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Diffusion and Creep in Silica-Doped Tetragonal Zirconia

Ghosh, Santonu and Kilo, Martin and Borchardt, Guenter and Chokshi, Atul H (2009) Diffusion and Creep in Silica-Doped Tetragonal Zirconia. In: Journal of the American Ceramic Society, 92 (12). pp. 3004-3013.

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Silica segregation at two grain junctions or in amorphous triple junction pockets can influence creep by altering the grain-boundary diffusion coefficient. Although the addition of silica to superplastic yttria-stabilized tetragonal zirconia enhances ductility, differences in reported creep parameters have limited critical identification of rate controlling mechanisms. The present study on a pure 3 mol% yttria-stabilized tetragonal zirconia (3YTZ) and 3YTZ with 0.39 or 3.9 wt% silica involved a detailed characterization of creep over a wide range of experimental conditions and also tracer diffusion measurements. The data broadly show transitions in creep stress exponents from n∼1 to ∼2 to ∼3 with a decrease in the stress. The data at high stresses are consistent with Coble diffusion creep, and creep at lower stresses is attributed to interface-controlled diffusion creep. Measurements indicated that silica does not have any significant influence on grain boundary or lattice diffusion, and this is consistent with the observation that 3YTZ and 3YTZ with 0.39% or 3.9% silica exhibit essentially identical creep behavior in the Coble creep regime. Silica influences the interface control process so that the transitions in stress exponents are pushed to lower stresses with an increase in silica content.

Item Type: Journal Article
Publication: Journal of the American Ceramic Society
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 11 Jan 2010 06:37
Last Modified: 19 Sep 2010 05:53
URI: http://eprints.iisc.ac.in/id/eprint/25269

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