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Volume 74, Issue 12
Displaying 1-8 of 8 articles from this issue
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Kazuma Miura, Yasunori Kobayashi, Takayuki Naito, Akihiro Yamada, Akir ...Article type: Regular Article
2010 Volume 74 Issue 12 Pages 771-778
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSIn order to develop corrosion resistance surface treatment method, we designed a chemical conversion treatment method which includes pretreatment to remove inclusions on a magnesium alloy and hydrothermal treatment to form the modifying layer.
One sample of MP1(ASTM: AZ31B) magnesium alloy was pretreated with hydrogen fluoride, followed by sodium hydroxide. Another sample was pretreated with sodium hydroxide, followed by sodium-gluconate solution. Then both samples were exposed to high temperature steam.
The number of inclusions, which may be Al-Mn intermetallic compound was dramatically reduced by both pretreatments. The hydrothermal treatment improved pitting corrosion resistance through the formation of the leather film which mainly consisted of magnesium hydroxide. The results of salt spray tests showed that the corrosion pits remarkably decreased after both pretreatments. Thus, the pitting-proof nature of the alloy was improved by combining chemical conversion and hydrothermal treatments.
In particular, the pretreatment of consisting of sodium hydroxide followed by sodium-gluconate solution, which is a toxic fluorine-free process, was found to be effective for use as a high corrosion resistance surface treatment method.
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Manako Tanaka, Masahiro Kitada, Masahiko NishijimaArticle type: Regular Article
2010 Volume 74 Issue 12 Pages 779-787
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSThe metallurgical microstructure and nonmetallic inclusions in the steel barrel of a Japanese percussion lock gun fabricated in the late Edo period have been investigated. The purpose of this work is to obtain metallographic data of the Japanese percussion lock gun, and to clarify the manufacturing technique and raw material of the barrel. Test pieces are cut from the center and the muzzle of the barrel. The carbon concentration is determined by chemical analysis. The microstructure is observed using an optical microscope and a scanning electron microscope (SEM). The concentration of nonmetallic inclusions is obtained by electron dispersive X-ray analysis (EDS). The carbon concentration is 0.003~0.2 mass% for the center of the barrel and 0.028~0.2 mass% for the muzzle of the barrel. The distribution of the nonmetallic inclusions in the steel shows that the barrel is fabricated from a single steel sheet. Nonmetallic inclusions in the center of the barrel are of a plural phase consisting of FeO, Fe2SiO4 and calcium-and phosphorus-rich matrix oxide. Nonmetallic inclusions in the muzzle of the barrel are classified into two types: a plural phase consisting of FeO and the matrix containing Fe-Si-O grains and glass, and a single phase of glass. The difference in the metallurgical microstructure and nonmetallic inclusions between the center steel and the muzzle steel shows that the barrel is made of different carbon-content steels. Since Ti is detected from the nonmetallic inclusions, it is thought that Japanese iron sand is used as the raw steel to fabricate the barrel.
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Miyoshi Ohara, Yorinobu Takigawa, Kenji HigashiArticle type: Regular Article
2010 Volume 74 Issue 12 Pages 788-793
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSTo develop an improved surface treatment for producing metallic luster on magnesium alloys by controlling surface roughness, we analyzed the angle of incidence ψ, the instrument acceptance angle Δθ and the root mean square slope m, for experimental results on specular glossiness Gs and root mean square roughness σ. First, we derived a theoretical equation from the theory of electromagnetic waves and a model of surface roughness, assuming that the root mean square roughness is much smaller than the wavelength of the incident radiation. In this equation, the ratio R/R0 of the specular reflectance of the specimens to the specular reflectance of a smooth surface indicates the sum of the specular reflection component and the scattering reflection component for the instrument acceptance angle. This reflectance is a function of the angle of incidence. In this study, angles of incidence of 20°, 60° and 85° were used. Next, the specular glossiness and the root mean square roughness were measured for the surface of AZ31 magnesium alloy specimens treated with acidic aqueous solution. The value of the root mean square slope was obtained from the theoretical equation and was compared with the experimental results. We found that the experimental results matched the results calculated for an angle of incidence of 20°. These results clarified that the reflectance R/R0 is a function of σ/λ, the angle of incidence ψ, the instrument acceptance angle Δθ and the root mean square slope m. These results will be useful for developing better surface treatments for producing metallic luster on magnesium alloys.
