【作者】 杨阳；

【导师】 陈代荣； 焦秀玲；

【作者基本信息】 山东大学 ， 纳米材料化学， 2013， 硕士

【摘要】 本论文主要探讨了利用两种不同的前驱体,即勃姆石加入晶种和碳酸铝铵,经过高温煅烧合成超细α-Al2O3粉体。通过对前驱体以及最终α-Al2O3粉体进行X-射线衍射、热重、透射电镜、扫描电镜以及激光粒度分布表征,分析了各实验参数、工艺流程对所得前驱体及最终粉体的影响,探讨了制备条件与其微观结构和性质之间的关系,从而为制备性能优异的超细氧化铝粉体提供理论和实验依据。1.勃姆石引入晶种法制备高纯超细α-Al2O3粉体通过在水热合成的勃姆石前驱体中引入拟薄水铝石溶胶晶种的方法制备了α-Al2O3粉体,并采用XRD、TEM、SEM、激光粒度分布等分析测试手段表征了产物的物相组成、形貌、粒径大小、粒径分布,研究了晶种加入量对产物形貌及粒度的影响。TG-DSC结果表明,勃姆石前驱体要在1250℃的高温下煅烧才能得至α-Al2O3物相,并且产物为烧结的蠕虫状结构,分散性较差,但是拟薄水铝石在1150℃就可发生α相变,当向勃姆石中加入少量拟薄水铝石作为晶种,可使勃姆石前驱体的α相变温度由1250℃降低到1175℃,并改善了最终α-Al2O3粉体的微观形貌,由蠕虫状变为无团聚的分散颗粒,所制备的α-Al2O3粉体纯度高,平均粒径为250nm左右,粒径分布窄,分散性好；随着晶种加入量的增大,α-Al2O3粉体的平均粒径未发生明显变化,但粒径分布明显变窄。2.碳酸铝铵热解法制备高纯超细α-Al2O3粉体通过硫酸铝铵与碳酸氢铵的沉淀反应首先制备得到碳酸铝铵前驱体,再经高温热分解得到了α-Al2O3粉体,采用XRD、TEM、SEM、激光粒度分布等分析测试手段对前驱体及最终产物进行了表征,研究了沉淀反应参数、实验工艺对前驱体形貌及粒径的影响,以及机械球磨前驱体对最终α-Al2O3粉体的影响。结果表明,在室温条件下,采用同时滴加两种原料液的方式,在合适的原料摩尔比及底液体积的最优制备条件,能得到分散性好无团聚的近长方体碳酸铝铵聚集体前驱体；通过改变原料溶液的滴加速度,能得到不同粒径大小的前驱体颗粒；对前驱体进行机械球磨预处理再进行高温煅烧,能明显降低前驱物的α相变温度,并改善最终α-Al2O3粉体的微观形貌,使产物由大小不均匀的蠕虫状颗粒转变为分散的类球形颗粒；对不同粒径大小的前驱体球磨相同时间后再进行煅烧,可以得到不同粒径大小的α-Al2O3粉体,在一定程度上做到了粒径可控的α-Al2O3粉体的制备。更多还原

【Abstract】 In this paper, fine-grained a-alumina powders with high-purity were synthesized using boehmite or ammonium alumina carbonate hydroxide (AACH) as precursors after the calcinations process. The obtained precursors and final α-Al2O3powders were characterized in detail by XRD, SEM, TEM, TG-DSC, and particle size distribution analysis. The effect of experiment parameters, process technology and calcinations process on the properties of precursor samples and final α-Al2O3powder was investigated. The relationship between the preparation parameters and the microstructures of the materials are established, which might provide a theoretical basis for the synthesis of precursors and α-Al2O3with good performance.1. Preparation of fine-grained a-alumina powders with high-purity from boehmite with seeding additionFine-grained a-alumina powder was prepared from boehmite sol with pseudo-boehmite as seed. The effect of the seed on the formation temperature and the particulate properties of α-Al2O3was investigated using XRD, SEM, TEM, TG-DSC and particle size distribution analysis. TG-DSC and XRD results showed that the phase transformation from prepared boehmite to α-Al2O3begins to occur at-1250℃with vermicular agglomerated particles obtained, but the phase transition for as-prepared pseudo-boehmite could take place at～1150℃. When a small amount of pseudo-boehmite were added into boehmite sol, during calcinations α-Al2O3particles formed in situ from pseudo-boehmite at lower temperature can play a role as seed nucleation, which then induce the phase transformation from boehmite precursor to α-Al2O3and obviously lowered the tranformation temperature. The experimental results showed that the obtained α-Al2O3powders had an average particle size of-250nm with high purity, good dispersity and narrow particle size distribution. With the increasing of the seed amount, no remarkable change was observed in the average particle size of α-Al2O3particles, but the particle size distribution became narrower.2. Preparation of fine-grained a-alumina powders with high-purity by thermal decomposition of AACHFine-grained α-alumina powder was prepared by thermal decomposition of ammonium aluminum carbonate hydroxide (AACH), a new precursor obtained via the precipitation reaction between ammonium aluminum sulphate (NH4Al(SO4)2) and ammonium hydrogen carbonate (NH4HCO3). The precursor and the calcined product were characterized by XRD, SEM, TEM, TG-DSC and particle size distribution analysis. The effect of experiment parameters, process technology and mechanical milling pre-treatment on the properties of precursor and final α-Al2O3product was investigated. The results showed that less-agglomerated, well-discrete and cuboid-like AACH precursor can be successfully synthesized in the optimal technical condition; AACH sample with different particle size was obtained by varying the titration rate of the raw material solutions; mechanical milling AACH precursor drastically lowered the a-alumina transition temperature and spherical-like α-Al2O3particles with less-agglomerated rather than vermicular agglomerated particles were obtained at lower calcination temperature; α-Al2O3powder with controllable diameter was finally successfully synthesized by calcining different-sized AACH precursor.更多还原