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Direct evidence for continuous linear kinetics in the low-temperature degradation of Y-TZP

Paper ID Volume ID Publish Year Pages File Format Full-Text
938 69 2013 10 PDF Available
Title
Direct evidence for continuous linear kinetics in the low-temperature degradation of Y-TZP
Abstract

The kinetics of the tetragonal to monoclinic (t–m) transformation of zirconia in a hydrous environment at 134 °C and 3 bar pressure was studied. As surface X-ray diffraction, which is conventionally used to explore the progress, has a very limited depth of information, it distorts the quantitative results in a layer-on-layer situation and by itself is ill suited for this reason. Analyzing cross sections is more suitable; therefore, focused ion beam techniques were used to prepare artifact-free cuts. The material was subsequently investigated by scanning electron microscopy, electron backscatter diffraction and Raman spectroscopy. Only the combination of methods makes it possible to resolve the quantifiable details of the process. The transformation starts in the near-surface areas, forms a layer, and the growth of this layer proceeds into the bulk material following a simple linear time law (0.0624 μm h−1 for material in the chosen condition), without apparent retardation or limit. The progress yields a gradientless layer with a fixed amount of residual tetragonal zirconia (∼27% for 3Y-TZP in the present conditions) separated from unaffected material by a boundary, which has a roughness only in the grain size range. The kinetics indicates a reaction rate control, where the hydration reaction is the key factor, but is modified by the stepwise access of water to the reaction front opened by the autocatalytic transformation of zirconia with a critical hydration level.

Keywords
Zirconia; Low temperature degradation; Bioceramics; Phase transformation; TZP
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Direct evidence for continuous linear kinetics in the low-temperature degradation of Y-TZP
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Publisher
Database: Elsevier - ScienceDirect
Journal: Acta Biomaterialia - Volume 9, Issue 1, January 2013, Pages 4826–4835
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us