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Early‐Stage Thermal Oxidation of Carbothermal β‐Sialon Powder
Author(s) -
Shimada Shiro,
Aoki Takenori,
Kiyono Hajime,
MacKenzie Kenneth J. D.
Publication year - 1998
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.1151-2916.1998.tb02331.x
Subject(s) - mullite , sialon , amorphous solid , thermogravimetry , aluminosilicate , materials science , chemical engineering , dissolution , amorphous silica , powder diffraction , carbothermic reaction , amorphous silica alumina , mineralogy , crystallography , chemistry , metallurgy , catalysis , organic chemistry , ceramic , carbide , engineering
Early‐stage thermal oxidation (below 1100°C) of carbothermally synthesized β‐sialon powder was monitored by X‐ray powder diffraction, solid‐state 29 Si and 27 Al MAS NMR spectroscopy, and thermogravimetry. No crystalline oxidation products were detected by XRD but 29 Si and 27 Al MAS NMR indicated the early formation of amorphous silica, followed by the formation of an amorphous aluminosilicate with an atomic environment similar to that of mullite. The initial oxidation was described by a linear kinetic law with an activation energy of 170 kJmol −1 , suggesting the rate‐limiting step to be due to dissolution of O 2 in an amorphous silica surface layer on the β‐sialon particles.