2006 Fiscal Year Final Research Report Summary
Establishments of sintering theory of powder metal hollow spheres and process for cell structures
| Project/Area Number |
16560636
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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 | Kagawa University |
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Principal Investigator |
SHINAGAWA Kazunari Kagawa University, Faculty of Engineering, Assistant. Professor, 工学部, 助教授 (30215983)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Cell structures / Ultra light metals / Sintieting / Powder metallurgy |
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| Research Abstract |
The deformation behavior of metallic hollow spheres (MHSs) at elevated temperatures is examined by numerical analysis and experiments for a unit cell model as a basis of building up a constitutive equation for the firing process of MHS compacts. Changes in terms of reductions in height, contact area and equatorial diameter in compression under a constant load are clarified for a single hollow sphere with various shell thicknesses by viscoplastic finite element (FE) analysis. Compression tests for the real unit cell, made of eight iron hollow spheres, are performed at high temperatures by using a thermomechanical analyzer (TMA) to verify the numerical calculations. The material constants are also determined, by similar compression tests, for bulk specimens made from the same iron powder as the MHS material. The compressive behavior of the iron hollow sphere structure at elevated temperatures can be described well by the FE model with a diffusional creep law.
Geometrical change in metallic hollow spheres (MHSs) during compression at elevated temperatures is formulated by using the results of the viscoplastic finite element analysis of a unit cell model. The parameters related to the viscosity, contact area and diametral area of MHSs are approximated by functions of the shell thickness, and placed into a constitutive equation for the sintering of powder particles. Pressure sintering of iron hollow sphere compacts is also performed in a tube with weights. The reduction in height of the compacts varies with the shell thickness of the MHS and the pressure and temperature during sintering. The compressive behavior of the compacts in the firing process is predicted well by the proposed constitutive equations.
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