Abstract
Porous Si3N4 ceramics were prepared by aqueous gelcasting using Si3N4 poly-hollow microspheres (PHMs) as pore-forming agent. The effects of solid loading of Si3N4 slurry and Si3N4 PHM content on the properties of porous Si3N4 ceramics were investigated. Only β-Si3N4 phase is observed in porous Si3N4 ceramics, and Si3N4 PHMs distribute uniformly both in Si3N4 green samples and porous Si3N4 ceramics. Results show that solid loading of Si3N4 slurry and Si3N4 PHM content could considerably influence the properties of porous Si3N4 ceramics. With the increase of solid loading of Si3N4 slurry (decrease of Si3N4 PHM content), the distributing state of Si3N4 PHMs changes from contacting with each other to just embedding in the matrix, thus their porosity decreases, while their shrinkage, flexural strength, and fracture toughness increase.
Highlights
IntroductionPorous Si3N4 ceramics are one of the most promising structural and functional materials in the engineering applications (such as high-temperature gas/liquid filters, thermal insulators, catalyst carriers, antenna windows, and separation membranes, etc.), which is attributed to their unique properties such as low density, high porosity, acceptable dielectric properties, high specific surface area, high hardness, high fracture toughness, and so on [1,2,3,4]
Porous Si3N4 ceramics are one of the most promising structural and functional materials in the engineering applications, which is attributed to their unique properties such as low density, high porosity, acceptable dielectric properties, high specific surface area, high hardness, high fracture toughness, and so on [1,2,3,4]
The Si3N4 poly-hollow microspheres (PHMs) were used as pore-forming agent to prepare porous Si3N4 ceramics via aqueous gelcasting
Summary
Porous Si3N4 ceramics are one of the most promising structural and functional materials in the engineering applications (such as high-temperature gas/liquid filters, thermal insulators, catalyst carriers, antenna windows, and separation membranes, etc.), which is attributed to their unique properties such as low density, high porosity, acceptable dielectric properties, high specific surface area, high hardness, high fracture toughness, and so on [1,2,3,4]. There are lots of micro-pores in ceramic PHMs, whose inner structures are completely different from those of the conventional hollow spheres. These ceramic PHMs are fabricated through a special route without any sacrificial cores, which combines the particle-stabilized foams and centrifugal atomizing technology together [20,21]. In order to increase porosity of porous Si3N4 ceramics, different contents of Si3N4 PHMs were added into Si3N4 slurry with different solid loadings, and the effects of solid loading of Si3N4 slurry and Si3N4 PHM content on the properties of porous Si3N4 ceramics were investigated
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