1996 Fiscal Year Final Research Report Summary
Study on joining of single crystals of refratory metal by using brazing material with high melting-point
| Project/Area Number |
06650820
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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 |
Material processing/treatments
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| Research Institution | Okayama University of Science |
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Principal Investigator |
HIRAOKA Yutaka Okayama University of Science Faculty of Science Professor, 理学部, 教授 (70228774)
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| Project Period (FY) |
1994 – 1996
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| Keywords | refratory metal / ceramics / joining between dissimilar materials / brazing / mechanical properties / resistance against circumstance / microstructure |
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| Research Abstract |
1.Brazing of single-crystalline molybdenum by using Mo-40%Ru alloy
Preparation of sheets of Mo-40%Ru or Mo-40%Ru-B alloys by powder metallurgy was not successful. Then brazing of single-crystalline molybdenum was performed by using mixture of powders and organic solvent. The joint strength gradually increased by adding boron as small as 2%, and was as high as that of the bulk Mo crystal. Additonally the joint was "full-bended" until a bend angle of 100ﾟand was not failed at room temperature. This result reggests the toughness of Mo-40%Ru alloy was substantially improved by a small addition of boron.
2. Brazing between single-crystalline molybdenum and carbon-ceramics
By using palladium, platinum or zirconium, the brazed joint between single-crystalline molybdenum and carbon-ceramics demonstrated a strength as high as 100MPa. Investigation by EPMA suggested the joint strength depends on both composition and pores particularly near the surface.
3. Degradation of the joint strength in a simulated atmosphere
The brazed joints mentioned above should be used in a relatively high-temperature circumstance for a prolonged period. Thereby the specimen was kept in a vacuum at high temperature and the change of structure, composition and strength of the brazed joint was examined. The brazed joints by using Mo-40%Ru-1%B alloy demonstrated a ductility, though small, and a higher strength than that by using Mo-40%Ru alloy. The brazed joint between single-crystalline molybdenum and carbon-ceramics by using palladium or platinum demonstrated approximately a half of the original strength after heat treatment.
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