(中南大學(xué) 冶金科學(xué)與工程學(xué)院, 長沙 410083)
摘 要: 以Al2(SO4)3與(NH4)2CO3為原料， 采用液相沉淀法制備出前驅(qū)物碳酸鋁銨（AACH）， 并煅燒得到超細(xì)Al2O3粉末。研究加料次序、 pH值、 加料方式以及表面活性劑等因素對(duì)反應(yīng)產(chǎn)物的影響， 同時(shí)分析前驅(qū)物AACH的高溫相變過程。 利用X射線衍射（XRD）、 掃描電鏡（SEM）、 比表面積（BET）、 熱重/差示掃描法（DTA/TGA）等多種分析檢測技術(shù)對(duì)粉體的性能進(jìn)行表征。結(jié)果表明： 只有將硫酸鋁溶液霧化加入到碳酸銨溶液中， 添加適量PEG1000作為分散劑， 控制反應(yīng)終點(diǎn)pH值為8以上， 才能制備出粒度分布均勻、 分散性能優(yōu)異的前驅(qū)物AACH； 而AACH的高溫相變過程為： AACH→AlOOH→Al2O3（無定型）→γ-Al2O3→θ-Al2O3→α-Al2O3；合成的AACH于1 200 ℃煅燒2 h， 能得到粒度分布均勻、 形貌為球形且分散性良好的α-Al2O3粉體。
關(guān)鍵字: 超細(xì)α-Al2O3； 碳酸鋁銨； 熱分解； 相變； 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
