Synergistic promotion of dielectric and thermomechanical properties of porous Si_(3)N_(4)ceramics by a dual-solvent template method  

作　　者：Yuanyuan Liu Zhilin Tian Liya Zheng Bin Li 

机构地区：[1]School of Materials,Shenzhen Campus of Sun Yat-sen University,Shenzhen 518107,China

出　　处：《Journal of Advanced Ceramics》2024年第10期1622-1634,共13页先进陶瓷（英文）

基　　金：supported by the National Natural Science Foundation of China(Grant No.52202078);the Leading Talent Project of the National Special Support Program(Grant No.2022WRLJ003);the Guangdong Basic and Applied Basic Research Foundation for Distinguished Young Scholars(Grant No.2021B1515020083);the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2021A1515110293 and 2022A1515012201).

摘　　要：Porous Si_(3)N_(4)ceramics are promising high-temperature wave transparent materials for use as radomes or antenna windows in hypersonic aircraft.However,a trade-off between the dielectric and thermomechanical properties is still challenging.Therefore,tailoring the microstructure and properties of porous Si_(3)N_(4)is highly important.In this work,porous Si_(3)N_(4)ceramics with uniform and fine structures were obtained via dual-solvent templating combined with the freeze-casting method.The as-prepared porous Si_(3)N_(4)ceramic,with 56%porosity,possesses high mechanical properties,with flexural strength and compressive strength values of 95±14.8 and 132±4.5 MPa,respectively.The uniform spherical pore structure improved the mechanical properties,and the rod-shaped Si_(3)N_(4)grains facilitated crack deflection.The decreased pore size effectively blocks phonon transport,leading to a low thermal conductivity of only 4.2 W/(K·m).Moreover,the porous Si_(3)N_(4)ceramic maintains a small dielectric constant of 3.3,and the dielectric loss is stable between 1.0×10^(-3)-4.0×10^(-3),which guarantees its potential application in high-temperature wave-transparent components.These results significantly advanced the development of high-performance wave-transparent materials used in hypersonic aircraft.

关 键 词：Si_(3)N_(4) porous ceramics freeze-casting wave-transparent material dual solvent 

分 类 号：TQ174.1[化学工程—陶瓷工业]