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Diffusion and Creep in Silica‐Doped Tetragonal Zirconia
Author(s) -
Ghosh Santonu,
Kilo Martin,
Borchardt Günter,
Chokshi Atul H.
Publication year - 2009
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.1551-2916.2009.03321.x
Subject(s) - creep , materials science , diffusion creep , lattice diffusion coefficient , grain boundary , superplasticity , grain boundary diffusion coefficient , grain boundary sliding , composite material , tetragonal crystal system , stress (linguistics) , yttria stabilized zirconia , metallurgy , cubic zirconia , crystallography , effective diffusion coefficient , microstructure , ceramic , crystal structure , chemistry , medicine , linguistics , philosophy , magnetic resonance imaging , radiology
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.