Analysis of the Cr3+ luminescence spectra from thermally grown oxide in thermal barrier coatings

Selçuk, Ahmet; Atkinson, A.

doi:10.1016/s0921-5093(01)01911-6

Cited by 72 publications

(42 citation statements)

References 9 publications

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“…The photoluminescence and Raman spectra of Cr 3 þ ions are known to be sensitive to the hydrostatic or biaxial stress in corundum structures [44][45][46] . More precisely, Nychka et al 44 and Selcuk et al 45 showed that the R 1 and R 2 luminescence lines have different piezo-spectroscopic coefficients so that the energy difference between them, DE, which is 4 meV in unstressed samples, increases with increasing compressive stress. It was demonstrated experimentally 44 that, up to a biaxial stress of 6 GPa, DE is linear in stress and increases by about 0.1 meV per GPa.…”

Section: Discussionmentioning

confidence: 99%

“…It was demonstrated experimentally 44 that, up to a biaxial stress of 6 GPa, DE is linear in stress and increases by about 0.1 meV per GPa. Above 6 GPa, no systematic measurements were carried out but a nonlinear behaviour is expected 45 . To further ascertain the presence of strain in our chromium oxide clusters, we therefore recorded micro-photoluminescence spectra in a backscattering configuration using a laser beam at 2.33 eV with a Rayleigh length of about 1 mm.…”

Section: Discussionmentioning

confidence: 99%

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Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters

et al. 2014

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The control of the magnetization of a material with an electric field would make the design and the integration of novel electronic devices possible. This explains the renewed interest in multiferroic materials. Progress in this field is currently hampered by the scarcity of the materials available and the smallness of the magnetoelectric effects. Here we present a proofof-principle experiment showing that engineering large strains through nanoscale size reduction is an efficient route for increasing magnetoelectric coefficients by orders of magnitude. The archetype magnetoelectric material, Cr 2 O 3 , in the form of epitaxial clusters, exhibits an unprecedented 600% change in magnetization magnitude under 1 V. Furthermore, a multiferroic phase, with both magnetic and electric spontaneous polarizations, is found in the clusters, while absent in the bulk.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters

et al. 2014

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“…It is clear that the measurement of Cr 3þ luminescence signals through relatively thick (%210 mm) air plasmasprayed coating is possible with quite a high S/N ratio, similar to a case of electron beam-physical vapor-deposited (EB-PVD) TBC. 29) In addition, the effect of luminescence signal from the Y 2 O 3 stabilized ZrO 2 TBC layer 14) could be neglected in the present case because there was no detection of Cr 3þ luminescence at the same wavelengths from a polished transverse section of the layer under the same luminescence measurement conditions. The effect of light scattering from a TBC layer usually appears in measured spectra because the latter contains many light scattering sources.…”

Section: Tgo Growth Behavior and Morphologymentioning

confidence: 91%

Detection of Micro-Damage Evolution of Air Plasma-Sprayed Y2O3-ZrO2 Thermal Barrier Coating through TGO Stress Measurement

2006

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The micro damage evolution behavior in air plasma-sprayed 8 mass% Y 2 O 3 stabilized ZrO 2 thermal barrier coating (APS-TBC) after isothermal heat exposure at 1150 C up to 200 h was observed. Residual stress of thermally-grown-oxide (TGO) layer was measured through the TBC layer using Cr 3þ luminescence spectroscopy and the measured stress levels were compared with micro damage evolution behavior stored in the TBC system. With heat exposure time of longer than 10 h, microfracture behaviors were noted in the TBC layer. In-plane residual stress of the TGO layer increased for up to 50 h of heat exposure time, and thereafter, diminished with further increase. These behaviors are strongly correlated with the thickness and the residual stress of the TGO layer. This decrease in the TGO stress well contrasts with the evolution of the micro fracture behavior, which is also related to the thickness and undulation of the formed TGO layer. The change of TGO stress, tgo , depending on the average thickness of the TGO layer, " h h tgo , i.e., d tgo =d " h h tgo is a useful indicator of the damage evolution in TGO:h h tgo > 0: slight damage stage, d tgo =d " h h tgo < 0: micro fracture evolution stage. The result suggests that Cr 3þ luminescence spectroscopy is a good indicator for micro damage evolution in the TBC layer and is a useful tool for nondestructive evaluation (NDE) of APS-TBC systems.

