常压开放水热法制备莫来石复相纳米晶体

SYNTHESIS OF MULLITE NANOCOMPOSITES BY THE OPEN-SYSTEM HYDROTHERMAL CRYSTALLIZATION METHOD UNDER NORMAL PRESSURE

以天然高岭土为原料,先经氧化-还原精细化工艺,制备高岭土精矿粉。精矿粉(Si与Al的摩尔比为5:4)在1050～1100℃后煅烧得到莫来石。最后采用常压、开放水热晶化法,NaOH溶液浓度为4.0mol/L,在0～80℃升温1h,达到80℃后恒温2h,制备出粒径尺寸在80～100nm,颗粒均匀、分散性好、耐高温的莫来石复相纳米晶体。

Natural and raw kaolin was first processed to prepare fine kaolin powder using the oxidation-reduction refining method. The fine kaolin powder （the molar ratio of Si to AI 5：4） was then baked at 1 050-1 200 ℃ to produce mullite oxides. The mullite oxides were further synthesized into mullite nanocomposite using the open-system hydrothermal crystallization method. Under normal pressure, the mullite oxide product was mixed with NaOH solution that had a concentration of 4.0 mol/L. Then the mixture was heated for 1 h until the temperature reached 80 ℃. Heating was continued for 2 h, while the temperature was maintained at 80 ℃. The final product was a mullite nanocomposite with fairly homogenous grain sizes of 80-100 nm, and with excellent thermal stability.