The effect of grain boundary phase on contact damage resistance of alumina ceramics

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The effect of grain boundary phase on contact damage behavior is investigated in alumina ceramics. Four types of aluminas doped with MgO, anorthite (CaO·Al2O3·2SiO2), silica, and with both MgO and anorthite are prepared such that they have similar average grain size by adjusting sintering conditions. MgO-doped alumina composed of equiaxed grains shows brittle fracture behavior, and anorthite-doped alumina composed of elongated grains shows a quasi-plastic response under Hertzian sphere indentation. The co-doped alumina with MgO and anorthite, however, is damage tolerant even with its rounded grains, while silica-doped alumina with similar grain size and shape to anorthite-doped alumina shows abrupt strength degradation with low critical load for cone cracking. The damage behavior is discussed from the viewpoint of residual stress induced by thermal expansion mismatch between the grains and grain boundary phases. The damage tolerant behavior of alumina ceramics is significantly affected by the composition of grain boundary phase.
Publisher
Springer Verlag
Issue Date
2004
Citation

Journal of Materials Science, Vol.39, pp.7023-7030

ISSN
0022–2461
URI
http://hdl.handle.net/10203/25201
Appears in Collection
MS-Journal Papers(저널논문)

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