片状氧化铝的熔盐法制备关键参数

高径厚比片状Al₂O₃在高端珠光颜料片状基材应用方面潜力巨大，但是其制备技术为国外所垄断，开发片状Al₂O₃商用生产技术迫在眉睫。熔盐法是制备片状Al₂O₃的理想方法，目前尚无系统研究熔盐法关键工艺参数对片状Al₂O₃影响规律的报道。本文通过片状Al₂O₃的形成机理，系统研究了TiO₂添加剂、Na₃P₃O₉添加剂、煅烧温度和熔盐用量4种关键工艺参数对制备片状Al₂O₃的影响规律，并进一步优化制备工艺，提出最优工艺参数。利用扫描电子显微镜和X射线衍射仪分析Al₂O₃的形貌、粒度和物相。结果表明：采用熔融盐（Na₂SO₄-K₂SO₄）添加NaCO₃为凝胶剂，再加入质量分数分别为3.0%的Na₃P₃O₉和2.0%的TiO₂为添加剂，在煅烧温度为1200℃、保温时间5h时，所制得的六角片状Al₂O₃粉体具有优异的品质，其平均粒径约为4μm，厚度为50～200nm，径厚比为20～80。

Key parameters of preparing flake alumina by molten salt method

Flake alumina with high aspect ratio has attracted great attentions as a high-end pearlescent pigment flake substrate. However, the preparation technology is controlled by other countries so that it is essential to develop new preparation method for flake alumina. The molten salt method is an ideal method for the flake alumina production. However, the systematic research of the key parameters of the method has not been reported. Based on the formation mechanism of flake alumina, this article systematically studies the influence of TiO₂ additives, Na₃P₃O₉ additives, calcination temperatures and molten salt dosages on the preparation of flake alumina. The scanning electron microscope and X-ray diffractometer are used to analyze the morphology, particle size and phase composition of flake Al₂O₃. The results show that hexagonal flake alumina can be obtained with molten salt (Na₂SO₄-K₂SO₄) and NaCO₃ as gelling agent, 3.0% Na₃P₃O₉ and 2.0% TiO₂ as additives after calcination at 1200℃ for 5h. The final product possesses the average particle size of 4μm, the thickness of 50—200nm and the aspect ratio of 20—80.