低成本固废基无机陶瓷膜的反应制备与性能研究

发布时间：2018-01-25 22:01

本文关键词： 粉煤灰白云石钙长石堇青石陶瓷膜 Al(OH)_3 MoO_3 晶须状莫来石　出处：《华南理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于无机陶瓷膜材料具有优良的、有机高聚物膜所不及的性能,以及无机材料科学的发展,无机陶瓷膜的应用领域日益扩大,目前已经应用于环保、能源、食品、化工、医药等领域。但是无机陶瓷膜在应用中存在制备成本高、膜材质单一、高孔隙率与高机械强度难统一等问题。本论文工作以解决无机陶瓷膜制备成本高和改善孔隙率与机械强度统一的问题为目标,分别采用低成本原料和添加烧结助剂的方式,有效降低了多孔钙长石-堇青石基陶瓷膜和晶须状莫来石陶瓷膜的制备成本,而且明显提高了陶瓷膜的开孔隙率。具体的研究内容有以下两个方面:1.钙长石-堇青石基多孔陶瓷膜的制备研究钙长石(Ca O·Al2O3·2Si O2)和堇青石(2Mg O·2Al2O3·5Si O2)均是常用的无机陶瓷膜材料,具有热膨胀系数低、热导率低、介电常数小、抗热震性能好等优点,广泛用于陶瓷、耐火材料、电子等领域。本论文以廉价的工业废弃物粉煤灰(Si O2和Al2O3为主要成分)和天然矿物白云石(Ca Mg(CO3)2)为原料,通过原位反应烧结工艺制备了钙长石-堇青石基多孔陶瓷膜。同时,系统的研究了焙烧温度和白云石添加量对烧结行为、相组成、收缩率及体密度、开孔隙率、氮气和纯水通量、微结构和机械性能的影响。研究结果表明,添加了白云石28.43 wt.%的样品,二次致密化温度比未添加的提高了40 oC,表明白云石对粉煤灰的烧结有明显的抑制效果;在1100-1200 oC温度范围内,添加了白云石15 wt.%和28.43 wt.%的样品,在1150 oC以上才出现堇青石物相,而钙长石在1100 oC已生成;1150 oC时,当白云石的添加量增加至28.43 wt.%,开孔隙率可从25.23±0.47%提高到46.54±0.21%。继续增加白云石含量,由于多余的Mg O和Si O2形成Mg-Si二元玻璃相促进了陶瓷膜的致密,导致孔隙率下降。研究发现双轴弯曲强度与开孔隙率的关系呈指数衰减。通过SEM-EDS表征,进一步确定了堇青石和钙长石的存在以及两者的形貌。当添加量为28.43 wt.%、焙烧温度为1175 oC时,陶瓷膜的相组成为84%钙长石和16%堇青石,开孔隙率为38.8±0.8%,平均孔径为1.1μm,双轴弯曲强度为41±2 MPa,3.0 bar下氮气通量为3457.63 m3·m-2·h-1,纯水通量27.91 m3·m-2·h-1。总而言之,白云石不仅能在焙烧过程中释放大量CO2,同时可抑制粉煤灰的烧结,合成具有良好热性能的钙长石和堇青石。2.晶须状莫来石基多孔陶瓷膜的制备研究莫来石(3A12O3-2Si O2)作为一种经典陶瓷材料,其二次莫来石化温度一般在1200 oC。因此本论文工作秉承低成本、高性能的宗旨,以粉煤灰和Al(OH)3为原材料,Mo O3为添加剂,用反应烧结技术制备晶须状莫来石基多孔陶瓷膜,并系统地研究了其烧结动力学、相转变、收缩率、开孔隙率、孔径分布、N2通量、微结构以及机械性能。Mo O3的添加使莫来石基陶瓷膜的二次致密化温度由926 oC延长至1445 oC。结合XRD和SEM图,Mo O3通过在1100 oC形成低熔点的Ca Mo O4,进而促进低温液相的形成,降低二次莫来石化温度。同时Mo O3和Ca Mo O4的挥发为莫来石晶须的生长提供了充足的空间,促进了晶须的生长。陶瓷膜的开孔隙率随着Mo O3含量的增加而增加,最高达58%,孔径随之减小。氮气渗透通量与平均孔径的变化一致。在低温区(1300 oC以下),20 wt.%Mo O3添加量陶瓷膜的双轴弯曲强度高于未添加陶瓷膜的强度,这主要是因为晶须状莫来石形成的互锁结构对莫来石基陶瓷膜的强度起到了增强的作用。在同一强度值水平,20 wt.%Mo O3添加量的陶瓷膜拥有更高的开孔隙率。
[Abstract]:The inorganic ceramic membrane materials with excellent properties, organic polymer film than, as well as the development of inorganic materials science, application of inorganic ceramic membrane is growing, has been used in environmental protection, energy, food, chemical, medicine and other fields. But the inorganic ceramic membrane in the application of the existing high preparation cost, film single material, high porosity and high mechanical strength to uniform and other issues. The work of this paper to solve the inorganic ceramic membrane preparation and high porosity and uniform cost improve the mechanical strength of the problem as the goal, using low cost raw material and adding additives, effectively reduce the cost of preparation of porous anorthite - cordierite ceramics the membrane and whisker like mullite ceramic membrane, but also improves the porosity of ceramic membrane. The specific contents include the following two aspects: 1. calcium feldspar - cordierite ceramic membrane prepared by Kong Tao gedor Study of anorthite (Ca O Al2O3 2Si O2 (2Mg) and cordierite O - 2Al2O3 - 5Si O2) are inorganic ceramic membrane materials, has low thermal expansion coefficient, low thermal conductivity, low dielectric constant, good thermal shock resistance and other advantages, is widely used in ceramics, refractory materials, electronics etc. field. In this paper, the industrial waste fly ash cheap (Si O2 and Al2O3 as the main component of natural mineral dolomite (Ca) and Mg (CO3) 2) as raw material, through in-situ reaction sintering process for preparing calcium feldspar - cordierite porous ceramic membrane. At the same time, the system of calcination temperature and adding dolomite The amount of sintering behavior, phase composition, shrinkage and bulk density, open porosity, nitrogen and water flux, the effect of micro structure and mechanical properties. The results showed that adding dolomite 28.43 wt.