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Development of Surface Compressive Stresses in Zirconia–Alumina Composites by an Ion‐Exchange Process
Author(s) -
Lin GuangYong,
Virkar Anil V.
Publication year - 2001
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.1151-2916.2001.tb00836.x
Subject(s) - materials science , composite material , compressive strength , flexural strength , weibull modulus , composite number , cubic zirconia , ceramic
A two‐step ion‐exchange technique was developed for introducing compressive stresses on the surface of ZrO 2 –Al 2 O 3 composites. In the first step, a thin layer (∼250 μm) of Na‐β″‐Al 2 O 3 was formed on the surface of the composite by a vapor‐phase process at ∼1400°C. In the second step, Na + ions were replaced by K + ions by a heat treatment at ∼385°C for 2 h in a molten KNO 3 bath. Replacement of sodium by potassium led to the creation of surface compressive stresses. The flexural strength and Weibull modulus of ZrO 2 –Al 2 O 3 composite were ∼915 MPa and 10, respectively, for the as‐sintered samples. By contrast, the flexural strength and Weibull modulus were ∼1140 MPa and 26, respectively, for the ion‐exchanged samples. A residual surface compressive stress of ∼480 MPa was measured by a strain‐gauge technique in K + ‐ion‐exchanged samples. The presence of surface compressive stresses also was confirmed using an indentation technique. The technique developed here can be used to introduce compressive stresses on components of virtually any shape.