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借助于X射线荧光仪、场发射扫描电子显微镜、能谱仪、X射线衍射仪和激光粒度仪研究了3种不同产地的氧化硅微粉在常温和800～1200℃热处理3h后的形貌、粒径分布、相变和熔融行为。常温下3种氧化硅微粉均为粒径小于1μm的圆球,可分辨的圆球粒径为30～50nm,部分小球黏附在大球表面。圆球粒径大小不同,粒径大于1μm的多为团聚体。所有氧化硅微粉热处理至800℃都为非晶态,至900℃热处理后开始方石英化,1 200℃热处理后生成鳞石英。800℃热处理后,部分氧化硅微粉出现轻微黏结现象,随温度升高出现变形和熔融软化,在1 200℃热处理3 h后,所有氧化硅微粉均呈熔融状。不同氧化硅微粉的相变和熔融行为与粒径分布和Na2O、K2O的含量有关,含ZrO2的氧化硅微粉经900℃热处理3h后出现t-ZrO2,温度继续升高后未观察到进一步相变。
The morphology, particle size distribution and microstructure of three kinds of silica powders at different temperatures were investigated by means of X-ray fluorescence spectrometer, field emission scanning electron microscope, energy dispersive spectrometer, X-ray diffraction and laser particle size analyzer Path distribution, phase transition and melting behavior. At room temperature, the three kinds of silica powders are all spherical with the diameter less than 1μm. The diameter of the distinguishable spherical particles is 30 ~ 50nm, and some of them adhere to the surface of big ball. Spherical size of different particle size more than 1μm mostly aggregates. All of the silica powders were heat-treated to 800 ℃ and were amorphous. After calcination at 900 ℃, cristobalite began to be formed and calcined at 1200 ℃. After heat treatment at 800 ℃, some of the silica powders showed slight sticking phenomenon. With the increase of temperature, deformation and melt softening occurred. All the silica powders were molten after heat treatment at 1 200 ℃ for 3 h. The phase transition and melting behavior of different silica powders are related to the particle size distribution and the content of Na2O and K2O. The ZrO2-containing silica powders showed t-ZrO2 after heat treatment at 900 ℃ for 3h and no further phase transition was observed .