Study On Preparation And Properties Of SiC Ceramic Composite Filtration Membrane Materials

Using two methods of the preparation of SiC Ceramic Composite Filtration Membrane materials, studied their properties and compared Properties the thesis contents:section one is experiment about Various compositions of ceramic fiber slurry were prepared to discuss the influence of ceramic fiber layer on Filter pressure drop and structure of SiC filtration membrane, effect of bonding agents on porosity and pore size distribution of filtration membrane, when bonding agentss at15wt%, effect of pore-forming agent on porosity of filtration membrane. Tape casting method was used to prepare the filtration membrane covering on the SiC green body. And XRD and SEM were performed to examine the phase constitution and morphology. The porosity and pore size distribution of filtration membrane were tested by Archimedes method and bubble point method respectively. The results show that, there is a SiO2diffraction peak with the2θ=22°in the filtration membrane sample sintered at1300℃for3h. When the composition of ceramic fiber slurry in mass ratio of aluminum silicate fibers:mullite fibers:CMC:water is1:X(X=0,0.5,1.0,1.):1.5:65, and0≤X≤1.0, the SiC ceramic filtration membrane becomes more uniform and complete increasing content of mullite fibers. Meanwhile, ceramic fiber layer can prevent the filtration membrane falling into the gaps of SiC support body and Filter pressure drop along with the decrease. While X>1.0(X=1.5), excess mullite fibers lead a bad adhesive quality of SiC support body and filtration membrane and filter pressure drop increases. X=1.0is an appropriate content of mullite fibers, and the whole complex SiC ceramic filtration system has a perfect structure. However, if there is not any ceramic fiber layer, the filtration membrane drops into the gaps of SiC support body easily which has an impact on the structures and properties of complex SiC ceramic filtration membrane material.When the content of bonding agents increased from5wt%to25%, however, the porosity dropped from46%to29%and average pore size decreased from11.916μm to4.017μm. The porosity was changed from41%to60%with the amount of bonding agents was fixed at15%but the content of pore-forming agents became from5wt%to25%. filter pressure drop minimumSilicon carbide ceramic composite filter membrane materials were prepared by dry pressure molding and synchronous sintering process at sintering temperature of1300℃for3h. And research the influence of on the molding pressure structure of SiC filtration membrane,effect of particle size on porosity, average pore size and filter pressure drop of filtration membrane, SEM was performed to examine the morphology, The porosity, average pore size and filter pressure drop of filtration membrane were tested by Archimedes method, bubble point method and filter pressure drop instrument. It is demonstrated that while the molding pressure (F) varied from1MPa to10MPa, the filter membrane material achieved preferable morphology and best performance when F equals to5MPa. Under this modeling pressure, while silicon carbide particle size increased from1to23μm, the pore ratio decreased from48.0%to36.2%and the average pore size increased from0.35μm to9.4μm, while the air gas velocity changed from0to0.112m/s. when the velocity and pressure are stable, the filter pressure drop reduced as the silicon carbide particle size more enlargement, the filter pressure drop increase as pressure build up when the velocity and silicon carbide particle size are stable.Silicon carbide ceramic composite filter membrane materials were preparation by dry pressing molding and synchronization sintering,and tape casting. Preparation methods to compare, The pore distribution more uniform and the structure relatively flat of the filter membrane, the preparation process simpler and energy consumption smaller, but the filter membrane porosity become smaller and the pressure become bigger.