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Convection Patterns in Liquid Oxide Films on ZrB 2 –SiC Composites Oxidized at a High Temperature
Author(s) -
Karlsdottir Sigrun N.,
Halloran John W.,
Henderson Carl E.
Publication year - 2007
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/j.1551-2916.2007.01784.x
Subject(s) - materials science , oxide , zirconium diboride , layer (electronics) , convection , composite material , zirconium , chemical engineering , metallurgy , thermodynamics , physics , engineering
During the high‐temperature oxidation of ZrB 2 –SiC composites, liquid boron oxide (B 2 O 3 ) is formed at the zirconium diboride–zirconium oxide interface and transported through the overlying layer of silica liquid by convection, forming distinct convection cells arranged like the petals of a flower. The convection cells are localized by a viscous fingering phenomenon, as the fluid B 2 O 3 rich liquid solution rises through the viscous silica layer. The upwelling B 2 O 3 rich liquid contains dissolved zirconium dioxide, which deposits in the center of the flower‐like structure as the B 2 O 3 evaporates. The driving force for the B 2 O 3 liquid flow is the volume increase upon oxidation of ZrB 2 . Convective transport of B 2 O 3 liquids suggests a novel mechanism for the high‐temperature oxidation of these materials.