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Critical Concentration of MgO for the Prevention of Abnormal Grain Growth in Alumina
Author(s) -
Bae So Ik,
Baik Sunggi
Publication year - 1994
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.1151-2916.1994.tb04634.x
Subject(s) - sintering , solvent drag , grain growth , materials science , impurity , abnormal grain growth , chemical engineering , grain size , metallurgy , doping , grain boundary , microstructure , chemistry , organic chemistry , engineering , optoelectronics
The effects of MgO on sintering and grain growth of alumina in the absence of any other impurities as well as in the presence of various amounts of CaO were investigated using ultrapure (>99.999%) alumina and sintering at 1900°C for 1 h in a clean contamination‐free condition. Critical concentrations of MgO required for the prevention of abnormal grain growth were linearly dependent on the CaO concentration. For a given concentration of CaO, at least the same amount of MgO has to be added to prevent abnormal grain growth. MgO addition alone to the ultrapure alumina enhanced both grain growth and densification kinetics during pressureless sintering. The beneficial effect of MgO doping could not be explained based on the solute drag (or pinning) model. It was more likely to be understood in terms of either a glass modification model or a solid–liquid interface modification model.