多孔碳化硅陶瓷表面改性及其烟气过滤性能研究

发布时间：2018-01-10 01:19

本文关键词：多孔碳化硅陶瓷表面改性及其烟气过滤性能研究　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来雾霾天气成为人们关注的热点,而霾的核心物质是沉积在空气中的灰,烟尘等颗粒物,且极易吸入人体肺部产生危害。而柴油车产生的尾气主要以碳颗粒为主,是造成雾霾天气的一个主要成因。目前柴油车尾气处理方式主要依靠壁流式过滤器捕集颗粒物,而柴油车运行工况复杂,排放尾气温度较高,因此要求过滤壁具有耐高温,抗氧化,耐腐蚀等优良特性,而多孔碳化硅陶瓷因其优异独特的性能成了过滤材料的热门选择,并成为材料学领域的研究热点。其原料来源广泛,成本低廉,传统制备方法多样。本文利用木材的天然多孔结构,以榉木为模板采用液态硅浸渍的独特方法制备生物形态多孔碳化硅陶瓷,所得产物性能优异,具有良好的孔隙结构,在节能减排方面具有很大优势,但其在过滤超细颗粒时仍存在一些局限,当生物形态碳化硅过滤纳米级别颗粒物时,高的孔隙度可以有效地捕集微小颗粒物,但同时造成通透性减小,发动机排气背压升高,减小其寿命。因此制备出通透性良好且捕集效率高的多孔碳化硅将成为我们重点解决的问题。故而本研究通过模拟人的呼吸系统,仿生设计合成类似支气管表层的纤毛状微观结构,采用熔盐法和溶胶-凝胶法对多孔碳化硅陶瓷表面进行改性处理,分别利用熔盐化学反应和溶胶-凝胶制备工艺在碳化硅陶瓷孔隙中生长出莫来石和硼酸铝晶须,通过各种表征手段发现良好的晶须形貌生长在碳化硅基质上。为了测试改性材料的过滤性能,又搭建了柴油燃烧烟气过滤测试平台,保持通入的空气流量恒定,控制温度小幅度变化,分别测试空白颗粒物浓度、柴油燃烧烟气颗粒物浓度、烟气经过碳化硅陶瓷过滤的颗粒物浓度、经过碳化硅/莫来石的颗粒物浓度,将对照实验数据进行对比分析,获得过滤性能与微观结构之间的构效关系,柴油烟气经过改性后的碳化硅/莫来石材料过滤,测得的颗粒物浓度值明显降低,表明改性后制备的莫来石晶须结构的多孔陶瓷对颗粒物的捕集过滤性能强于改性之前,也为后期的改性实验做出了引导。
[Abstract]:In recent years, haze weather has become the focus of attention, and the core matter of haze is ash, smoke and other particulates deposited in the air. And easily inhaled the human lungs to cause harm, and diesel vehicle emissions are mainly carbon particles. At present, diesel vehicle exhaust gas treatment mainly depends on wall flow filter to capture particulate matter, while diesel vehicle operating condition is complex, exhaust gas temperature is higher. Therefore, filtration wall is required to have excellent properties such as high temperature resistance, oxidation resistance, corrosion resistance and so on. Porous silicon carbide ceramics have become the hot choice of filtration materials because of its excellent and unique properties. It has become a research hotspot in the field of materials science. Its raw materials are widely available, the cost is low, and the traditional preparation methods are various. In this paper, the natural porous structure of wood is used. Biologically porous silicon carbide ceramics were prepared by liquid silicon impregnation with beech as template. The obtained products have excellent properties and good pore structure, and have great advantages in energy saving and emission reduction. However, there are still some limitations in the filtration of ultrafine particles. When nano-sized particles are filtered by biomorphic silicon carbide, high porosity can effectively capture micro-particles, but at the same time, reduce the permeability. Therefore, the preparation of porous silicon carbide with good permeability and high trapping efficiency will be a key problem for us to solve. Therefore, this study simulates the respiratory system of human beings. The ciliated microstructure similar to the bronchial surface was synthesized by bionic design. The porous silicon carbide ceramic surface was modified by molten salt method and sol-gel method. Mullite and aluminum borate whiskers were grown in the pores of silicon carbide ceramics by molten salt chemical reaction and sol-gel preparation respectively. In order to test the filtration performance of the modified materials, a diesel combustion flue gas filtration test platform was set up to keep the air flow rate constant. The concentration of blank particles, the concentration of particulate matter from diesel combustion smoke, the concentration of particulate matter filtered by sic ceramic, and the concentration of particulate matter through silicon carbide / mullite were measured respectively by controlling the small change of temperature. By comparing and analyzing the experimental data, the structure-activity relationship between filtration performance and microstructure was obtained. After modified sic / mullite filter, the measured concentration of particulate matter was obviously decreased. The results showed that the porous ceramics with mullite whisker structure prepared after modification were better than those before modification in the trapping and filtration of particulate matter, and also provided guidance for the later modification experiment.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X701

【参考文献】