Abstract: Globular Al ₂O ₃ powders with diameter ( d ₅₀ ) of 5.82μm were prepared by spray-drying the solution of ammonium alum combined with pyrolysis process.SEM,XRD,DTA-TG,and Energy Spectrum were used to analyze the morphology and composition changes of powders obtained at different preparation stages.The results showed that the particles prepared by spray-drying were relatively coherent,then were dried,separated,dehydrated and shrunk after drying and pyrolysis processes.As a result,the diameter of powders decreased gradually,and the proportion of bigger particles significantly decreased.The sequence of the phase transition of ammonium alum was found to be NH ₄Al(SO ₄) ₂·12H ₂O→NH ₄Al(SO ₄) ₂→Al ₂(SO ₄) 3→ θ -Al ₂O ₃→ α -Al ₂O ₃ according to DTA-TG and XRD results.Sintered at 1370℃ for 2h, α -Al ₂O ₃ powders of high purity was obtained.

摘要： 以铵矾为原料 ,采用喷雾干燥结合煅烧热解工艺制得粒径 (d₅₀ )为 5 .82 μm的球形度良好的Al₂ O₃ 微粉 .利用DTA -TG、XRD、SEM及能谱分析研究了喷雾、干燥、热解 3个阶段所得粉体的形貌及组成的变化过程 .喷雾干燥制备的粉体 ,经进一步烘干、煅烧后 ,发生脱水、颗粒分离、热解和收缩 ,粒径不断减小 .煅烧热解所得Al₂ O₃ 微粉的晶型取决于热解温度和时间 ,1370℃煅烧 2h可获得结晶度良好的球形α -Al₂ O₃ 微粉