Effects of Na+ substitution Cs+ on the microstructure and thermal expansion behavior of ceramic derived from geopolymer
| Autor: | Xiaoming Duan, Jinsong You, Yu Zhou, Jingkun Yuan, Yao Zhang, Delong Cai, Shengjin Wang, Zhihua Yang, Dechang Jia, Xuzhao Liu, Peigang He |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Nucleation Analytical chemistry chemistry.chemical_element Mineralogy 02 engineering and technology engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Thermal expansion 0104 chemical sciences Amorphous solid Geopolymer Crystallinity chemistry Pollucite visual_art Caesium Materials Chemistry Ceramics and Composites engineering visual_art.visual_art_medium Ceramic 0210 nano-technology |
| Zdroj: | Journal of the American Ceramic Society. 100:4412-4424 |
| ISSN: | 0002-7820 |
| Popis: | As part of a series of studies, effects of Na+ substitution on the thermal evolution of cesium-based geopolymers on heating were studied. A series of sodium-substituted cesium-based geopolymers, Cs(1-x)NaxGPs (where x = 0, 0.1, 0.2, 0.3 and 0.4), were prepared and treated at 1300 °C for 2 h to obtain the corresponding ceramic products. The thermal evolution process was disclosed by virtue of a variety of technical, including TG-DTA, thermal shrinkage, XRD analysis, SEM and TEM investigation. The results indicated that unheated Cs(1-x)NaxGPs was not completely amorphous after the substitution of Na+ and the crystallinity of Cs(1-x)NaxGPs gradually increased with the rise of sodium content. Meanwhile, the average particle sizes of Cs(1-x)NaxGPs also increased evidently with increases in sodium substitution. The final product after heat treatment mainly consisted of pollucite (CsAlSi2O6) and amorphous glass phase. The particle size of pollucite grain gradually decreased as more Cs+ were replaced maybe owing to the role of Na+ in the nucleation process of pollucite. Two forms of Na+ present in the final products: A small portion was present in the pollucite grains due to Na+ partial occupied the crystallographic sites of Cs+; And the rest were present in the amorphous glass phase among the pollucite grains. The average coefficient of thermal expansion (CTE) of resulting Cs(1-x)NaxGPs ceramics increased from 4.80 × 10-6 K−1 (x = 0) to 7.26 × 10-6 K−1 (x = 0.4) with increases in sodium substitution, which could be due to the amorphous glass phase had a relatively higher CTE than that of pollucite. This article is protected by copyright. All rights reserved. |
| Databáze: | OpenAIRE |
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