Scale characterisation of an oxidised (Hf,Ti)C-SiC ultra-high temperature ceramic matrix composite

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  • University of the Witwatersrand


A hybrid carbide ultra-high temperature ceramics matrix [(Hf,Ti)C-SiC] reinforced with BN-coated carbon fibres was fabricated and tested for surface oxidation resistance. The UHTC composite showed an average mass ablation rate of 0.0014 g/s after exposure to a high heat flux (∼17 MW/cm2) oxyacetylene flame test for 30 s above 2500 °C. The cross-sectional profile of the oxides scale formed was characterised and analysed. The scale was multicomponent; consisting of oxides of Hf, Ti and Si, as well as HfTiO4 and HfSiO4, which underwent phase separation and immiscibility. Multiple glassy bubbles formed on the scale surface due to the impediment of escaping gases by the glassy layer on the outer scale. The largest pores in the scale and surface bubbles that resisted rupture were the dominant features of the outermost phase-separated layer. Phase separation in the scale top layer improves the resistance to scale rupture.

Bibliographic note

Funding Information: This work was funded by the DST-NRF Centre of Excellence in Strong Materials (CoE-SM) . Opinions expressed and conclusions arrived at, are those of the authors and are not necessarily to be attributed to the CoE-SM.


Original languageEnglish
Pages (from-to)167-175
Number of pages9
JournalJournal of the European Ceramic Society
Issue number1
Early online date26 Aug 2020
Publication statusPublished - Jan 2021


  • Ceramic matrix composite, Oxidation scale, Oxyacetylene torch, Phase immiscibility, UHTC