托贝莫来石晶体的高温相变规律研究

Study on High-Temperature Phase Change of Tobermorite

通过差热分析(TGA/DSC)、X射线衍射分析(XRD)、傅里叶变换红外光谱分析(FTIR)等测试技术,对实验室制备的纯净托贝莫来石的高温相变规律进行系统的研究。DSC结果表明,托贝莫来石结构中有四个层间分子水,加热到300℃时四个层间分子水逐渐失去。当温度升高到724℃时,部分Si—O—H键断裂,失去羟基。XRD结果表明托贝莫来石晶体结构在724℃时已经破坏,衍射峰基本消失,煅烧后的样品为无定形的非晶态。当温度持续升高到861℃时,发生晶型重构,硅灰石晶体出现,结构转变为有序的、稳定的晶体结构。当温度到达1 000℃的时候,完全转变为2M型硅灰石晶体结构。托贝莫来石的高温相变经历了"托贝莫来石→脱水托贝莫来石→脱羟基托贝莫来石→硅灰石"一系列转变过程。

In the present paper,the high-temperature phase change of pure tobermorite was investigated by TGA/DSC,X-ray diffraction and infrared spectroscopy （ IR ） respectively.The DSC results showed that four interlayer water molecules were lost when they were heated at 300℃.As the temperature increased to 724 ℃,Si — O — H bonds were cleaved and dehydroxylation occurred.The XRD results showed that many diffraction peaks of tobermorite disappeared and the crystal structure was broken and collapsed.Then tobermorite tends to be disordered and amorphous.When the calcination temperature increased to 861 ℃,the disordered structure recombined to wollastonite,and the crystal structure became ordered and stable.Finally,the structure completely transformed to 2M-wollastonite at 1 000℃.It should include the process of high-temperature phase change of tobermorite ： tobermorite→dehydration tobermorite→dehydroxylation tobermorite→wollastonite.