• Journal of the Korean Ceramic Society
• /
• v.41 no.1
• /
• pp.51-56
• /
• 2004

Mullite whiskers were synthesized using $Al(OH)_3$, amorphous $SiO_2$ and $AIF_3$ as starting materials by a vapor-solid reaction at relatively low temperature of $1100^{\circ}C$. Leaflet Fluorotopaz was observed for the specimen heat-treated at $800^{\circ}C$. Fluorotopaz was decomposed at $1000^{\circ}C$ and only mullite phase was observed for the specimen sintered at $1100^{\circ}C$ and above. It was found that the synthesized mullite at $1200^{\circ}C$ had grown to [001] direction and side planes were the {110}. The distance of (110} plane was $5.34^{\AA}C$. The amounts of $Al_2O_3$ in mullite was 73.56(1.39)wt%.

• Korean Journal of Materials Research
• /
• v.15 no.10
• /
• pp.644-651
• /
• 2005

The thermal analysis of $Al(OH)_3-SiO_2-AIF_3$ system was done. The thermal behaviors of components and the effect of moisture on the formation of mullite were investigated via TG-DTA and XRD analysis. The mixture of $Al(OH)_3,\;SiO_2,\;AIF_3$showed two endothermic peaks with drastic weight loss and one exothermic peak. Fluorotopaz was formed at $800^{\circ}C$ and turned into mullite completely at $1100^{\circ}C$. But the mixture $Al_2O_3$ of or dehydrated $Al(OH)_3$ and $SiO_2$ could not form mullite even at $1200^{\circ}C$ in which the crystalline phases were $\alpha-Al_2O_3$ ana cristobalite. It was found that the synthesized mullite was aciculate shaped single crystalline whisker.

• Journal of the Korean Ceramic Society
• /
• v.43 no.6 s.289
• /
• pp.376-382
• /
• 2006

In the $Al(OH)_3-SiO_2-AlF_3$ system, leaf-shaped fluorotopaz was first formed at $800^{\circ}C$ and mullite whisker was formed at $1,100^{\circ}C$. The mass transportation of Al and Si as gas phase, the fast reaction and growth, and the absence of liquid phase existence in mullite whisker showed that the formation and growth of mullite was from the solid-vapor reaction.