Effect of pre-oxidation on the microstructure, mechanical and dielectric properties of highly porous silicon nitride ceramics

Rubing Zhang*, Daining Fang, Xiangmeng Chen, Yongmao Pei

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

Highly porous Si 3N 4 ceramics have been fabricated via freeze casting and sintering. The as-sintered samples were pre-oxidized at 1200-1400 °C for 15 min. The effect of pre-oxidation temperature on the microstructure, flexural strength, and dielectric properties of porous Si 3N 4 ceramics were investigated. As the pre-oxidation temperature increased from 1200 °C to 1400 °C, firstly, the flexural strength of the pre-oxidized specimens remained almost constant at 1200 °C, and then decreased to 14.2 MPa at 1300 °C, but finally increased to 25.6 MPa at 1400 °C, while the dielectric constant decreased gradually over the frequencies ranging from 8.2 GHz to 12.4 GHz. This simple process allows porous Si 3N 4 ceramics to have ultra-low dielectric constant and moderate strength, which will be feasible in broadband radome applications at high temperatures.

Original languageEnglish
Pages (from-to)6021-6026
Number of pages6
JournalCeramics International
Volume38
Issue number7
DOIs
Publication statusPublished - Sept 2012
Externally publishedYes

Keywords

  • B. Porosity
  • C. Dielectric properties
  • C. Mechanical properties
  • D. Si N

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