ZHAO Shike, HUANG Yong, HUANG Xiaoxian, GUO Jingkun

( Tsinghua University,＊Shanghai Institute of Ceramics,Chinese Acdademy of Science)

Abstract: The literatures in the past decades,with respect to mullite formation by reaction sintering of Al₂O₃ SiO₂ containing mixed powders,were reviewed in this paper, and the factors affecting mullite formation mechanism were discussed .It is indicated that the nucleation and growth of mullite is closely related to reaction temperature and properties of starting materials .At low temperature,mullite formation occurs by nucleation and growth within the aluminosilicate phase formed by reaction betweenAl₂O₃ and SiO₂ , and the growth rate is controlled by the dissolution of Al₂O₃ .At high temperature, however, mullite will nucleate and grow at the point of contact between Al₂O₃ and SiO₂ particles, and the rate -controlling step is the diffusion of Al^{3 +} and Si⁴⁺ through mullite crystal lattice .A crossover temperature, at which mullite formation mechanism begin to tranform, is suggested to be between 1350 ℃ and 1650 ℃.

Keywords: mullite, reaction -sintering, mullite formation mechanism