Mullite interaction with bismuth oxide from minerals and sol-gel processes

作者：Gridi Bennadji F; Zimova J; Laval J P; Blanchart P^*

来源：Ceramics International, 2010, 36(1): 129-134.

DOI：10.1016/j.ceramint.2009.07.021

• Ceramics
• Chemical synthesis
• Phase equilibria

Mullite compounds with bismuth oxide in the SiO(2)-Al(2)O(3)-Bi(2)O(3) ternary system were synthesized from TEOS (C(2)H(5)O)(4)Si, aluminum nitrate Al(NO(3))(3)center dot 9H(2)O and bismuth nitrate Bi(NO(3))(3). Thermal and structural transformations were studied at temperatures ranging from 1000 to 1400 degrees C. The coexistence of Al(4)Bi(2)O(9) and Bi(4)Si(3)O(12) phases at temperatures up to 1000 degrees C was observed in compositions containing 5-31 mol% Bi(2)O(3). Mullite is observed at temperature higher than 1000 degrees C in composition not exceeding 5 mol% of Bi(2)O(3). Corundum coexist with a liquid above 1000 degrees C in all compositions containing more than 5 mol% Bi(2)O(3). The liquid temperature is slightly above 1000 degrees C for all compositions. A tentative pseudo-binary diagram mullite-Bi(2)O(3) is proposed. A similar system was studied with silico-aluminate compositions containing kaolinite and muscovite minerals. The occurrence of a liquid when Bi(2)O(3) is added highly favors the mullite growth at temperature below 1200 degrees C. It is favored by local concentrations at interfaces of a transient liquid phase, which enhance the mobility of species.

• 出版日期2010-1