高孔隙率SiC陶瓷载体的氮气催化燃烧合成机理

Developing new technology with low energy consumption for the fabrication of photocatalytic support is one of the key factors to accelerate the large application of photocatalysis technique in the field of cleaning indoor air.This project aims to develop a “replicating organic foams shaping-combustion synthesis in nitrogen atmosphere” combination technology to prepare high porosity SiC ceramic support for photocatalytic applications. The bottleneck of the existing fabrication techniques with long term high temperature heat treatment will be broken by make full use of the strong exothermic reaction of Si-C-N system，and high porosity SiC ceramic support can be obtained without further sintering. The evolution characteristics of the macro kinetics, phase compositions and microstructures of combustion reaction of Si-C system in nitrogen atmosphere with high porosity will be studied and revealed. The size stability mechanism of the high porous structure in combustion reaction will be clarified. SiC ceramic support with porosity ≥90%, compressive strength≥1MPa and pore size ≥1mm will be obtained via process optimization..Benefiting from this project, a new fabrication technology with low energy consumption will be developed for the high porosity SiC ceramic support, technical support and theoretical guidance will also be provided for the fabrication of key materials to dealing with the indoor air pollution of our country.

发展光催化剂载体材料的低能耗制备新技术，是推进光催化技术在室内空气污染治理中规模应用的关键之一。本项目旨在采用“有机泡沫浸渍成型-氮气催化燃烧合成”组合技术制备光催化用高孔隙率SiC陶瓷载体，充分利用Si-C-N体系反应强放热的特征，突破现有制备技术需要长周期高温热处理的瓶颈，实现高孔隙率SiC陶瓷载体的无烧结制备。研究揭示高孔隙率条件下Si-C体系氮气催化燃烧反应的宏观动力学特征、物相组成及微观结构演变规律，并阐明多孔结构的尺寸稳定机制。通过优化工艺，获得孔隙率≥90%、抗压强度≥1MPa、网孔尺寸≥1mm的SiC陶瓷载体材料。.通过本项目研究，有望发展一种低能耗的高孔隙SiC陶瓷制备新技术，为我国室内空气污染治理关键材料的制备提供重要技术和理论支撑。

发展了一种高孔隙SiC陶瓷材料的“有机泡沫浸渍成型-氮气催化燃烧合成”组合制备技术。研究揭示了Si-N-C的三元燃烧反应机理，氮气作为催化剂参与燃烧反应促进Si的气化，随后与固相C反应生成SiC。通过调控C源尺寸以及添加聚四氟乙烯添加剂，实现了SiC的限域生成调控。通过聚氨酯泡沫浸渍成型制备了不同网孔尺寸的Si-C多孔坯体，充分利用Si-N体系反应强放热的特征，采用埋粉燃烧合成的方法，实现了高孔隙SiC陶瓷的快速制备，其孔隙率≥90%、抗压强度≥1MPa、网孔尺寸≥1mm。此外，研究揭示了Si-N-O三元燃烧反应的气相氮化机理，建立了基于不同粒度原料反应的接触模型；发展了一种快速、低成本制备高强度Si3N4多孔陶瓷的燃烧合成工艺，阐明了燃烧过程多孔坯体的尺寸稳定机制，制备出孔隙率49%、抗弯强度151MPa、具有良好机加工性能的Si3N4多孔陶瓷，在催化剂载体、水处理、烟气过滤等领域展现出潜在应用前景。