摘 要

随着高温工业的快速发展，能源短缺问题加剧，推动了新型耐高温隔热材料的研究。多孔陶瓷具有优良的化学稳定性，抗热冲击性能好，且密度小，气孔率较高，比表面积大，热导率低，是新型耐火材料的理想选择，已经在冶金、航天、能源等多个领域广泛应用。溶胶-凝胶工艺作为一种新兴的制备工艺，可以制备出具有纳米级孔径的多孔陶瓷，并且可以调控孔隙的分布。与传统陶瓷制备工艺相比，溶胶-凝胶法显著降低了烧成温度，能够比较容易地进行多种离子的掺杂，有利于制备复合材料。

氧化铝基多孔陶瓷具有良好的化学稳定性、抗热冲击性、高孔隙率等优点，使其在化工、节能环保、催化剂载体等方面都具有广泛的应用前景。采用溶胶-凝胶工艺，可以制得孔径在纳米级的微孔氧化铝基多孔陶瓷，但是想实现对其孔隙结构和分布的精确控制还难以实现。本实验采用溶胶-凝胶法，在铝溶胶中掺入不同浓度的镁离子，意图改变胶体粒子的双电层结构，从而改变胶团的组装取向，最终形成气孔结构不同的氧化铝基多孔陶瓷。实验中简要得到了以下几个结论：

（1）水解温度会影响铝凝胶粉料和Al₂O₃基陶瓷粉料的微观结构和晶相组成：水解温度低，孔隙大；常温水解，陶瓷粉料晶相为Al₂MgO₄，60℃水解且Mg² /Al³ 浓度比适宜时，陶瓷粉料晶相为Al_2.4Mg_0.4O₄；

（2）Mg² 浓度会影响Al₂O₃基多孔陶瓷的微观形貌：Mg² 掺入量增加，凝胶粉料的孔隙尺寸越来越小；Mg² 掺量增加，陶瓷粉料表面产生更多更细的纤维状晶须，晶须相互缠绕使得气孔孔径减小，气孔率随之发生变化。

关键词：溶胶-凝胶法，多孔陶瓷，氧化铝陶瓷

Abstract

With the rapid development of the high temperature industry, the problem of energy shortage become severe, and this situation drive the research of new thermal insulation material. Porous ceramics possess excellent chemical stability and heat endurance, have low density, high porosity, large specific surface area and small heat conductivity. As an ideal refractory matter, porous ceramics have been widely used in metallurgy, spaceflight, energy and so many fields. Sol-Gel technology is an new-type of preparation method for porous ceramics. In usage of this technology, we can produce porous ceramics, which has nanoscale bore diameter and equally distribute pores. Compare with the traditional ceramics techniques, the Sol-Gel technology decreases the firing temperature markedly, and is conducive to the adulteration of multiple ions, so it was available in the production of composite materials especially.

Alumina oxide porous ceramics possess favorable chemistry stability, heat resistance and high porosity. All these advantage make alumina oxide porous ceramics have extensive application prospect in many fields, such as chemical engineering, energy conservation and environment protection, and catalyst carrier. In the usage of Sol-Gel technology, we can obtain micro pore alumina oxide porous ceramics, which has nanoscale bore diameter. But it is hard to realize the accuracy control to the structure and distribution of pores. This experiment use Sol-Gel technology, and we mix different concentrations magnesium ion to alumina sol. Because we want to change the structure of double electrode layer of colloid particles, thus change the assemble direction micelle. In the end, we can obtain alumina oxide porous ceramics with different pore structures.

We can obtain two conclusions as follows:1.Hydrolyzing temperature will affect microstructure and phase composition of alumina gel powder and Al₂O₃ ceramic powder. The hydrolyzing temperature becomes low，the pore becomes larger. Hydrolyze in room temperature, the ceramics phase is Al₂MgO₄, hydrolyze in 60℃, and the concentration ratio of Mg² /Al³ is proper, the ceramics phase is Al_2.4Mg_0.4O₄. 2.The concentration of Mg² will affect the microphotography of Al₂O₃ ceramics.Increase the concentration, the pore size of gel powder gets smaller, and the surface of ceramics powder generates more and thinner fibrous whisker. Crystal whisker convolve with each other makes the pore size decrease, and change the porosity finally.

Keyword: Sol-Gel technology, porous ceramics, Al₂O₃ ceramics

目录

中文摘要 I

Abstract II

第1章 绪 论 1

1.1 背景概述 1

1.2 多孔陶瓷的制备工艺 1

1.3 溶胶-凝胶法 3

1.3.1 溶胶-凝胶法的基本原理 3

1.3.2 溶胶-凝胶法的基本过程 5

1.3.3 溶胶-凝胶法的特点 6

1.4 双电层理论 7

1.5 本课题的立题意义和研究内容 7

第2章 实验原料、仪器及表征测试方法 9

2.1 引言 9

2.2 实验原材料和仪器 9

2.2.1 实验所用原材料 9

2.2.2 实验所用仪器 10

2.3 Sol-Gel法制备Al₂O₃基陶瓷孔结构材料工艺 10

2.3.1 Al₂O₃基溶胶凝胶的合成步骤 10

2.3.2 具体实验配方记录 11

2.3.3 对干凝胶的高温热处理 12

2.4 结构与形貌的表征 12

2.4.1 物相组成分析 12

2.4.2 显微结构分析 12

第3章 Al₂O₃基陶瓷孔结构材料的结构形貌 13

3.1 Al₂O₃基陶瓷粉末的微观结构与形貌 13

3.1.1 不同水解温度下Al₂O₃基陶瓷粉末的微观形貌 13

3.1.2 不同Mg² 浓度下Al₂O₃基陶瓷粉末的微观形貌 15

3.2 X-射线衍射分析 17

3.2.1 700℃处理时的XRD检测 17

3.2.2 1000℃处理时的XRD检测 18

第4章 结论和展望 22

参考文献 23

致谢 24

第1章 绪 论

1.1 背景概述

随着工业化的快速发展以及社会的不断进步，能源短缺问题日益凸显，在国内外引起了越来越多的关注。尤其是我国，庞大的人口基数和亟待高速发展的经济决定了能源消耗总量居高不下的现状，能源紧张问题严重阻碍了国民经济的发展和人民生活水平的提高，引起政府及相关科研单位对新能源的开发和节能方面的高度重视。而陶瓷孔结构材料孔隙率高，密度和热传导系数比较小，热阻大，能够耐高温且隔热效果良好。由于它能够有效提高能源的利用效率，达到节能的目的，因此吸引了许多研究者潜心于新型陶瓷隔热材料的研发，多种新型隔热耐高温陶瓷材料相继问世，陶瓷孔结构材料就是其中性能优良的一种。