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Alternative Explanation for the Role of Magnesia in the Sintering of Alumina Containing Small Amounts of a Liquid Phase
Author(s) -
Kim ByungKi,
Hong SeongHyeon,
Lee SangHo,
Kim DohYeon,
Hwang g Moon
Publication year - 2003
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.1151-2916.2003.tb03351.x
Subject(s) - sintering , grain growth , materials science , microstructure , phase (matter) , magnesium , liquid phase , metallurgy , chemical engineering , grain size , mineralogy , chemistry , physics , organic chemistry , engineering , thermodynamics
The microstructural evolution during sintering of Al 2 O 3 was investigated to determine the role of MgO additive, particularly when its concentration is very low (<200 ppm). Compared with specimens without MgO, a few Al 2 O 3 grains were observed to grow enormously after the addition of 50 or 100 ppm MgO. When MgO content was increased to 200 ppm, on the other hand, the overall grain growth process was accelerated and many growing grains impinged on each other. In this case, therefore, a fine and unimodal grained microstructure was obtained. Sintering of Al 2 O 3 in a MgO atmosphere further supported the promotion of grain growth by MgO. It is proposed that MgO promotes the grain growth of Al 2 O 3 either by lowering the edge energy or by roughening the interface structure.