【作者】 杨晔；

【导师】 吴玉程； 李云；

【作者基本信息】 合肥工业大学 ， 材料加工工程， 2002， 硕士

【摘要】 本研究以NH₄Al（SO₄）₂和NH₄HCO₃为原料，采用沉淀法制备了氧化铝前驱体碳酸铝铵（AACH）。研究发现，通过直接在1150℃煅烧该前驱体不能获得无团聚、粒径较小的α-Al₂O₃纳米粉体。接着，就分别研究在前驱体中加入或掺杂Q-Al₂O₃粉体籽晶、氧化铝胶体籽晶、TiO₂溶胶、硝酸铵以及高能球磨前驱体等一系列因素对α相变温度、最终产物微结构、相变过程等的影响。研究表明，上述几种因素均能降低α相变温度，然而温度的降幅以及对最终粉体微结构的影响是不同的，其中，影响最大的是氧化铝胶体籽晶的添加。研究结果显示，含有20wt％胶体籽晶的前驱体AJS20在1000℃左右煅烧就可获得平均粒径为70nm、无团聚的纳米α-Al₂O₃粉体；而含有2wt％胶体籽晶的前驱体AJS2在1100℃即可获得粒径在100nm左右、几乎单颗粒分散、有少量“树枝状”微结构的纳米α-Al₂O₃粉体。本文还简要地给出了以上各影响因素的作用机制。 此外，还利用粒度分析来表征纳米α-Al₂O₃粉体在水性体系中的分散情况，并找出最佳的分散工艺。结果表明，PAA在碱性条件下是α-Al₂O₃粉体的最佳分散剂。更多还原

【Abstract】 In this research, ammonium aluminum carbonate hydroxide （AACH）, the precursor of α -AL₂O₃, was synthesized by precipitation method using NH₄AL（SO₄）₂ and NH₄HCO₃ as raw materials. The research firstly showed that the α -AL₂O₃ powder obtained by directly calcining the AACH at 1150℃ owned a bad microstructure. Then, we utilized the additives of α -AL₂O₃ powder seeding, alumina sol seeding, TiO₂-sol , ammonium nitrate , and high-energy ball milling on the precursors to investigate these factors’ influences on the α transformation temperature, the microstructure of as-received nano-sized α -AL₂O₃ powders and transformation sequences. This research indicated all these factors can reduce the α transformation temperature, but the range of reduction and the influence on the microstructure of powders were not identical. Among these factors, alumina sol seeding was the most effective. AJS20, the precursor contained 20wt% alunina sol seeding, was calcined at around 1000℃ to get free-aggregation nano-sized a -AlaOs powders with a median particle size of 70nm. And, calcining AJS2, the precursor contained 2wt% alumina sol seeding, at HOO’C , we get a -AlaOs nano-sized powders with a particle size of lOOnm and good dispersion by TEM . This paper also gives the proper mechanisms of these factors’ influences on the transformation to alpha phase.In addition to, the dispersion state of nano-sized a -A^Os powder in water was characterized by analyzing the particle size distribution and calculating the average size. We also used this method to search the best dispersion agents. The result shows that PAA is the best dispersion agent for the a -AhOs powder at basic system.更多还原