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      Mechanical and dielectric properties of porous and wave-transparent Si 3N 4–Si 3N 4 composite ceramics fabricated by 3D printing combined with chemical vapor infiltration

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          Abstract

          Porous Si 3N 4–Si 3N 4 composite ceramics were fabricated by 3D printing combined with low-pressure chemical vapor infiltration (CVI). This technique could effectively improve the designability of porous Si3N4 ceramics and optimize the mechanical and dielectric properties. The effects of process parameters including the deposition time and heat treatment on the microstructure and properties of porous Si 3N 4–Si 3N 4 composite ceramics were studied. The study highlights following: When CVI processing time was increased from 0 to 12 h, the porosity decreased from 68.65% to 26.07% and the density increased from 0.99 to 2.02 g/cm 3. At the same time, the dielectric constant gradually increased from 1.72 to 3.60; however, the dielectric loss always remained less than 0.01, indicating the excellent electromagnetic (EM) wave-transparent performance of porous Si 3N 4–Si 3N 4 composite ceramics. The maximum flexural strength of 47±2 MPa was achieved when the deposition time attained 6 h. After heat treatment, the porosity increased from 26.07% to 36.02% and the dielectric constant got a slight increase from 3.60 to 3.70 with the dielectric loss still maintaining lower than 0.01. It has been demonstrated that the porous Si 3N 4–Si 3N 4 composite ceramics are a promising structural and EM wave-transparent material suitable for high temperature service.

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          Author and article information

          Journal
          J Adv Ceram
          Journal of Advanced Ceramics
          Tsinghua University Press and Springer-Verlag Berlin Heidelberg (USA )
          2227-8508
          2226-4108
          01 September 2019
          01 October 2019
          : 8
          : 3
          : 399-407
          Affiliations
          1Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, China
          Author notes
          *Corresponding author: Fang YE, E-mail: yefang511@ 123456nwpu.edu.cn
          Article
          s40145-019-0322-8
          10.1007/s40145-019-0322-8
          Copyright © The Author(s)

          This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See https://creativecommons.org/licenses/by/4.0/.

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