微波水热时间对莫来石粉体的相组成和形貌的影响

Influence of Microwave Hydrothermal Time on Phase Composition and Morphology of Mullite Powders

以Al(NO3)3.9H2O、正硅酸乙酯为主要原料通过溶胶?凝胶法制备了前驱体干凝胶。采用微波水热(microwave hydrothermal,MH)法对该干凝胶进行了处理,并经过煅烧制备了莫来石粉体。借助差热分析、X射线衍射、Fourier变换红外光谱和扫描电子显微镜等分析测试手段表征了合成样品的组成和微结构,研究了MH时间对莫来石相组成及显微形貌的影响。结果表明:在微波温度为180℃,MH处理2 h的前驱体干凝胶,并经1 200℃煅烧3 h后,可以获得莫来石粉体;MH时间越长,所生成的莫来石相越多。MH时间同样对粉体的形貌有较大的影响,随着微波水热时间的延长,所得粉体逐渐由片状结构向针状结构转变,团聚减少,分散性增强。

Mullite gels prepared by a sol–gel method using tetraethyl orthosilicate and Al（NO3）3？9H2O as the raw materials were treated by microwave hydrothermal（MH） process at different time,and the mullite powders were finally obtained through calcination.The phase composition and microstructure of the powders were characterized by differential thermal analysis,X-ray diffraction,Fou-rier transform infrared spectrometer and scanning electron microscopy analysis.The influence of MH time on the phase composition and morphology of mullite were mainly investigated.Results show that mullite powder can be synthesized through precursor mullite gels treated by microwave hydrothermal（MH） process at 180 ℃ for 2 h and calcined at 1 200 ℃ for 3 h.More mullite powder can be synthesized with the increase of MH time.The MH time has greater impact to the morphology of mullite powder which changed gradually from sheet-like to pin-like,and its agglomeration decreases and the particle size becomes smaller with the increasing of MH time.