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Glass‐Phase Movement in Yttria‐Stabilized Zirconia/Alumina Composites
Author(s) -
Knibbe Ruth,
Auchterlonie Graeme J.,
Mori Toshiyuki,
Lashtabeg Anna,
Drennan John
Publication year - 2010
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.1551-2916.2010.03612.x
Subject(s) - materials science , sintering , yttria stabilized zirconia , composite material , phase (matter) , cubic zirconia , grain boundary , impurity , thermal expansion , ceramic , microstructure , chemistry , organic chemistry
The mechanism for siliceous liquid‐phase movement during sintering and thermal etching is investigated using single crystal alumina rods in a yttria‐stabilized zirconia (YSZ) matrix. Bulk glass‐phase extraction and intergranular movement during sintering is attributed to a chemically driven force; however, glass‐phase expulsion is predominately due to thermal expansion differences in the glass phase, alumina fiber, and YSZ matrix. An increased understanding of the glass‐phase mechanism will facilitate the reduction of the resistive grain‐boundary phase, which consequently will decrease the operating temperature of high‐temperature solid oxide fuel cells. In this paper, we demonstrated that scavengers such as alumina in combination with a suitable thermal treatment can be used to purify the grain boundaries from unwanted impurities, such as Si, through the expulsion of the unwanted liquid impurity phase. The driving forces behind the expulsion are mechanically and chemically driven capillary flow.