Oxidation behavior of different La2O3-content modified SiC ceramic at 1700 °C

Wei Xie, Qiangang Fu, Chunyu Cheng, Ningning Yan

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Silicon carbide (SiC) ceramic specimens doped with different contents of La2O3 were prepared by hot pressing process to investigate the influence of La2O3 content on their anti-oxidation performance at 1700 °C. The result of the isothermal oxidation test reveals that La2O3-doped SiC ceramic showed better anti-oxidation performance than pure SiC ceramic, and the anti-oxidation performance of La2O3-doped SiC ceramic decreased as the content of La2O3 increased. Mulliken population analysis based on first-principle calculation indicates that the strength of Si–O bond was enhanced by adding a small amount of La dopant (~5 wt%) into SiO2, which is favorable to the thermal stability of the oxide scales. The coexistence of SiO2 and La2Si2O7 under a certain ratio makes the glass layer have proper viscosity to form a compact and smooth protective layer, thus leading to a better anti-oxidation performance at 1700 °C. However, the SiC ceramic doped with excessive La2O3 (10–15 wt%) showed poor anti-oxidation performance owing to the defective glass layer and the destruction of SiO2 structure. This work is beneficial to select which La2O3 content is suitable for the anti-oxidation SiC ceramic coating at 1700 °C.

Original languageEnglish
Pages (from-to)11560-11567
Number of pages8
JournalCeramics International
Volume47
Issue number8
DOIs
StatePublished - 15 Apr 2021

Keywords

  • First-principle calculation
  • LaO content
  • Oxidation
  • SiC

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