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在探讨了乙醇铝水解形成氢氧化铝凝胶的机理和凝胶在干燥过程中的团聚机理后,改变了以往的醇铝水解方式,实现晶核的同步生长,得到均匀一致的凝胶颗粒。无水乙醇对疑胶的洗涤。有助于改善凝胶的团聚性,初步认为其作用机理在于,乙醇取代了胶粒间的部分配位水或AlO_6八面体链间的部分架桥羟基,起到了空间位阻稳定作用,减少了粒子之间的连接性。本论文首次以胶体稳定理论为基础,以 Hamaker常数为依据,选择庚烷、辛烷和 R-75等有机溶剂作水解体系,取代传统的水体系,制备出了蓬松的纤维状或球形γ-AlOOH粉末。 研究了分散剂S对制备的γ-AlOOH凝胶的形貌和分散性的影响规律和作用机理,发现它对煅烧态粉末的性质影响不大。研究了超细纤维状γ-AlOOH 粉末团聚体在煅烧过程中物理性质的变化规律,获得纯度大于99.97％的分散球形γ-和α-Al_2O_3粉末,其平均粒径分别为50和90nm。 研究了在制备γ-AlOOH粉末过程中,加入的盐酸对锻烧态粉末性质的影响。控制盐酸的加入量,可制得纤维状γ-Al_O_3粉末,长径比为 5～15,直径约为 2nm。当盐酸与乙醇铝的摩尔比从0.0增加到0.04时,粉末成球温度从1200℃降到500℃;在高酸量时,形成的AlCl_3能促进γ-AlOOH脱水时的自粉碎效应,生成无定形的超细Al_2O_3粉末,粒径为 3～5nm,在500℃?
After discussing the mechanism of the formation of aluminum hydroxide gel by aluminum hydrate and the agglomeration mechanism of the gel during the drying process, the former aluminum-aluminum hydrolysis method was changed to realize the synchronous growth of crystal nucleus to obtain uniform gel particles. Anhydrous ethanol on the suspect gum washing. Which can help to improve the agglomeration of the gel. The mechanism is that ethanol replaces part of coordination water or part of bridging hydroxyl groups between AlO_6 octahedral chains with ethanol, which stabilizes steric hindrance and reduces Particle connectivity. Based on the theory of colloid stability and based on the Hamaker constant, this paper chose organic solvents such as heptane, octane and R-75 as the hydrolysis system to replace the traditional water system and prepared fluffy fibrous or spherical γ- AlOOH powder. The influence and mechanism of dispersant S on the morphology and dispersity of γ-AlOOH gel were investigated. It was found that it had little effect on the properties of calcined powder. The variation of the physical properties of the ultrafine fibrous γ-AlOOH powder agglomerates during calcination was studied. The spherical γ- and α-Al 2 O 3 powders with the purity of more than 99.97% were obtained. Their average particle sizes were 50 and 90 nm, respectively. The effect of added hydrochloric acid on the properties of calcined powders during the preparation of γ-AlOOH powders was investigated. Controlling the amount of hydrochloric acid added, a fibrous γ-Al_O_3 powder can be obtained, with an aspect ratio of 5-15 and a diameter of about 2 nm. When the molar ratio of hydrochloric acid to aluminum alcoholate increased from 0.0 to 0.04, the temperature of powder ball decreased from 1200 ℃ to 500 ℃. At high acid amount, the formation of AlCl 3 promoted the self-comminution effect of γ-AlOOH dehydration, Shape the fine Al_2O_3 powder, particle size of 3 ~ 5nm, at 500 ℃?