Fluorescence studies of polycrystalline Al2O3 composite constituents: piezo-spectroscopic calibration and applications (Journal article)

Dassios, K. G./ Galiotis, C.


Optical fluorescence microscopy (OFM) was used to quantify the effect of applied stress or strain upon the position of the R fluorescence line of alpha-Al2O3 composite constituents (fibers and matrices) prior to composite processing. Polycrystalline Nextel(TM) Nextel 720 fibers were tested under tension and compression by means of a cantilever beam technique, whereas the polycrystalline matrix was tested in compression. The position of the R fluorescence line was correlated to applied strain and stress in order to provide the piezo-spectroscopic calibration curve and the corresponding coefficients for both sensors, which form the basis for interpretation of frequency shifts from full, all-alumina, composites. The piezo-spectroscopic coefficients of the polycrystalline matrix were found to be 2.57 cm(-1) GPa(-1) and 2.52 cm(-1) GPa(-1) for the R1 and R2 lines respectively, whereas the coefficients for the polycrystalline alpha-Al2O3 Nextel 720 fibers were found to be 3.07 cm(-1) GPa(-1) and 2.91 cm(-1) GPa(-1) for the R1 and R2 lines, respectively. The effects of collection probe size, as well as penetration depth, are discussed. The established piezo-spectroscopic behavior is used inversely to quantify the residual stresses in the as-received fibers due to the presence of sizing, as well as in the thermally grown alumina layer of an industrial thermal barrier coating.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μηχανικών Επιστήμης Υλικών
Keywords: optical fluorescence,bridging stresses,oxidation,sapphire,strain,scales,line,luminescence,dependence,crystal
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/13967
ISSN: 0947-8396
Link: <Go to ISI>://000221675000042
Publisher: Springer
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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