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Masaru Kanmera, Takuya Fujima, Ken-ichi Takagi, Yöhei Nakagomi, S ...Article type: Regular Article
2010 Volume 74 Issue 12 Pages 794-800
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSTo study effects of Cu and Sn addition on the sintering behavior of SUS304L stainless steel powders and mechanical properties of their sintered compacts, 4 mass% Cu and 1 mass% Sn pre-alloyed SUS304L stainless steel powder and 2 mass% Cu mixed this powder were sintered at 1323~1523 K in vacuum after compacted at the pressure of 490 MPa. In addition to density measurement, micro structural observation and tensile test for each sintered compacts, differential scanning calorimetry and thermomechanical analysis for each powder were conducted.
As a result, alloying elements of Cu and Sn in the powders were considered to generate liquid phase around 1150 K. Moreover, alloying elements of Ni in the powders was considered to react with Cu-Sn phase during sintering and resulted to form Cu-Sn-Ni liquid phase near 1400 K. These liquid phase led to the densification of the sintered compacts. The tensile strength of sintered compact of all powders sintered at 1523 K showed superior or comparable to the JIS value of bulk SUS304L.
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Shingo Kuriki, Ichiro Daigo, Yasunari Matsuno, Yoshihiro AdachiArticle type: Regular Article
2010 Volume 74 Issue 12 Pages 801-805
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSThe production of the platinum group metals (PGM) consumes large quantities of energy and induces a lot of carbon dioxide. The promotion of PGM recycling is important to construct a sound material-cycle society. In this article, a dynamic material flow analysis for PGM in Japan was conducted in order to evaluate the recycling potential of PGM. In Japan, PGM demand for autocatalyst accounted for about 50% of the total PGM demand in 2008. Therefore, this study focused on platinum, palladium, and rhodium used as autocatalyst. The amount of material stock regarding these autocatalysts were estimated during 1975-2008. The amount of these autocatalysts generated from end-of-life vehicles (ELV) were also estimated during 1988-2008.
As the result, the material stock of these metals as autocatalysts has monotonically increased during the investigated period. The amount of these autocatalysts generated from ELV has also increased, but the amount of recycled ones have been rather stable due to growing exportation of used automobiles, used auto engines, and used autocatalysts.
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Takashi Shintani, Yoshinori Murata, Yoshihiro Terada, Masahiko Morinag ...Article type: Regular Article
2010 Volume 74 Issue 12 Pages 806-810
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSMetallic materials suffering deformation store elastic strain. Evaluation of this strain energy is important for understanding the mechanical and physical properties of materials. Although direct evaluation of the stored energy is difficult, it can be evaluated by determining the defect energy of dislocations induced by the deformation. Thus, a practicable method of evaluating the strain energy is to measure the dislocation density in metallic materials. The average and representative dislocation density can be estimated by X-ray diffraction (XRD) analysis. We have estimated the dislocation density of a magnesium alloy with hexagonal crystals by a modified Warren-Averbach analysis based on a modified Williamson-Hall plot using XRD profiles. The dislocation density value obtained by this method agrees with those reported previously. We find that the modified Warren-Averbach method is still a powerful method for evaluating the dislocation density in hexagonal crystals.
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Eiji Yamasue, Ryota Minamino, Ichiro Daigo, Hideyuki Okumura, Keiichi ...Article type: Regular Article
2010 Volume 74 Issue 12 Pages 811-819
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSTotal materials requirement (TMR) for the recycling of materials (Urban Ore TMR) from end-of-life electric home appliances (cathode ray tube TV, liquid crystal display TV, refrigerator, washing machine, air conditioner and microwave oven) have been estimated and evaluated. The estimation were carried out using scenario analyses, in which the number of recycled elements and/or materials was changed considering additional energy for advanced recycling. As the results of the estimation, the urban ore TMR of gold, silver, copper and stainless steel were lower than TMR when they are smelted from natural ore (natural ore TMR) for all the scenarios. The urban ore TMR for iron (steel), aluminum and die-casting aluminum were mainly affected by the dilution ratio using pure element for the recycling. The recyclability of the elements and materials are discussed from the view point of TMR.
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Koki Asari, Koji KakehiArticle type: Regular Article
2010 Volume 74 Issue 12 Pages 820-825
Published: 2010
Released on J-STAGE: December 01, 2010
JOURNAL FREE ACCESSThe effect of crystallographic orientation on the tensile/compressive creep strengths of single crystals of a nickel-based superalloy was examined at 750°C under the constant nominal resolved shear stress for {111}<112> slip system. Initial orientations of tensile/compressive specimens were selected within 10 deg of the [001] pole. The {111}<112> type slip systems were found to be operative during the tensile/compressive creep deformations. The orientation dependence of creep strength and deformation mechanisms were different between tension and compression. The dominant deformation mode in tension was occurred by {111}<112> viscous slip; however, the creep mechanism in compression was twin formation associated with viscous {111}<112> slip.
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