利用偏高岭土为原料,以改性水玻璃溶液(摩尔比SiO2/Na2 O=1.0)为碱激发剂,按照产物中Si/Al=1.5(摩尔比)制备地质聚合物,60℃下养护3 d后脱模,在198℃下原位水热反应3.5 h得到由方沸石和地质聚合物组成的夹心型物质。利用X射线衍射( XRD)、扫描电镜( SEM)、N2吸附( BET)等手段对材料进行表征发现,质地均匀的地质聚合物膜片在进行水热反应后内部出现了分层现象,膜片内层的结构疏松,主要是方沸石,外层较为致密,仍为地质聚合物。推测夹心结构的形成机理如下：在水热过程中,外层的地质聚合物膜片中的游离钠离子以及其他养分溶解到水热母液当中,导致在膜片外层达不到晶体成核要求,而在内层可以形成晶核,当晶化条件达到后即可形成方沸石。%Geopolymer gels were prepared according to the designed composition ( Si/Al=1. 5 ) using metakaolin as raw materials and modified water glass (molar ratio of SiO2/Na2O=1. 0) as al-kali activator. Then the geopolymer gels were cured at 60 ℃ for 3 days to form the geopolymer. Through in-situ hydrothermal processing at 198 ℃ for 3. 5 h, a sandwich structure with geopolymers and zeolites was obtained. The analysis of XRD, SEM and BET were used for the characterization of the resulting product. The results indicated that the homogenous geopolymer membrane came to stratification. The sandwich layer was loose and mainly contained analcime. The parcel layer was dense and still composed of amorphous geopolymer. The formation mechanism of sandwich structure was presumed as follow:during the hydrothermal processing, Na+in the parcel layer diffused to the mother liquid, this indicated that there was no condition for the generation of analcime crystal, as a result, the analcime crystal core formed in the inner layer and grew into analcime crystal under suit-able conditions.
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