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“…The fitting procedure used two pseudo-Voigt functions [32][33][34] to obtain the following design variables for each of the R1 and R2 curves: area, line-widths, peak positions and shape factors (describing the Gaussian and Lorentzian characteristics). 35 RESULTS AND DISCUSSION Integrated intensity maps: particle dispersion verification The capability of detecting and measuring the R-lines from a-alumina nanoparticles embedded within an epoxy resin was determined and verified in this work. Photo-stimulated luminescence readings from all three a-alumina-epoxy nanocomposites were obtained as shown in Figure 7, showing strong intensities from the 25 and 38% samples.…”

Section: Deconvolution and Curve Fitting Of Spectral Datamentioning

confidence: 89%

Characterization of particle dispersion and volume fraction in alumina-filled epoxy nanocomposites using photo-stimulated luminescence spectroscopy

Stevenson

Jones

Raghavan

2011

Polym J

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A novel method is presented to validate the dispersion of a-alumina nanoparticles within a polymer matrix, as well as to create a calibration for filler particle volume fraction identification. Using photo-stimulated luminescence spectroscopy (PSLS), spectral information from a-alumina-filled epoxy nanocomposites consisting of varying volume fraction quantities of alumina nanoparticles was collected and analyzed. Surface contour maps of each nanocomposite were created by comparing integrated intensity data from the R1 curve of a-alumina throughout each specimen. These maps show satisfactory dispersion of alumina in the 5 and 25% volume fraction composites, whereas agglomerations were detected in various regions of the 38% nanocomposite, establishing the capability of this method to characterize photo-luminescent particle dispersion. This new approach also provides high spatial resolution, which can be used to determine the exact locations of voids, inclusions and/or agglomerations, while also predicting the volume percentage of photo-luminescent particle content within a specimen, lending itself as a quality control method in the manufacturing of these composites. Keywords: alumina nanocomposites; nanoparticle dispersion; photo-stimulated luminescence spectroscopy INTRODUCTIONThermosetting polymers, such as epoxy resins, are currently being used in aerospace applications because of the ease for which their molecular structure can be modified, as well as their ability to sufficiently bond with various filler materials. 1 Typically, un-reinforced epoxies show poor resistance to crack initiation and propagation. 2 As a result, epoxies are commonly reinforced with filler particles, or modifiers, that alter their molecular structure by increasing the already dense cross-linked network structure of the epoxy, resulting in improved mechanical properties, such as strength, stiffness and toughness.Recent research has indicated that using nano-sized particles improves the stiffness, strength and toughness of a polymer without sacrificing the thermomechanical properties. 2,3 In addition, nanoparticles have a higher specific surface area than micron-sized particles, as more of these particles can be integrated within a specific volume, enabling an overall increase in the mechanical properties of the matrix. 1,4,5 Commonly embedded nanoparticles include aluminum oxide, 6-8 , calcium silicate 6 and titanium oxide. 6,9 With the improvement in mechanical properties, these nanocomposites have applications as ballistic materials with high-impact resistance. 10,11 Owing to a high dielectric strength, alumina-filled epoxy composites are also used in high-voltage applications, such as the encapsulation of ferroelectric elements for shock depoling. 12

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Analysis of the Cr3+ luminescence spectra from thermally grown oxide in thermal barrier coatings

Cited by 72 publications

References 9 publications

Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters

Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters

Detection of Micro-Damage Evolution of Air Plasma-Sprayed Y<SUB>2</SUB>O<SUB>3</SUB>-ZrO<SUB>2</SUB> Thermal Barrier Coating through TGO Stress Measurement

Characterization of particle dispersion and volume fraction in alumina-filled epoxy nanocomposites using photo-stimulated luminescence spectroscopy

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