The role of MgO in the thermal behavior of MgO–silica fume pastes
详细信息 查看全文
- 作者：Zhaoheng Li ; Qijun Yu ; Xiaowen Chen ; Hao Liu…
- 关键词：MgO ; Silica fume ; M–S–H ; Mg(OH)2 ; Refractories
- 刊名：Journal of Thermal Analysis and Calorimetry
- 出版年：2017
- 出版时间：March 2017
- 年：2017
- 卷：127
- 期：3
- 页码：1897-1909
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Physical Chemistry; Analytical Chemistry; Polymer Sciences; Inorganic Chemistry; Measurement Science and Instrumentation;
- 出版者：Springer Netherlands
- ISSN：1588-2926
- 卷排序：127
文摘
The compounds of MgO–silica fume (SF) pastes constitute magnesium silicate hydrate (M–S–H) in a new generation of basic castables. However, Mg(OH)2 is a common reaction product with the formation of M–S–H. This study aims to reduce the formation of Mg(OH)2 in MgO–SF pastes. In this study, MgO powders were prepared by calcining magnesite at different temperatures and then mixed with SF and water to prepare MgO–SF pastes. The properties of MgO powders were characterized, and the pH values in the pore solutions of MgO–SF pastes were measured. The MgO–SF pastes cured for 90 days were calcined at 500, 700, 900 and 1200 °C, and the microstructure was characterized afterward. The results showed that both the reactivity of MgO powders and the pH value of the pore solution of MgO–SF pastes were diverse, which essentially depended on the grain sizes and the crystalline degree of MgO. Increasing the calcination temperature of MgO was beneficial to reduce the formation of Mg(OH)2 or even stop it when using MgO calcined at 1450 °C. Enstatite and forsterite formed for all MgO–SF pastes after calcination. However, the microstructure of MgO–SF paste with MgO calcined at 1450 °C was denser than others. MgO–SF pastes were suitable for the new-generation refractory castables. Notably, using MgO calcined at 1450 °C is more appropriate.