论文总字数：22238字

摘 要

多孔碳化硅陶瓷在催化、尾气处理、废液处理等领域具有广阔的应用前景，莫来石由于具有强度高、耐酸碱性能好等优点，使得以莫来石为结合相制备的多孔SiC陶瓷具有优异的性能。以氧化铝和二氧化硅粉体为原料制备莫来石结合碳化硅陶瓷的传统方法存在结合相分布均匀性差的问题。因此，本课题以水溶性硝酸铝和硅溶胶为原料，对制备莫来石结合SiC多孔陶瓷具有重要意义。

本课题以粒径60μm的SiC为原料，硝酸铝和硅溶胶为结合相原料，采用固相烧结和溶胶凝胶法制备碳化硅多孔陶瓷，系统地研究莫来石含量、烧成温度、保温时间、石墨添加量等对多孔SiC陶瓷密度、显气孔率、抗弯强度、物相组成、颗粒表面形貌等结果。研究表明，以硝酸铝和硅溶胶混合可以使莫来石相更加均匀的附着在SiC颗粒上；莫来石作为结合相可以起到一定增强作用但是烧成温度和保温时间超过一定值后强度增强作用反而会被抵消而呈强度下降趋势；气孔率随莫来石含量的增加大体呈现一个上升的趋势，密度随莫来石含量的增加大体呈下降趋势。样条气孔率随石墨添加量的增加而明显增加，而抗弯强度和密度则随其显著下降。本课题所研究的多孔陶瓷样条组中莫来石含量为25%在1450℃下保温1h烧成，抗弯强度可达7.3MPa、气孔率达44.7%。

关键词：碳化硅 多孔陶瓷 莫来石 抗弯强度 气孔率

Preparation and Properties of Mullite-bonded Silicon Carbide Porous Ceramics

ABSTRACT

Porous silicon carbide ceramics have broad application prospects in catalysis, tail gas treatment, waste liquid treatment and other fields. Because of its high strength and good acid and alkali resistance, mullite-bonded porous SiC ceramics have excellent properties. The traditional method of preparing mullite bonded silicon carbide ceramics from alumina and silica powder has the problem of poor uniformity of bonding phase distribution. Therefore, it is of great significance to prepare mullite bonded SiC porous ceramics by mixing sol-gel method with water-soluble aluminum nitrate and silica sol as raw materials.

In this paper, mullite-bonded SiC porous ceramics were studied by solid-phase sintering and sol-gel method using SiC with sizes of 60μm and aluminium nitrate and silica sol as binder raw materials. The effects of mullite content, sintering temperature, holding time and pore-forming agent addition on the density, porosity, flexural strength, phase composition and surface morphology of porous SiC ceramics were systematically studied. The results show that the mixture of aluminium nitrate and silica sol can make mullite phase more uniformly adhere to SiC particles; mullite as a bonding phase can play a certain role in strengthening, but when the sintering temperature and holding time exceed a certain value, the strength enhancement will be counteracted and the strength will decrease; The porosity increased with the increase of mullite content, and the density generally decreased with the increase of mullite content.The porosity of the spline increases significantly with the addition of graphite, while the flexural strength and density decrease significantly. In the porous ceramic spline group studied in this paper, the bending strength is 7.3 MPa and the porosity is 44.7% when it is sintered at 1450℃ for 1 hour with 25% mullite content .

Key Words: SiC; Porous ceramics; Mullite; Bending strength; Porosity

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1引言 1

1.2多孔陶瓷的主要制备方法及特点 1

1.2.1颗粒堆积法 1

1.2.2模板复制法 2

1.2.3牺牲模板法 3

1.2.4直接发泡法 4

1.3不同类型结合相的碳化硅多孔陶瓷 4

1.3.1莫来石结合碳化硅多孔陶瓷 5

1.3.2堇青石结合碳化硅多孔陶瓷 6

1.3.3氧化硅结合碳化硅多孔陶瓷 6

1.3.4氮化硅结合碳化硅多孔陶瓷 7

1.3.5 SiOC结合碳化硅多孔陶瓷 7

1.4 主要研究内容 7

第二章 实验方法与过程 8

2.1 实验原料与器件 8

2.1.1实验原料 8

2.1.2实验器件 8

2.2 实验流程 8

2.3 性能测试和表征 11

2.3.1密度和显气孔率测试 11

2.3.2抗弯强度测试 12

2.3.3 物相分析 12

2.3.4微观形貌分析 12

第三章 莫来石结合碳化硅多孔陶瓷性能研究 13

3.1 粉末微观形貌分析 13

3.2 烧成温度的分析与确定 13

3.3 烧成温度对碳化硅多孔陶瓷性能的影响 14

3.3.1 烧成温度对体积密度和显气孔率的影响规律 14

3.3.2 烧成温度对抗弯强度的影响规律 16

3.4 保温时间对碳化硅多孔陶瓷性能的影响 17

3.4.1 保温时间对体积密度和显气孔率的影响规律 17

3.4.2 保温时间对抗弯强度的影响规律 18

3.5 莫来石含量对碳化硅多孔陶瓷性能的影响 19

3.5.1 莫来石含量对体积密度和显气孔率的影响规律 19

3.5.2 莫来石含量对抗弯强度的影响规律 20

3.6 物相分析 21

3.7 石墨含量对碳化硅多孔陶瓷性能的影响 23

第四章 结论与展望 25

4.1 结论 25

4.2 展望 25

参考文献 26

致谢 29

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