亚微米板状α-Al_2O_3晶体的制备新方法(英文)

NOVEL METHOD FOR SUB-MICROSIZED α-Al_2O_3 PLATELETS

研究了微米级Al粉高温诱导Na2O-CaO-Si O2玻璃生成板状α-Al2O3晶体的形成过程并分别用X射线衍射仪及环境扫描电镜观察了生成晶体的形貌,用DSC/TG对混合粉体进行了热分析.X射线衍射分析及环境扫描电镜测试表明,1 200 ℃下,晶体直径为400 ～1 000nm,大部分呈聚集状态,部分晶体交互生长,且大部分的晶体发育于玻璃的界面,晶体与基体可以形成良好的润湿.DSC/TG表明,较低温下Al氧化后生成的γ-Al2O3转变为α-Al2O3,形成的α-Al2O3由于熔融的Al及玻璃提供的液相环境充分形核并生长,部分熔融的Al热侵蚀玻璃,导致玻璃的局部组成偏离Na2O-CaO-Si O2系统的三元组成,形成局部Na2O-Al2O3-Si O系统,并为形成NaAlSi O提供了必要条件.

α-Al2O3 platelets were prepared in the interface of Na2O-CaO-SiO2 glass induced by Al. Phase identification was accomplished by X-ray diffraction analysis （XRD）, The morphology of the piatelets was observed using an Environmehtal Scanning Electron Microscopy （ESEM）. The changes for the mixtures of the Al powders and the glass powders that occurred during heating were characterized by a combination of differential scanning calorimetry （DSC） and thermalgravimety （TG） on a multi-functional instrument. Confirmed by XRD and ESEM, the prepared platelets have mean diameters between 400 nm and 1 000 nm at 1 200℃. Most of them are aggregated and part of them through intergrowth. The platelets develop from the interface between glass and Al, and can form good moistening with the glass matrix. DSC/TG shows that α-Al2O3 formed by oxidation of Al, transforms into α-Al2O3and grow into the α-Al2O3 platelets owing to the formation of molten Al and the molten glass. On the other hand, part of the molten Al erodes into the glass and makes the deviation of the Na2O-CaO-SiO2 ternary system into Na2O-Al2O3 ternary system, resulting in the formation of NaAlSiO4.