煅烧对微硅粉性能的影响

采用同步热分析法、X射线衍射、扫描电镜、比表面积和白度等测试手段对煅烧前后的微硅粉样品进行了分析.实验结果表明:在600℃、4 h煅烧时微硅粉的除碳效果最佳,煅烧后样品中碳的质量分数由1.96%下降到0.65%;样品主要成分二氧化硅晶体结构并未变化,仍旧为非晶态,煅烧后仍出现了碳化硅的特征峰,表明煅烧去除的主要为游离碳;微观形貌分析表明,煅烧后样品微观颗粒粒径在长大,片状物质的含量却明显减少,但是组成颗粒的一次粒子长大并不明显;比表面积测试表明煅烧前后比表面积变化不大,但白度由31.04提高到70.14.

Influence of calcinations on performance of silica fume

The uncalcined and calcined samples were researched by simultaneous thermal analysis,X-ray diffraction, scanning electron microscope, Brunner-Emmet-Teller measurements, whiteness and other tests. As a result,the optimal calcination process is 600 ℃ ,4 h. The content of free carbon in silica fume drops from 1.96% to 0.65% ,and the crystal structure of the main composition-silicon dioxide still is a- morphous. The characterislic peak of silicon carbide appears both in uncalcined and calcined , which shows that the calcination method is just used to remove the free carbon. Microstructure analysis shows that the size of micro particles of the calcined samples grows up and the content of the flake material decreases significantly,but the primary grains do not get bigger. Area results show that the surface area of the samples is not changed. However,the whiteness increases from 31.04 to 70.14.