熔盐法低温制备片状氧化铝的工艺研究

Study on preparation of flake alumina by molten-salt method at low temperature

目前使用熔盐法制备片状Al_(2)O_(3)的煅烧温度高达1200℃,通过降低煅烧温度,在较低温度下制备出高径厚比的片状Al_(2)O_(3),符合节能减排的要求。本文将使用Al(OH)_(3)在550℃下煅烧得到的非晶态Al_(2)O_(3)作为前驱体,利用熔盐法,分别使用Na Cl-KCl、Na_(2)SO_(4)-K_(2)SO_(4)混合熔盐,通过加入15wt%粒径为200nm的Al_(2)O_(3)晶种,在900℃下合成片状Al_(2)O_(3)。通过考察煅烧时间、熔盐、添加剂对合成片状Al_(2)O_(3)形貌及厚径比的影响,发现在煅烧时间为6h、加入比为4∶1的Na Cl-KCl混合熔盐、加入3wt%的TiO_(2)和3wt%的Na_(3)PO_(4)制备出了粒径均匀(约为5μm)、形貌规则的六边形状的片状Al_(2)O_(3)。

At present,the calcination temperature of flake alumina prepared by molten salt method is as high as 1200℃,and the high diameter to thickness ratio of flake alumina prepared at lower temperature meets the requirements of energy saving and emission reduction.In this paper,amorphous alumina obtained from Al(OH)_(3)calcined at 550℃ was used as precursor,by using molten salt method,NaCl-KCl and Na_(2)SO_(4)-K_(2)SO_(4) mixed molten salt were respectively used to synthesize flake alumina at 900℃ by adding 15wt%alumina seed with a particle size of 200 nm.By comparing the effects of calcination time,molten salt and additives on the morphology and thickness to diameter ratio of synthesized flake alumina,it is found that hexagonal flake alumina with uniform particle size and regular morphology was prepared at a calcination time of 6h,adding NaCl-KCl mixed molten salt with a ratio of 4:1,and adding 3wt%TiO_(2) and 3wt%sodium phosphate.