Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 197
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Full Record for Micrograph 197

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Micrograph no
197
Brief description
Partially Stabilised Zirconia (PSZ)
Keywords
ceramic Link to MATTER Glossary entry for ceramic, engineering ceramic, tough ceramic, toughness Link to MATTER Glossary entry for toughness, zirconia
Categories
Ceramic
System
ZrO2-MgO
Composition
MgO 2.5-3.6, ZrO2 97.5-96.4 (wt%)
Standard codes
Reaction
Processing
All commercial PSZ’s require a solution heat treatment at above about 1750ºC to develop a supersaturated solid solution prior to an ageing cycle which ideally forms tetragonal ZrO2 precipitates in a cubic matrix. Typical ageing temperatures are 1400-1500ºC.
Applications
Hip prostheses, thermal barrier coatings on turbine blades, feeler gauges, drawing dies.
Sample preparation
Grind, polish, ion thin and carbon coat.
Technique
Bright-field TEM
Length bar
300 nm
Further information
The image shows cross sections through the oblate spheroid (like Smarties or M and M’s) tetragonal precipitates in the cubic matrix. On interaction with a propagating crack these transform to monoclinic symmetry expanding to close the crack so increasing toughness, so-called transformation toughening.
Contributor
Prof W E Lee
Organisation
Department of Engineering Materials, University of Sheffield
Date
02/09/02
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales