Low-Temperature Formation of α-Alumina by Doping of an Alumina-Sol

✍ Scribed by Hyuk-Joon Youn; Jin Wook Jang; In-Tae Kim; Kug Sun Hong

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 136 KB
• Volume: 211
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5977

✦ Synopsis

In our present study, the phase transition behavior of ␥-alumina doped by an alumina-sol was explored using X-ray powder diffraction and transmission electron microscopy. It was found that the addition of an alumina-sol into ␥-alumina enabled the onset of the ␥to ␣-alumina transformation at temperatures as low as 600°C. This phenomenon was designated as the "sol-effect." Although the onset temperature of the phase transformation was very low, the transformation was completed at 1100°C which is the same as that observed with the seeding method. Further investigation revealed that the transformation was composed of two steps. One occurs over the temperature region from 600 to 950°C where a slow increase in the content of ␣-alumina is observed. The other is the region from 950 to 1100°C where a rapid increase of ␣-alumina occurs due to "self-seeding." The "soleffect" produces powders with very fine ␣-alumina particle sizes and little agglomeration.