(中南大学 冶金科学与工程学院, 长沙 410083)
摘 要: 以Al2(SO4)3与(NH4)2CO3为原料， 采用液相沉淀法制备出前驱物碳酸铝铵（AACH）， 并煅烧得到超细Al2O3粉末。研究加料次序、 pH值、 加料方式以及表面活性剂等因素对反应产物的影响， 同时分析前驱物AACH的高温相变过程。 利用X射线衍射（XRD）、 扫描电镜（SEM）、 比表面积（BET）、 热重/差示扫描法（DTA/TGA）等多种分析检测技术对粉体的性能进行表征。结果表明： 只有将硫酸铝溶液雾化加入到碳酸铵溶液中， 添加适量PEG1000作为分散剂， 控制反应终点pH值为8以上， 才能制备出粒度分布均匀、 分散性能优异的前驱物AACH； 而AACH的高温相变过程为： AACH→AlOOH→Al2O3（无定型）→γ-Al2O3→θ-Al2O3→α-Al2O3；合成的AACH于1 200 ℃煅烧2 h， 能得到粒度分布均匀、 形貌为球形且分散性良好的α-Al2O3粉体。
关键字: 超细α-Al2O3； 碳酸铝铵； 热分解； 相变； 分散
thermal decomposition of AACH
（School of Metallurgical Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: Ammonium aluminum carbonate hydroxide (AACH) was synthesized as the precursor by the precipitation reaction of aluminum sulfate and ammonium carbonate. Then the precursor was calcined to get α-Al2O3 powder. The effect factors of reaction on preparing AACH, such as the order and methods of adding materials, pH value and surfactant, were discussed, and the thermal decomposition reaction of AACH was also analyzed. The structural properties of powders were characterized by XRD, SEM, DTA/TGA and BET measurements. The results show that the AACH particles with uniform particle size and well-distributed can be synthesized with aluminum sulfate atomizing into ammonium carbonate, adding suitable amounts of PEG1000 as dispersant, and controlling the pH value over 8. The phase transformation of AACH in calcination process is as: AACH→AlOOH→amorphous Al2O3→γ-Al2O3→θ-Al2O3→α-Al2O3. The ultrafine α-Al2O3 with uniform particle size and in spherical shape and well dispersed were obtained by AACH calcined at 1 200 ℃ for 2 h.
Key words: ultrafine α-Al2O3; ammonium aluminum carbonate hydroxide (AACH); thermal decomposition; phase transformation; dispersion
