Study On Preparation, Microstructure And Properties Of Composite SiC Ceramics

Based on the preparation of high strength and high porosity of the sic porous ceramic membrane support and low filtration pressure drop of the filtration membrane as the research target. Adopts silicon carbide as the main material, and adding ceramic binder, graphite and activated carbon as the pore-forming agent, layered coating technology on preparation of silicon carbide porous ceramic support body, and using mold molding in the powder forming technology. With this method, the preparation of support structure has good pore connectivity. We had studied the influence of ceramic binder content, and particle size to the bending strength of support body and the filter performance.There is an optimal value of body bending strength about the ceramic binder content on silicon carbide porous ceramic support, on the optimal value, silicon carbide porous ceramic support body has the higher bending strength and higher porosity. Different body molding pressure, optimal value ceramic binder content is different. When the molding pressure is10MPa and15MPa, the optimal value of vitrified bond is10wt%and5wt%respectively. As the powder particle size smaller, the bending strength of porous ceramics and the filter pressure drop has trend of increasing, and the porosity also has a tendency to increase. The decrease of the silicon carbide particle size is beneficial to increase bending strength of silicon carbide porous ceramic support.so the silicon carbide particle size is determined for165-200μm is appropriate.It has used the method of uniform membranes ejection to prepare the transition layer and precision controlled layer. The ceramic fiber transition layer can effectively prevent the sic of small pore size to enter the support body. It reduced the actual thickness of membranes, and then reduced the filter pressure drop, and increased the service life of the material. It also can make the accuracy control layer of the coating film is more uniform and complete.It has introduced the study of the structure and properties of porous ceramics with the silicon carbide micro powder, and tested the shrinkage rate, bending strength and filter pressure drop. By the study we have found that with the decrease of the silicon carbide particle size, the silicon carbide porous ceramic shrink significantly,the bending strength is larger, and the filter pressure drop is relatively small.