采用引入晶种的水热合成法制备α-Al_2O_3纳米粉

PREPARATION OF NANO-SIZE α-Al_2O_3 POWDERS BY SEEDING HYDROTHERMAL SYNTHESIZING METHOD

采用水热合成法制备α -Al2 O3 微粉时 ,水热处理温度需要在大于 45 0℃下才能进行 ,这在工艺上难以实现 ,但引入与α -Al2 O3 具有等结构的晶种 ,可以增加成核密度 ,提高成核速率 ,降低成核的活化能 ,从而降低相变温度 ,使水热处理温度降低到 2 0 0℃以下 ,并使粉末的煅烧温度降到 930℃ .实验结果表明 ,采用添加 4%(inmass)α -Al2 O3 晶种的水热合成法制备的α-Al2 O3 为粒度分布均匀、颗粒近似球形的纳米级 ( 6 8nm)的粉末 .

The hydrothermal treating temperature is more than 450 ℃ in the preparation of α-Al 2O 3 ultrafine powders by hydrothermal synthesis method, which is difficult to achieve. The addition of crystal seeds increases the nucleation rate, reduces the nucleation activation energy and therefore reduces the phase transformation temperature, and reduces hydrothermal treating temperature to less than 200 ℃. The α-Al 2O 3 powders synthesized with 4%(in mass) α-Al 2O 3 crystal seeds is nano_size powders (68 nm) with uniform size and ball_like shape.