Oxidation of polycrystalline α-silicon carbide ceramic

Dean-Mo LIu*

*Corresponding author for this work

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

Oxidation behaviours and associated flexural strength of pressureless-sintered α-SiC ceramic, with Al 2 O 3 and Y 2 O 3 as sintering additives, were investigated in the temperature range of 1200-1350°C at 50°C intervals. The oxidation kinetics typically exhibited a parabolic behaviour which indicated a diffusion controlled mechanism with an activation energy ranging from 128 kJ/mol to 92 kJ/mol, decreasing monotonically with increasing additive content from 5 wt% to 20 wt%. The oxide scale was characterized in terms of microstructure and phase formation. The scale is essentially a composite structure consisting of pores, crystalline yttrium silicate and YAG phases, and amorphous silica. The flexural strength of the SiC decreases somewhat with oxidation due primarily to surface pit formation. The microstructure, particularly the initial surface morphology, of the SiC with higher additive content may also be considered as an important factor for strength behaviour after oxidation at elevated temperatures.

Original languageEnglish
Pages (from-to)425-436
Number of pages12
JournalCeramics International
Volume23
Issue number5
DOIs
StatePublished - 1 Jan 1997

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