2001 Fiscal Year Final Research Report Summary
Development of Rapid Sintering Technique on Metal Powder by Considering the Saving Energy and Environmental Pollution Plan
| Project/Area Number |
11650729
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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 | Iwate University |
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Principal Investigator |
NAKAMURA Mitsuru Iwate Univ., Engineering, Associate Professor, 工学部, 助教授 (60237435)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Rapid sintering technique / High frequency induction method / Carbon steel / High strength-alloyed steel / vacuum condition / decarburized layer / Radial crushing strength / Total evaluation |
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| Research Abstract |
This research was purposed by rapid sintering process used the high frequency heating instrument that compared to conventional sintering furnace. Rapid sintering technique within a few minutes is to investigate 2 types of steels (carbon steel and high strength-alloyed steels). And, the research atmosphere changed to 3 types of vacuum, nitrogen and nitrogen-hydrogen. The results were obtained as follows.
1 Case of carbon steel under vacuum condition
There is very important factor both the removal of adsorbed gas in powder grain surface and accompanied by the diffusion and sintering of each powder. The isothermal treatment when the sintering process in this experiment was a key technology treatment. This method was finished to sinter only 3 minutes, and it's condition was maximum heating time-30 s, sintering condition 1523 K-60 s and isothermal treatment-90 s holding only.
2 Case of carbon steel under nitrogen gas atmosphere condition
It was important to release an adsorbed gas in iron powde
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r particle surface. The product of decarburized layer on specimen surface was a problem because of reduces of mechanical properties. This method was finished to sinter only 3.5 minutes, and the radial crushing strength (RCS) was obtained almost same value compared to conventional furnace method.
3 Case of carbon steel under nitrogen-hydrogen gas atmosphere condition
In the case, added low H2 gas concentration from 1 to 2 %, RCS and prevention of decaburization were almost same values compared to rapid sintering of 100 % N2 gas atmosphere. This lowering tendency of RCS was caused to form FeOOH compound by the present of H2 gas and this compound prevented to diffusion of Cu elements.
4 Case of high strength-alloyed steel under vacuum condition
This rapid sintering needs to control the degassing, diffusion of additional alloying elements and form a Martensite or Bainite structure in matrix and these are very important factor for the sintering process. It can be understood that this sintering process needs the highest sintering temperature compared with conventional furnace process but obtained comparatively higher RCS by changing the holding time. This process took only 3〜4 minutes for holding time, in spite of high strength-alloyed steel required longer time for diffusion of additional alloying elements. Less
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