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Anomalous Temperature Dependence of the Growth Rate of the Reaction Layer between Silica and Molten Aluminum
Author(s) -
Yoshikawa Noboru,
Kikuchi Atsushi,
Taniguchi Shoji
Publication year - 2002
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.1151-2916.2002.tb00360.x
Subject(s) - isothermal process , atmospheric temperature range , phase (matter) , aluminium , decomposition , hydrogen , chemistry , reaction rate , kinetic energy , growth rate , materials science , thermodynamics , analytical chemistry (journal) , metallurgy , catalysis , organic chemistry , geometry , mathematics , physics , quantum mechanics
An aluminum/Al 2 O 3 composite body is produced by a displacement reaction between SiO 2 and molten aluminum. The growth rate of the reaction layer possesses negative (anomalous) temperature dependence at 1000–1300 K. This study compared reported reaction‐kinetic data and investigated causes for this temperature dependence. The reaction product, Al 2 O 3 , changed from the γ‐/θ‐Al 2 O 3 phase to the α‐Al 2 O 3 phase in this temperature range and α‐Al 2 O 3 became the dominant phase at >1273 K. Isothermal transformation of the γ‐/θ‐Al 2 O 3 product phases to the α‐Al 2 O 3 phase was also observed. Morphologies and scales of the Al 2 O 3 phases change drastically at 1173 K; this transition occurred in a spatially discontinuous manner. Reaction‐rate retardation was interpreted in terms of occurrence of the competitive and simultaneous reactions to produce different Al 2 O 3 phases in this temperature range. It was also found that the hydrogen release from the raw SiO 2 and the SiO 2 phase transformation were not related to the negative temperature dependence.