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
针对Na_(2)O-CaO-SiO_(2)(NCS)多孔微晶玻璃内部气孔大小不同、分布不均问题,提出通过添加固态Si颗粒调控NCS多孔微晶玻璃孔结构。通过扫描电子显微镜(SEM)、图像处理软件Image pro plus 6.0、DSC等分析手段研究固态Si颗粒对NCS多孔微...针对Na_(2)O-CaO-SiO_(2)(NCS)多孔微晶玻璃内部气孔大小不同、分布不均问题,提出通过添加固态Si颗粒调控NCS多孔微晶玻璃孔结构。通过扫描电子显微镜(SEM)、图像处理软件Image pro plus 6.0、DSC等分析手段研究固态Si颗粒对NCS多孔微晶玻璃内部热场、液相的影响,以及Si颗粒调控NCS多孔微晶玻璃气泡成核机制。结果表明,通过加入固态Si颗粒可以使NCS多孔微晶玻璃基础配合料内部热扩散速率提高23.5%,NCS多孔微晶玻璃内部液相产生温度降低60℃,液相产生速率增大7~8倍;在固态Si颗粒周围先产生液相,液相中的气泡分子在固态Si颗粒表面非均相成核,随着配合料温度的升高,无固态Si颗粒位置处产生新的液相,液相中气泡分子扩散至固态Si颗粒表面促进原始气泡长大或者在新液相中均相成核。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.
文摘针对Na_(2)O-CaO-SiO_(2)(NCS)多孔微晶玻璃内部气孔大小不同、分布不均问题,提出通过添加固态Si颗粒调控NCS多孔微晶玻璃孔结构。通过扫描电子显微镜(SEM)、图像处理软件Image pro plus 6.0、DSC等分析手段研究固态Si颗粒对NCS多孔微晶玻璃内部热场、液相的影响,以及Si颗粒调控NCS多孔微晶玻璃气泡成核机制。结果表明,通过加入固态Si颗粒可以使NCS多孔微晶玻璃基础配合料内部热扩散速率提高23.5%,NCS多孔微晶玻璃内部液相产生温度降低60℃,液相产生速率增大7~8倍;在固态Si颗粒周围先产生液相,液相中的气泡分子在固态Si颗粒表面非均相成核,随着配合料温度的升高,无固态Si颗粒位置处产生新的液相,液相中气泡分子扩散至固态Si颗粒表面促进原始气泡长大或者在新液相中均相成核。
