Fabrication and Characterization of Porous Silicon Nitride Bodies through Starch Consolidation Casting and Pressureless Sintering


Department of Metallurgy and Materials Science, Iran University of Science and Technology, Tehran, Iran


Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casting. In this method, starch plays both pore-forming and consolidating roles. The effect of starch content on the viscosity of Si3N4/starch slurry was investigated in this research. Rotational Rheometer was used to study the rheological behavior of Si3N4/starch slurry. Green samples with 5 to 10MPa flexural strength were shaped by casting slurries in a nonporous mold and held at 80°C for 120min. Afterward the samples burned-out and sintered at 1650°C for 4h in an air furnace under a nitride powder bed condition. Thermal behavior, phase evolution, and microstructure of sintered samples were characterized through Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The XRD results showed that was the main phase in the sintered samples. The  phase content was as much as 90wt% in the sintered samples. Finally, a porous silicon nitride sample was successfully produced with 44vol% open porosity and Flexural strength of 108.9MPa through the starch consolidation casting method. 


Main Subjects


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