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SiC Depletion in ZrB 2 –30 vol% SiC at Ultrahigh Temperatures
Author(s) -
Shugart Kathleen,
Opila Elizabeth
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13519
Subject(s) - borosilicate glass , materials science , diffusion , kinetics , phase (matter) , porosity , chemical engineering , composite material , chemistry , thermodynamics , physics , organic chemistry , quantum mechanics , engineering
The formation of a porous SiC‐depleted region in ZrB 2 –SiC due to active oxidation at ultrahigh temperatures was characterized. The presence/absence of SiC depletion was determined at a series of temperatures (1300°C–1800°C) and times (5 min–100 h). At T < 1627°C, SiC depletion was not observed. Instead, the formation of a ZrO 2 + C/borosilicate oxidation product layer sequence was observed above the ZrB 2 –SiC base material. At T ≥ 1627°C, SiC was depleted in the ZrB 2 matrix below the ZrO 2 and borosilicate oxidation products. The SiC depletion was attributed to active oxidation of SiC to form SiO(g). The transition between C formation in ZrO 2 ( T < 1627°C) and SiC depletion in ZrB 2 ( T ≥ 1627°C) is attributed to variation in the temperature dependence of thermodynamically favored product assemblage influenced by the local microstructural phase distribution. The growth kinetics of the SiC depletion region is consistent with a gas‐phase diffusion‐controlled process.