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Journal of Advanced Ceramics

Keywords

ceramics, sintering, porosity, mechanical properties, permeability

Abstract

Silicon nitride foams with a hierarchical porous structure was formed by the combination of protein-based gelcasting, chemical vapor infiltration, and in-situ growth of silicon nitride nanowires. The porosity of the foams can be controlled at 76.3-83.8 vol% with an open porosity of 70.2-82.8 vol%. The pore size distribution was presented in three levels: < 2 μm (voids among grains and cross overlapping of silicon nitride nanowires (SNNWs)), 10-50 μm (cell windows), and >100 μm (cells). The resulted compressive strength of the porous bodies at room temperature can achieve up to 18.0±1.0 MPa (porosity = 76.3 vol%) while the corresponding retention rate at 800 ℃ was 58.3%. Gas permeability value was measured to be 5.16 (cm3·cm)/(cm2·s·kPa). The good strength, high permeability together with the pore structure in multiple scales enabled the foam materials for microparticle infiltration applications.

Publisher

Tsinghua University Press

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