Research on the Preparation and Crystallization Action of Porous Glass-ceramics Based on CSA System

摘要

Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics is produced.The pegmatite is adopted as the main raw material.Five samples with different SiO2/CaO ration are used in the research.The mechanical properties,microstructures and textures of porous glass-ceramics are investigated by using many different testing measures including differential thermogravimetric analysis / differential thermal analysis (TGA/SDTA),x-ray diffraction (XRD),and scanning electron microscopy (SEM).Then,activity energy of crystallization (E) and crystallization kinetics parameter (k) are calculated based on the Modified Johnson-Mehl-Avrami (JMA) equation.The Avrami n parameter can be obtained according to Augis-Bennett function.The results show that: the k value of No.1 sample is the largest among the all samples,which tends to crystallize more easily,all samples'crystallization process are observed as bulk crystallization.And the main crystal phase is parawollastonite (clinorhombic system) with puncheon shape. Pore-forming agents decomposed at 100-500°C formed a large number of closed pores with micron dimension and several semi-open pores distributed uniformly in the glass-ceramics matrix.