1996 Fiscal Year Final Research Report Summary
A New Production Process of Functional Cerium Sulfide by Sulfurization of Cerium Oxide
| Project/Area Number |
07650863
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Metal making engineering
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| Research Institution | Muroran Institute of Technology |
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Principal Investigator |
SHIMAKAGE Kazuyoshi Muroran Institute of Technology Faculty of Eng Professor, 工学部, 教授 (70005346)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAI Shinji Muroran Institute of Technology Faculty of Eng Associate Professor, 工学部, 助教授 (10208796)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Cerium Sulfide / Cerium Oxide / CS_2 Gas / Sulfurization / Synthesis / Sintering / Functional Materials / Activation Energy |
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| Research Abstract |
In the present study, an attempt has made to synthesized Ce_2S_3 powder at a lower temperature and to elucidate the densification behavior for the sintering of synthetic powders. At first, sulfurization reaction of CeO_2 powder using CS_2 gas instead of H_2S gas was examined for preparing Ce_2S_3 powder. CS_2 gas can be handled easily than H_2S gas since it is a volatile liquid and less virulent. Moreover, it is expected to lower the reaction temperature of the sulfurization. Appropriate conditions for preparing a single phase of each polymorphic forms of Ce_2S_3 were established by sulfurization reaction of CeO_2 powder using CS_2 gas. Second, hot-pressing was also attemped by using synthetic Ce_2S_3 powder to fabricate the sintered compact, and the densification behavior was discussed.
CeS_2 was formed in the initial stage of reaction at temperature of 923K and above, and alphaalpha-Ce_2S_3 was finally formed for a shorter period of time at higher temperatures instead of CeS_2. The single phase of alpha-Ce_2S_3 could be synthesized by sulfurization reaction at 973K for 28.8ks. Since the formation of alpha-Ce_2S_3 was accelerated by the addition of carbon black to the CeO_2 powder, the carbothermic reduction was considered to become a dominant reaction with an increase in temperature. The densification behavior of beta-Ce_2S_3 powder prepared by vacuum heating of alpha-Ce_2S_3 was also examined under hot-pressing. Since grain growth was suppressed at a relative density range from rho=0.77 to rho=0.88, kinetic analysis of sintering was made by using the data in this region.
As a results, it was found that sintering kinetics were best explained by a grain-boundary diffusion mechanism with an apparent activation energy of 382kJ/mol.
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