Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures...Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures and textures of porous glass-ceramics are investigated by using differential thermogravimetric analysis/differential thermal analysis ( TGA/SDTA) ,X-ray diffraction ( XRD) ,and scanning electron microsco- py ( SEM) . The activity energy of crystallization ( E) and crystallization kinetics parameter ( k) were calculated based on the modified JMA equation. The Avrami parameter n was obtained according to Augis-Bennett function. The results show that the k value of No. 1 sample ( SiO2 /CaO = 61∶ 18) is the largest among all samples, which tends to crystallize more easily,and crystallization processes of all samples are observed bulk crystallization. The main crystal phase observed is parawollastonite ( clinorhombic system) with puncheon shape. Poreforming agents decomposed at 100 - 500 ℃ form a large number of closed pores with micron dimension and several semi-open pores distribute uniformly in the glass-ceramics matrix. This work may be expected to be favorable for industrial scale applications of porous glass-ceramics in the field of building thermal insulation.展开更多
基金Sponsored by the Ministry of Science & Technology of China During the 11th Five-year Plan (Grant No. 2006BAJ05B07)
文摘Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures and textures of porous glass-ceramics are investigated by using differential thermogravimetric analysis/differential thermal analysis ( TGA/SDTA) ,X-ray diffraction ( XRD) ,and scanning electron microsco- py ( SEM) . The activity energy of crystallization ( E) and crystallization kinetics parameter ( k) were calculated based on the modified JMA equation. The Avrami parameter n was obtained according to Augis-Bennett function. The results show that the k value of No. 1 sample ( SiO2 /CaO = 61∶ 18) is the largest among all samples, which tends to crystallize more easily,and crystallization processes of all samples are observed bulk crystallization. The main crystal phase observed is parawollastonite ( clinorhombic system) with puncheon shape. Poreforming agents decomposed at 100 - 500 ℃ form a large number of closed pores with micron dimension and several semi-open pores distribute uniformly in the glass-ceramics matrix. This work may be expected to be favorable for industrial scale applications of porous glass-ceramics in the field of building thermal insulation.
