Oxidation of Polymer-Derived HfSiCNO up to 1600 degree C

Oxidation behavior of HfSiCNO ceramics for Hf/Si ratio of 0.09 at 1400 degree C-1600 degree C in ambient air is reported. Quantitative X-ray analysis of oxidized powders shows crystalli-zation of the amorphous phase into tetragonal hafnia, hafnon, and cristobalite (carbides, seen in inert atmosphere...

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Bibliographic Details
Published inJournal of the American Ceramic Society Vol. 96; no. 4; pp. 1278 - 1284
Main Authors Terauds, Kalvis, Marshall, David B, Raj, Rishi
Format Journal Article
LanguageEnglish
Published 01.04.2013
Subjects
Bundles
Ceramics
Dip coatings
Hafnium oxide
Nanostructure
Oxidation
Oxides
Silicon carbide
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Summary:Oxidation behavior of HfSiCNO ceramics for Hf/Si ratio of 0.09 at 1400 degree C-1600 degree C in ambient air is reported. Quantitative X-ray analysis of oxidized powders shows crystalli-zation of the amorphous phase into tetragonal hafnia, hafnon, and cristobalite (carbides, seen in inert atmosphere heat treatments are absent). Cross-sectional SEM shows the oxide overgrowth on the particles to contain precipitates of hafnia/hafnon, while the interior of the particles is decorated with nanoscale grains of hafnia in a necklace-like formation. The oxidation kinetics of these materials, determined both from weight-change measurements and from direct observation of oxide overgrowth, are shown to be comparable to the oxidation of SiC single crystals. Oxidation of SiC-SiC minicomposites (straight fiber bundles infiltrated with a SiC matrix), coated with thin films of HfSiCNO prepared by dip-coating was studied. The overgrowth thicknesses for oxidation time of 1000 h at 1600 degree C are compared for uncoated, SiCN(O)-coated, and HfSiCNO-coated minicomposites.
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ISSN:0002-7820
1551-2916
DOI:10.1111/jace.12239