【作者】 孟卫松；

【导师】 朱伯铨；

【作者基本信息】 武汉科技大学 ， 材料学， 2004， 硕士

【摘要】 本文采用直接沉淀法、均匀沉淀法和前驱体热解法等三种方法制备了纳米氧化铝粉体。在直接沉淀法制备纳米氧化铝粉体的研制过程中，采用了价格相对较为低廉的氯化铝为原料，以氨水为沉淀剂，对反应物的浓度、溶液的pH值、陈化时间等工艺参数进行了研究。结果表明，采用该种方法得到的颗粒尺寸大，粒度分布范围宽，粉体性能不够理想。在均匀沉淀法制备纳米氧化铝粉体的研制过程中，以氯化铝和硝酸铝为原料，六次甲基四胺为沉淀剂，对反应物的浓度、反应物配比、反应温度和反应时间等工艺参数进行了研究。结果表明，以硝酸铝为原料、反应物浓度为2.0mol／L、50℃×30min水浴加热后能制得透明稳定的氢氧化铝凝胶，凝胶经冷冻干燥并于1150℃×60min煅烧后能制得粒度为80～120nm、呈无规则形状的纳米α-Al₂O₃颗粒。该方法制备纳米氧化铝粉体具有工艺简单、成本低、纯度高、能够大量生产、设备制造简单和工艺流程短等优点，是一种具有极大潜力的纳米粉体制备方法。在前驱体热解法制备纳米氧化铝粉体的研制过程中，研究了以硫酸铝铵和碳酸氢铵为原料，采用化学沉淀法制备尺寸均一、颗粒细小、分散的碳酸铝铵沉淀先驱体的工艺。研究表明，反应物的混合方式、滴定速度、反应物配比以及反应体系的pH值等因素对前驱体的形成有非常大的影响。对两种不同的前驱体产物分别采用超临界干燥和冷冻干燥，并在不同的温度下煅烧，用XRD、DTA—TG、TEM、BET等测试方法对粉体性能进行了表征。结果表明，将0.2mol／L的硫酸铝铵溶液以2～3ml／min的速度滴加到2.0mol／L的碳酸氢铵溶液中，控制反应体系的pH值为8.5～10.0，碳酸氢铵对硫酸铝铵的配比过剩系数为1.20～1.40，可获得性能良好的前驱体碳酸铝铵沉淀（NH₄AlO（OH）HCO₃）。前驱体经超临界干燥、1200℃×60min煅烧后能得到团聚程度小、长度为100～200nm、宽度为5～10nm的呈纤维状的纳米α-Al₂O₃粉体。更多还原

【Abstract】 Adopting three methods (direct precipitation method,homogeneous precipitataion method and precursor pyrogenation method), nano-Al2O3 powder has been prepared in the present paper. In the process of preparing nano-Al2O3 powder by direct precipitation method, relatively cheap AlCl3 was used as raw material, NH3 H2O as precipitator, the process parameters including concentration of reactants,pH values of solutions and aging time were studied. Experimental results show that powder size, size distribution of granularity and the properties of nano-Al2O3 powder prepared in this way were not very well.In the process of preparing nano-Al2O3 powder by homogeneous precipitataion method, using AlCl3 and Al(NO3)3 as raw materials, hexametny lenetetramie as precipitator, process parameters including concentration of reactants, proportion of reactants, reaction temperature and reaction time were studied.It was indicated that steady and transparent A1(OH)3 geltum can be produced by using A1(NO3)3 as raw material under the condition of reactants concentration of 2.0mol/L and reaction temperature of 50 C in a water bath for 30mins, then 80~120nm and irregular sized nano- -Al2O3 powder can be prepared through calcining geltum at 1150C for 1h. This is a potential way to prepare nano-powder because of its characteristics such as relative simple technology, high purity, high efficiency and relative simple facilities requirement.In the process of preparing nano-Al2O3 powder by chemistry precipitation method, the technology of uniform sized NH4A1O(OH)HCO3 precursory preparation was studied. Research shows that technical factors including mixing mode of reactants , titration speed , proportion of reactants and pH value of solutions etc have a great influence on the formation of precursor. Adopting supercritical drying and feeze drying technology, these two kinds of precursor were pretreated, sintered at different temperature. XRD,DTA?TG,TEM,BET techniques were used to characterize the nano-Al2O3 powder, the results show that drop NH4A10(OH)HCO3 solution whose concentration is 0.2mol/L into NEUHCO3 solution whose concentration is 2 mol/L with the speed of 2 ~3ml/min, controlling the solution pH value is about 8.5 ~ 10.0, and the excess-ratio of matching NH4HCO3 to NH4Al(SO4) 2 is about 1.20~1.40, can get good-nature precursor of NH4AlO(OH)HCO3. through supercritical dried, 1200 C 60 min calcined, low agglomeration fiber-like nano- -Al2O3 power with the length of 100~200nm and the wideth of 5~ 10nm can be prepared.更多还原