1991 Fiscal Year Final Research Report Summary
Preparation of Multi-layered Ceramic Particles
| Project/Area Number |
02650564
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
無機工業化学・無機材料工学
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| Research Institution | Okayama University |
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Principal Investigator |
OSAKA Akiyoshi Fac. Eng., Okayama Univ., Assoc. Prof., 工学部, 助教授 (20033409)
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| Co-Investigator(Kenkyū-buntansha) |
NANBA Tokurou Fac. Eng., Okayama Univ., Res. Assoc., 工学部, 助手 (80218073)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Ceramic particle / Multi-layer / Spray pyrolysis / Hydroxyapatite / Hematite |
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| Research Abstract |
The microstructures or surface morphology of ceramic particles depend on the preparation procedure and conditions, and thus their properties vary, accordingly. With utilizing such flexibility one can control the microstructure of the particulate and prepare ceramic particles which have a multi-layered or tailored microstructure. This study aims to clarify the dependence of the microstructure of of the ceramic particles through ultrasonic-spray pyrolysis on the experimental conditions.
Hematite particles were first prepared by ultrasonic spraying aqueous solutions ferric nitrate. The surface was smooth for the particles out of the solutions without additives (glycerol). Larger particles were hollow with a thick shell, while medium sized particles were dense. The solutions with the additive yielded hollow particles with a thin shell, and dimples were observed on the shell which were caused by the release of decomposed gas out of the particles.
Hydroxyapatite (HAP) Particles were prepared by ultrasonic spray-pyrolysis of aqueous solutions of calcium lactate or acetate, ammonium dihydrogen orthophosphate with EDTA as the chelating agent. The surface morphology of the particles depended on the experimental conditions while the rough surface was observed for the well-calcined particles. The particles were about 0.5mum in diameter.
With those aqueous solutions HAP-hematite composite particles were prepared through the ultrasonic spray pyrolysis where the molar ratio HAP/hematite was 1/0.5-1/9. The average diameter ranged from 0.2 to 0.6mum. With larger HAP content the surface was wrinkled or dimple-full, while the smooth surface was for the particles with greater hematite contents. A shell-nuclear type double layer structure was confirmed for larger particles (>O. 8mum in diameter). Such layered structure was built by initiating the HAP precipitation on the surface of the droplets due to breakage of Ca-EDTA chelate bonding.
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