The effect of CaO-TiO2 on the sintering properties of SiC matrix composites

Bo Pan, Xiao Yun Li, Tai Qiu, Jian Yang

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Abstract

6H-SiC and α-Al2O3 powders that as raw materials were mixed as mass ratio of 7:3 with CaO and TiO2 as sintering additives. The green body was preoxidated for 1 h at 1200℃ after being pressed. Sic matrix composites were prepared by pressureless sintering for 1 h in hydrogen atmosphere. The effects of CaO-TiO2 content and sintering temperature on the sintering properties and phasecomposition were investigated. The results suggested that: withthe increase of sintering temperature form 1400 to 1 500℃, the compactness improves significantly. At the sintering temperature of 1 450℃, the samples were basically compact. And the sample's apparent porosity decreased to 0.15% with m(CaO-TiO2) of 10% added. The reaction of CaO-TiO2 cristobalite, with α-Al2O3, had generated CaAl2Si2O8 at 1200℃, and generated CaTiSiO5 after 1 300℃, which promote the 6H-SiC further oxidation. In the process of sintering, CaAl2Si2O8 formed liquid glass phase which deposits mullite and promoted sample's densification. At 1 500℃, the main crystal phase of the composite material was 6H-SiC, mullite.

Original languageEnglish
Pages (from-to)21068-21071
Number of pages4
JournalGongneng Cailiao/Journal of Functional Materials
Volume45
Issue number21
DOIs
StatePublished - 15 Nov 2014

Keywords

  • Apparent porosity
  • Hydrogen
  • Pressureless sintering
  • SiC

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