Raman Spectroscopic Method for Analyzing Residual Stresses in Ceramic Composites

Pezzotti, Giuseppe; Zhu, Wenliang

doi:10.1007/978-94-007-2739-7_78

Cited by 2 publications

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“…An algorithm written using RStudio (RStudio, Team 2015) allowed automatic calculations which efficiently handled a large number of spectra with respect to the intensity and spectral position of selected bands. Residual stresses in the constituent phases of the ZTA heads were computed from spectral shifts according to piezo-spectroscopic coefficients previously calibrated for the bands at 145 for t -ZrO 2 , 178 for m -ZrO 2 , and 415 for Al 2 O 3 cm −1 as −0.6, −0.9, and −0.76 cm −1 /GPa, respectively [ 19 , 20 ]. Negative piezo-spectroscopic coefficients represent compressive stress fields which induce spectral shifts of the Raman bands toward higher frequencies and vice versa for tensile stresses.…”

Section: Methodsmentioning

confidence: 99%

In Vitro versus In Vivo Phase Instability of Zirconia-Toughened Alumina Femoral Heads: A Critical Comparative Assessment

et al. 2017

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A clear discrepancy between predicted in vitro and actual in vivo surface phase stability of BIOLOX®delta zirconia-toughened alumina (ZTA) femoral heads has been demonstrated by several independent research groups. Data from retrievals challenge the validity of the standard method currently utilized in evaluating surface stability and raise a series of important questions: (1) Why do in vitro hydrothermal aging treatments conspicuously fail to model actual results from the in vivo environment? (2) What is the preponderant microscopic phenomenon triggering the accelerated transformation in vivo? (3) Ultimately, what revisions of the current in vitro standard are needed in order to obtain consistent predictions of ZTA transformation kinetics in vivo? Reported in this paper is a new in toto method for visualizing the surface stability of femoral heads. It is based on CAD-assisted Raman spectroscopy to quantitatively assess the phase transformation observed in ZTA retrievals. Using a series of independent analytical probes, an evaluation of the microscopic mechanisms responsible for the polymorphic transformation is also provided. An outline is given of the possible ways in which the current hydrothermal simulation standard for artificial joints can be improved in an attempt to reduce the gap between in vitro simulation and reality.

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Section: Methodsmentioning

confidence: 99%