【作者】 吴铭敏；

【导师】 周竹发；

【作者基本信息】 苏州大学 ， 材料学， 2009， 硕士

【摘要】 采用高岭土为原料制备纳米氧化铝具有成本低廉,可大幅度提高高岭土的产品附加值,增加经济效益等优点。采用正交试验法研究了酸溶分解高岭土时,高岭土的粒径、活化条件(煅烧温度、保温时间)及酸浸条件(浓度、温度、时间、反应比)等对Al3+浸取率的影响;采用碱法提纯酸浸液,研究了碱液浓度、反应比、温度、时间等对降低杂质(Fe3+、Ti4+)含量的影响;以提纯后浸取液为原料,采用勃姆石凝胶法和碳酸铝铵热解法制备纳米氧化铝粉体,研究了反应物浓度、浓度比、pH、分散剂、反应温度、反应时间、煅烧温度等对粉体粒径、松装密度、形貌、晶型、纯度及获得率的影响。采用TG-DTA、XRD、SEM、TEM、电感耦合等离子体原子发射光谱仪、傅立叶红外光谱仪、显微共焦拉曼光谱仪、表面电位粒径仪、激光粒度分析仪等测试方法和设备对前驱体和粉体性能进行了表征。通过大量实验及分析研究,得出如下结论:(1)苏州高岭土700℃左右煅烧后由晶相转变为非晶相,有利于提高与酸的反应活性。但温度过高,石英相增多,反应活性降低;(2)酸浸时,酸的浓度、反应时间、反应温度等对浸取率的影响较大,较低的酸浓度,较长的反应时间和较高的反应温度有利于浸取率的提高;(3)强碱处理浸取液,较高的碱液浓度、用量和反应温度能有效降低杂质离子含量;(4)碳酸铝铵热解法比薄姆石凝胶法更易获得粒径小、分散性好,纯度高的纳米氧化铝粉体。实验结果表明:高岭土煅烧活化后与20wt%的盐酸95-100℃反应3h,铝的浸取率可达~93.83%;2.5mol·L-1的NaOH处理浸取液,[Fe3+]降低了98.19mol%,[Ti4+]降低了98.30mol%;当[AlCl3]=1.5mol·L-1,[NH4HCO3]/[AlCl3]=10/3,pH=9时制备的AACH沉淀1150℃煅烧后得到松装密度0.36g·cm-3、纯度98.21%、粒径10-20nm的α-Al2O3粉体。更多还原

【Abstract】 Using Kaolin as a raw material to prepare nanometer alumina powder can reduce the cost and improve the Kaolin’s attachment value and economic efficiency in a large scale. The orthogonal testing method has been used to study some preparing factors on the dipping reaction of Kaolin with acid, such as the particle size of Kaolin, Kaolin calcined temperature, holding time, concentration of HCl, reaction temperature, reaction time, molar ratio of reactants etc. Adopting alkaline process, the concentration of impurity, such as Fe3+ and Ti4+, has been reduced. In the process, the concentrate of NaOH, molar ration of Al3+ to NaOH, reaction temperature, reaction time have been studied. Nanometer alumina powder had been acquired from boehmite xerogel and ammonium aluminum carbonate hydroxide (AACH). The influence of the concentration of reactants, ratio of reactants’ concentration, pH, kinds and addition amount of dispersant agents, reaction temperature, reaction time and calcined temperature of precursor on the particle size, packing density, morphology, crystal form and purity have been discussed. The precursor and nanometer Al2O3 powder were characterized by TG-DTA, XRD, SEM, TEM, ICP-AES, FT-IR, Raman, Superficial Electric Potential Particle Size Meter, Laser Granularity Analysis, et al.According to large numbers of experiments, some conclusions have been drew: (1) After calcining at 700℃, the reactivity of the Kaolin has been improved owing to the crystal form of Kaolin transformed from crystalling phase to the amorphous phase. But the hyperpyrexia could make the amount of the quartz increase, the reactivity reduced; (2) The higher leaching rate could be achieved when Kaolin reacted within acid of a lower concentration at a higher temperature for a longer time; (3) The concentration of Fe3+ and Ti4+ in the leaching fluid could be more reduced by reacting within more amount of higher concentration of NaOH solution at a higher temperature; (4) The smaller average particle size, better dispersivity, higher purity nanometerα-Al2O3 could be achieved by calcining AACH.The results show that the leaching rate of ~93.83% could be achieved when Kaolin calcined at 700℃for 2h, reacted within HCl of 20wt% at 95-100℃for 3h. After the reaction of leaching fluid with 2.5mol·L-1 NaOH, the concentration of Fe3+ in the filtrate has be reduced by 98.19mol% as well as Ti4+ by 98.30mol%. Particle size of 10-20nm, packing density of 0.36g·cm-3 nanometerα-Al2O3 with purity of 98.21% was prepared by calcining AACH synthesized from 1.5mol·L-1 AlCl3 react with NH3HCO3 at pH=9, [NH4HCO3]/[AlCl3]=10/3 and calcined temperature 1150℃.更多还原