize at 600℃ and reached 100% volatilization at 800℃. For crushed PCBW, zinc reached about 85% volatilization at 500℃, while for roasted PCBW, zinc volatilization reached a maximum of only about 80% at 600℃. Lead and nickel also exhibited similar behavior. Consequently, the volatilization rate of crushed PCBW is higher than that of roasted PCBW, and the temperature dependence of the volatilization rate was verified for copper, lead, zinc, nickel, antimony and chromium. The volatilization rate of these metals increased with the temperature. It is thought that chlorination-volatilization is accelerated by the effect of carbon, which is included in crushed PCBW. In this study, the volatilization behavior of some of the valuable metals in PCBW in chlorine gas was observed.
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