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Oxidation of Manganese Ferrite
Author(s) -
WEISZ R. S.
Publication year - 1957
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.1151-2916.1957.tb12590.x
Subject(s) - bixbyite , hematite , manganese , spinel , materials science , ferrite (magnet) , pyrolusite , recrystallization (geology) , metallurgy , ceramic , activation energy , precipitation , mineralogy , inorganic chemistry , chemistry , oxide , composite material , geology , paleontology , organic chemistry , physics , meteorology
The oxidation of manganese ferrite (MnFe 2 O 4 ) in air has been studied in the temperature range 750° to 1150°C. Between 1050° and 1150° a homogeneous oxidation takes place, resulting in a spinel phase of a defect type containing up to 10% of the manganese in the trivalent state. At 1050° and below, bixbyite (Mn 2 O 3 ) and hematite (Fe 2 O 3 ) are precipitated. The kinetics indicate that initially a diffusion‐limited homogeneous reaction takes place, followed by precipitation and grain growth. At lower temperatures, well‐defined Widmanstätten precipitates are formed; at higher temperatures, recrystallization alters these precipitates. The oxidation of manganese ferrite can be strongly retarded by a ceramic glaze, offering a practical method of preparing the material by air firing.