Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 62, Issue 9
September
Displaying 1-9 of 9 articles from this issue
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Paper
Short Note
  • Thermoelectric Properties of layered FeSi2 Thermoelectric Conversion Module Produced by Spark Plasma Sintering Method
    Hironori SUZUKI, Yukihiro HIGASHI, Takuya YASUNO
    2015 Volume 62 Issue 9 Pages 457-461
    Published: September 15, 2015
    Released on J-STAGE: September 19, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.457
    JOURNAL OPEN ACCESS
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    The 5 pair layered FeSi2 thermoelectric conversion module was manufactured by sintering five layers of p type and n type powder at the same time, using SPS (spark plasma sintering) method. This process is expected to have higher reliability and shorter manufacturing time compared with conventional process which is performed by joining machined p type and n type element with the electrode. Maximum power of 32.4 mW was provided by this module under the condition of heating temperature 773 K and cooling temperature 293 K. The changes of the module shape and sintering condition greatly changed the performance of this module. By the optimization of the sintering condition and the shape, the performance of this process can be expected to be higher. To obtain the high performance it is necessary to develop the module shape which has large temperature difference with low electric resistance and sintering condition which enable low thermal conductivity with high density.
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Paper
  • Mechanical Properties and Corrosion Behavior of Fe/SiC Dispersed P/M Mg Alloy
    Shota KARIYA, Junko UMEDA, Hisashi IMAI, Haruo UNOSAWA, Manuel MARYA, ...
    2015 Volume 62 Issue 9 Pages 462-467
    Published: September 15, 2015
    Released on J-STAGE: September 19, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.462
    JOURNAL OPEN ACCESS
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    This study investigated the effects of Fe and SiC particle additions on mechanical properties and corrosion behavior of Mg-9 mass% Al-1 mass% Zn (AZ91) composite fabricated by powder metallurgy (P/M). The P/M forged AZ91-SiC composites showed noticeable increases in Young’s modulus and compressive yield strength compared to the monolithic AZ91 alloy, which was related to grain refinement and the content of SiC in the P/M composite. Corrosion rates of AZ91 matrix composites were further correlated to both SiC and Fe additions and the boundary length between AZ91 matrix and Fe particles. The insulating behavior of SiC particles also explained their smaller influence on the corrosion rate of P/M AZ91 compared with conductive Fe particles. The addition of SiC particles also inhibited the galvanic corrosion between AZ91 matrix and Fe particles. This study showed that corrosion rate of AZ91 may be controlled by the boundary length between AZ91 matrix and Fe particle.
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Special Issue: Improvement and New Development in Microstructure, Properties and Fabrication Process of Hard Material
Summarization
Memorial Lecture of JSPM Award
  • Development of Cemented Carbide for Tools
    Yutaka KUBO
    2015 Volume 62 Issue 9 Pages 471-477
    Published: September 15, 2015
    Released on J-STAGE: September 19, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.471
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    1. WC-0.40 mass%VN-0.44 mass%Cr3C2-8.0 mass%Co alloys using 0.4 micron WC powders were prepared by sintering and HIPing. In these alloys trace amount of V-rich phase were observed.
    Quantification of V-rich phases was performed as follows. (1) The location of V-rich phase was determined by EPMA and FE-SEM. (2) Cutting off and making thin film was done by FIB and determination of the size of V-rich phase was carried out by FE-TEM observation. (3) The threshold value was set by coincidation of the size by FE-TEM with peak width of EPMA line analysis. (4) EPMA V mapping image was binarized by the threshold value and area % was obtained by image analysis. The amount of V-rich phase in middle carbon alloy was 0.008area% and the amount of V-rich phase increased with increasing carbon content from 0.001 to 0.051area%.
    2. The start of melting as well as melting range in WC-31 mass%Co alloys were analysed by DTA measurement. They were significantly influenced by carbon content, start of melting for low carbon alloy and high carbon alloy were 1641 K and 1571 K respectively. Addition of Cr or V significantly lower the start of melting, especially for Cr added high carbon alloy. In case of Cr and V combined addition in solidification, there were two peaks suggesting two step solidification.
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Paper
  • Preparation for WC-FeAl Hard Metal Using FeAl2 and FeAl Powder
    Kiyotaka KATOU, Akihiro MATSUMOTO, Koji SHIMOJIMA, Hiroyuki HOSOKAWA, ...
    2015 Volume 62 Issue 9 Pages 478-484
    Published: September 15, 2015
    Released on J-STAGE: September 19, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.478
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    The preparation for WC-FeAl hard metal was investigated using FeAl2 (Fe-50 mass% Al) powder and pure-Fe powder as the materials of binder phase. Powder mixtures of WC, FeAl2 and pure-Fe which compositions were WC-25 vol% (Fe-X at% Al), (X = 0, 10, 20, 30, 40, 50, 67) were compacted to test-pieces and sintered in vacuum of 10−3 Pa order at 1050 °C,1250 °C and 1450 °C for 1 hr. By the analyses of SEM, XRD and WDS, the following results obtaind; (1) FeAl2 powder reacted with pure-Fe powder to FeAl alloy below melting point (1170 °C) of FeAl2. (2) On the microstructures of the WC-25 vol% (Fe-0, 10 and 20 at% Al) compacts sintered at 1450 °C, η-phase of W-Fe-Al-C was observed besides WC and FeAl alloy.
    Powder mixtures of (1) WC, FeAl2 and pure-Fe, (2) WC and FeAl (Fe-40 at% Al) alloy which composition was WC-25 vol% (Fe-40 at% Al) were wet-milled for 48 h. Sintered compacts were prepared using the milled powders. Transverse rupture strength and Vickers hardness of both compacts were almost equal level of 1.6 GPa and 1300 HV respectively when they were sintered at 1450 °C and 1475 °C. Both compacts had fine and homogeneous structures.
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  • Thermal Shock Examination of Cermets by Laser Irradiation and the Analysis—Evaluation of Deformation
    Tetsushi MATSUDA, Hideaki MATSUBARA
    2015 Volume 62 Issue 9 Pages 485-490
    Published: September 15, 2015
    Released on J-STAGE: September 19, 2015
    DOIhttps://doi.org/10.2497/jjspm.62.485
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    Titanium carbonitride (Ti(C,N))-based cermets have been studied for applying them to cutting tools and wear-resistant tools. Thermal shock resistance is an important property of tool materials used in severer thermal environment. However, evaluation method of thermal shock resistance has not been sufficiently established for cermets. In order to develop a method to evaluate the thermal shock resistance, irradiation experiments using a laser were conducted; laser beam was irradiated on the surface of thin specimens. The experimental results indicate that deformation of cermets by irradiation depends on the thermal properties, the mechanical properties and the plasticity of specimen. It is thought that the relationships between the deformation and the maximum temperature of cermets during irradiation characterize the material behavior under thermal shock environment.
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