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Journal of the Korean Ceramic Society 1995;32(4): 455. |
| Oxalate 공침법에 의한 $beta$-Alumina 합성과 결정화 거동 |
| 박용민, 양유철, 김형욱, 박성수, 손영국 |
| 부산대학교 공과대학 무기재료공학과 |
| Synthesis of $beta$-Alumina By Oxalate Coprecipitation Method and Its Crystallization Behavior |
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| ABSTRACT |
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To investigate the synthesis of $beta$-Al2O3 and its crystallization behavior by oxalate coprecipitation method, the optimum pH range for oxalate coprecipitates has been theoretically calculated from the solubility products and the equilibrium constans of each metal ionic species and their solubility diagram wa obtained. The optimum pH range for oxalate coprecipitates at room temperature was estimated as <4. In experiment, we found that the optimum condition for oxalate coprecipitates was pH<1, which was not doped with pH controller. The Na+ ions were easily exchanged for the NH4+ ions of NH4OH which was used as pH controller, and those NH4+ ions were supposed to affect the crystallization behavior of $beta$-Al2O3. The thermal decomposition of all complexes was almost complete below 40$0^{circ}C$. The primary product of the decomposition process was m-Al2O3, which transformed to $beta$"- or $beta$-Al2O3 at temperature higher than 100$0^{circ}C$. We found that the powder prepared at 120$0^{circ}C$ had only $beta$"- and $beta$-Al2O3.EX>-Al2O3. |
| Key words:
${\beta}$-alumina, Oxalate coprecipitation, Synthesis, Crystallization |
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