1998 Fiscal Year Final Research Report Summary
Transformation toughening of MoSi_2 with incorporation of PSZ by means of CVI
| Project/Area Number |
08650805
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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 |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
YOSHIKAWA Noboru Graduate School of Tohoku Unoversity, Reaserch associate, 大学院・工学研究科, 助手 (70166924)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Atsushi Graduate School of Tohoku Unoversity, Professor, 大学院・工学研究科, 教授 (00005307)
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| Project Period (FY) |
1996 – 1998
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| Keywords | MoSi_2 / ZrO_2 / transformation toughening / chemical vapor infiltration / metal organic precursor / microstructure |
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| Research Abstract |
This study was intended to fabricate high strength ZrO_2/MoSi_2 composites, which took advantage of transformation toughening. Chemical-Vapour-Infiltration(CVI) method was adopted for incorporation of ZrO_2 into partially sintered MoSi_2. In order to obtain fundamental knowledge for fabrication process and the microstructure of the composites, ZrO_2 were deposited with no additive oxides. Microstructures of post-annealed ZrO_2 were observed and the optimum annealing conditions for realizing transformation toughening were discussed. The following results were obtained.
1) Fine MoSi_2 grains were well-covered with CVI-ZrO_2 by using Metal-Organic(MO) precursor.
2) The infiltrated ZrO_2 were all amorphous, therefore post-annealing treatment was required. The post annealed ZrO_2 at 1073K for 3.6ks in air consisted of equi-axed grains of several 10nm in diameter. Existence of monoclinic ZrO_2 was observed and this microstructure suggests the limitation of annealing conditions.
3) Hardness increase was realized by increase of ZrO_2 into MoSi_2 and maximum hardness of 20GPa was obtained in the composites. High toughness was recognized by Vickers indentation and occurrence of transformation toughening was realized.
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