The role of beam dispersion in Raman and photo-stimulated luminescence piezo-spectroscopy of yttria-stabilized zirconia in multi-layered coatings

Liu, Dong; Lord, O. T.; Stevens, Oliver A. C.; Flewitt, Peter E J

doi:10.1016/j.actamat.2012.08.052

Cited by 27 publications

(9 citation statements)

References 52 publications

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“…The intensity of the spectrum measured underneath the YSZ was~10,000 times weaker than that measured on the scale on the bare bond coating. As noted by others [28,29] this decline in intensity is due to attenuation of both the incident and luminescent light by the YSZ layer. After 5 × 100 h cycles, spalled Al 2 O 3 -containing scale debris on the YSZ surface obscured the spectra from the interface but debris after 10 × 100 h cycles was removed using compressed air.…”

Section: Methodsmentioning

confidence: 86%

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The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

Lance

Unocic

Haynes

et al. 2014

Surface and Coatings Technology

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a b s t r a c t a r t i c l e i n f o Available online xxxx Keywords: Photo-stimulated luminescence piezospectroscopy (PLPS) Water vapor Bond coating Alumina scale TBCFurnace cycle testing of superalloy 1483 and X4 substrates with high velocity oxygen fuel (HVOF) NiCoCrAlYHfSi bond coatings and air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coatings was conducted at 1100°C in various environments. Average thermal barrier coating (TBC) lifetimes were 5-6 times longer when 100 h cycles were used to simulate base-load power generation operation, compared to the 1 h aero-engine standard cycle. Longer exposure times for 100 h cycles increased the interdiffusion resulting in no clear effects of H 2 O and CO 2 additions on average TBC lifetime for the 1483 substrates, contrary to the results with 1 h cycles where the addition of H 2 O reduced TBC lifetime. The lower Al content and perhaps the higher Ti content in 1483 compared to X4 resulted in lower TBC lifetimes for 1483. Photo-stimulated luminescence piezospectroscopy (PLPS) and 3D microscopy were used to measure residual stress in the alumina scale and surface roughness, respectively, on specimens with and without a YSZ top coating.

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Section: Methodsmentioning

confidence: 86%

“…It is well-known that the YSZ layer will increase the laser spot size at the thermally-grown scale due to light dispersion within the YSZ with estimates ranging from 20 μm [36][37][38] to 160 μm [29]. One factor that may improve the spatial resolution is the increased R-line signal from cracked scale [25,39].…”

Section: Resultsmentioning

confidence: 97%

The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

Lance

Unocic

Haynes

et al. 2014

Surface and Coatings Technology

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“…Layerremoval methods can be applied to investigate the stress distribution as a function of depth, but this is destructive (Watkins et al, 1997). Raman laser light could penetrate the thin layer of zirconia, but the light will spread in the coating, making it difficult to determine the interaction volume (Liu et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The nondestructive measurement of strain distributions in air plasma sprayed thermal barrier coatings as a function of depth from entire Debye–Scherrer rings

Xiao

Cernik

2020

J Appl Crystallogr

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The residual strain distribution has been measured as a function of depth in both top coat and bond coat in as-received and heat-treated air plasma sprayed thermal barrier coating samples. High-energy synchrotron X-ray beams were used in transmission to produce full Debye-Scherrer rings whose non-circular aspect ratio gave the in-plane and out-of-plane strains far more efficiently than the sin 2 method. The residual strain in the bond coat is found to be tensile and the strain in the phase of the as-received sample was measured. The residual strains observed in the top coat were generally compressive (increasing towards the interface), with two kinds of nonlinear trend. These was a 'jump' feature near the interface, and in some cases there was another 'jump' feature near the surface. It is shown how these trend differences can be correlated to cracks in the coating.

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“…For these two methods, to achieve the stress distribution as a function of depth, the samples need to be cross sectioned, ground and polished, which inevitably changes the strain distribution inside the sample. Also, for the Raman method, since zirconia is transparent for most lasers, the beam will spread inside the coating (Liu et al, 2013). This leads to considerable uncertainty in determining the measured sample volume, which in return affects the resolution of the measurement.…”

Section: Introductionmentioning

confidence: 99%

A synchrotron X-ray diffraction deconvolution method for the measurement of residual stress in thermal barrier coatings as a function of depth

Jacques

Chen

et al. 2016

J Appl Crystallogr

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The average residual stress distribution as a function of depth in an air plasmasprayed yttria stabilized zirconia top coat used in thermal barrier coating (TBC) systems was measured using synchrotron radiation X-ray diffraction in reflection geometry on station I15 at Diamond Light Source, UK, employing a series of incidence angles. The stress values were calculated from data deconvoluted from diffraction patterns collected at increasing depths. The stress was found to be compressive through the thickness of the TBC and a fluctuation in the trend of the stress profile was indicated in some samples. Typically this fluctuation was observed to increase from the surface to the middle of the coating, decrease a little and then increase again towards the interface. The stress at the interface region was observed to be around 300 MPa, which agrees well with the reported values. The trend of the observed residual stress was found to be related to the crack distribution in the samples, in particular a large crack propagating from the middle of the coating. The method shows promise for the development of a nondestructive test for as-manufactured samples.

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The role of beam dispersion in Raman and photo-stimulated luminescence piezo-spectroscopy of yttria-stabilized zirconia in multi-layered coatings

Cited by 27 publications

References 52 publications

The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

The nondestructive measurement of strain distributions in air plasma sprayed thermal barrier coatings as a function of depth from entire Debye–Scherrer rings

A synchrotron X-ray diffraction deconvolution method for the measurement of residual stress in thermal barrier coatings as a function of depth

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