| Project/Area Number |
02650479
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属精錬・金属化学
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
IGUCHI Yoshiaki Nagoya Institute of Technology, Materials Science and Engineering, Professor, 工学部, 教授 (00023268)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Shoji Nagoya Institute of Technology, Materials Science and Engineering, Research Assi, 工学部, 助手 (40024351)
IGUCHI Yoshiaki Nagoya Institute of Technology, Materials Science and Engineering, Professor (00023268)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1991: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1990: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | surface segregation / wustite / impurity / high temperatures / radius of metal ion / rate of segregation / reduction rate / CaO |
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| Research Abstract |
In this project started at 1990, we have been studying on the surface segregation of the oxides contained as impurity in wustite at high temperatures from 973K to 1223K, using a special hot-stage made by ourselves. Here, we describe the each item of results.
(1) High temperature surface segregation of impurity oxides : It was reported in the last year that CaO segregates on the surface of wustite in thermally equilibrated state. This year, we studied the surface segregation of MgO, Al_2O_3 and SiO_2. None of the three impurity oxides was evidensed to segregate at all. Furthermor, it is confirmed that MgO never segregates from the comparison of surface molar fraction to bulk one for MgO contained in sufficient amount. We are going to make analysis of Na_2O and K_2O at wustite surface finally in this course of project.
(2) Determination of the driving force surface segregation : We deduced the surface segregation to take place due to the relaxation of the strain energy piled up around the impurity metal ion substituting host metal ion. The valency different from that of host ion has been found to be ineffective to the segregation.
(3) Kinetics : Relatively fast achieving of equilibrium surface concentration was evidenced at the temperatures higher than about 923K, which is in accordance with the calculation by the McLean equation.
(4) Correlation with the reduction rate of wustite : The effect of CaO accelerating the reduction of wustite was concluded to bring about dute to its surface segregation.
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