% samples, two densification temperature than add increased 40 oC, showed that the dolomite of fly ash The sintering has obvious inhibiting effect; 1100-1200 in the temperature range of oC, adding 15 wt.% and 28.43 wt.% dolomite samples at 1150 oC above appeared cordierite phase, while calcium feldspar has been generated at 1100 oC; 1150 oC, when the amount of dolomite increased to 28.43 wt.%, open porosity can be improved from 25.23 + 0.47% to 46.54 + 0.21%. continue to increase the dolomite content due to the extra Mg, O and Si O2 Mg-Si two glass phase promoted dense ceramic membranes, resulting in decreased porosity. The study found that the biaxial flexural strength and porosity of exponential decay. Characterized by SEM-EDS, to further determine the cordierite and calcium the presence of feldspar and their morphology. When the adding amount is 28.43 wt.%, the calcination temperature is 1175 oC, which became the 84% group of calcium feldspar and 16% cordierite ceramic membrane, porosity was 38.8 + 0.8%, the average pore size is 1.1 m, biaxial bending Strength of 41 + 2 MPa, 3 bar nitrogen flux was 3457.63 m3 - m-2 - H-1, m3 - m-2 - 27.91 pure water flux of h-1. in dolomite can not only release a large amount of CO2 in the roasting process, at the same time can inhibit the sintering of fly ash, the synthesis has good thermal properties of calcium feldspar and cordierite stone.2. whisker mullite based porous ceramic membrane preparation of mullite (3A12O3-2Si O2) is a kind of classic ceramic material, the Mullitization temperature at 1200 oC. so this paper adhering to low cost, high performance purposes, using fly ash and Al (OH) 3 as raw materials, Mo O3 as additive. Preparation of mullite whisker based porous ceramic membrane by reaction sintering technology, and systematically studied the sintering kinetics, phase transition, shrinkage, porosity, pore size distribution, N2 flux, microstructure and mechanical properties of.Mo O3 to add two Mo density to stone based ceramic film The temperature was prolonged from 926 oC to 1445 oC. with XRD SEM and Mo O3, through the formation of low melting point Ca Mo O4 at 1100 oC, and then promote the formation of low temperature liquid phase, reduce the two Mullitization temperature. At the same time provide ample space for Mo O3 and Ca Mo O4 as the volatilization of mullite whiskers growth, promote whisker growth. Ceramic membrane porosity increases with the increase of Mo O3 content, up to 58%, pore size decreases. Change of nitrogen flux and average pore size. In the low temperature region (below 1300 oC), 20 wt.%Mo amount of O3 ceramic film biaxial flexural strength was higher than that of add the strength of ceramic membrane, this is mainly because of the formation of mullite whisker interlocking structure of mullite based ceramic film strength played a role in strengthening the level of value. At the same intensity, 20 wt.%Mo O3 added amount of ceramic membrane with higher porosity.

【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.1

【参考文献】