滑石/高岭土体系堇青石多孔结构形成机理及性能研究

Formation Mechanism and Properties of Porous Structure of Cordierite in Talc/Kaolin System

柴油机颗粒捕集器对于烟气中污染物颗粒的截留效果与陶瓷基体的孔径分布及孔隙率密切相关,对于堇青石陶瓷多孔结构的有效调控,是提高柴油机颗粒捕集器过滤效率的关键。通过研究滑石/高岭土的质量配比对堇青石多孔结构的影响,阐明了堇青石基体中孔隙的形成机理及演变过程。滑石和高岭土的分解过程及产物结晶过程引起的体积收缩效应是堇青石基体中孔隙形成的基础。在液相烧结作用下,层叠的片状粉体之间的间隙先融合形成弥散分布的小孔,接着小孔互相连接形成线状孔隙,最终融合为边缘光滑的大孔。同时,还研究了滑石/高岭土的质量配比对堇青石多孔陶瓷热导率、收缩率及三点弯曲强度的影响,通过对比,选用中值孔径为0.15μm、孔隙率为18.41%的0.1TKMS配方作为优选配方,所得样品热导率为2.06 W·m^(−1)·K^(−1)、三点弯曲强度高达51.83 MPa。通过调控原料配比,热导率最高提升了63.5%;收缩率最大减小了83.9%;三点弯曲强度最高提升了239.2%。

Diesel particulate traps can be used to intercept pollutant particles in flue gas and this interception effect is closely related to the pore size distribution and porosity of the ceramic matrix.Effectively managing the porous structure of cordierite ceramics is crucial for optimizing their DPF filtration efficiency.The impact of talc/kaolin mass ratios on the porous structure of cordierite was studied,elucidating the pore formation mechanism and evolution within the cordierite matrix.The decomposition process of talc,coupled with volume shrinkage during crystallization,serves as the foundation for pore formation in the cordierite matrix.Through liquid-phase sintering,the gaps between the laminated flake powders began to merge,forming a diffuse distribution of small holes.Then,the small pores were connected to form linear pores,which eventually merged into large pores with smooth edges.Simultaneously,the effects of talc/kaolin mass ratios on the thermal conductivity,shrinkage,and three-point bending strength of cordierite porous ceramics were explored.The 0.1TKMS exhibited optimal performances,with a value pore size of 0.15μm and a porosity of 18.41%.The optimized sample had a thermal conductivity of 2.06 W·m^(−1)·K^(−1)and a three-point bending strength of as high as 51.83 MPa.The thermal conductivity was increased by 63.5%,the maximum volume shrinkage rate was decreased by 83.9%and the maximum three-point bending strength was increased by 239.2%.