Thermal radiation and optical properties of cubic zirconia stabilised with yttria up to the temperature of high rate evaporation

Петров, В. А.; Vorobyev, Aleksey; Chernyshev, Aleksander P.

doi:10.1068/htjr077

Cited by 17 publications

(21 citation statements)

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“…The responses from these different regions then contribute to the transient value of the reflectivity. As a consequence, the measured transient values of the reflectivity to the same surface temperature may considerably differ in the heating and cooling phases of a laser-heated sample as reported by Petrov et al [20]. We fully agree with the conclusion of the authors "that the reflectivity and emissivity under intense laser heating are not physical constants which may be related to some temperature, but depend on the temperature field in the surface layer of the sample."…”

Section: Discussionsupporting

confidence: 80%

“…Although the conditions of our calculations are not strictly identical with the experimental conditions for the reflectivity measurements reported in [20], the same qualitative results are obtained: the reflectivity values measured with laser-heated samples differ considerably for the heating and cooling phases and both values are different from the isothermal values. These deviations strongly increase with increasing power of the heating laser (compare Fig.…”

Section: Discussionsupporting

confidence: 54%

“…The differences in the hypothetical temperature distributions reported by the authors of [20] and the ones reported in this work (compare Fig. 5 of [20] with our Figs. 5b, 8b, 11b, 11d) are due to the different experimental conditions.…”

Section: Discussioncontrasting

confidence: 48%

“…These deviations strongly increase with increasing power of the heating laser (compare Fig. 7 in [20] with Fig. 7 of the present work).…”

Section: Discussionmentioning

confidence: 71%

“…Based on the work of Makino et al [19], the two values, S = 1 × 10 4 m −1 and S = 5 × 10 4 m −1 , were chosen for the scattering coefficient. Since the model developed so far cannot deal with wavelength-dependent optical properties, we restricted the analysis to one characteristic wavelength, and we used the absorption coefficients at 0.63 µm calculated from the reflectivity data of Petrov et al [20] with Eq. 50 (see Table 1).…”

Section: Simulation: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

Modeling Transient Heat Conduction and Radiative Transport in Semitransparent Media: A Tool for the Interpretation of Reflectivity Data

Musella

Tschudi

2007

Int J Thermophys

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In this work the problem of interpretation of reflectivity data for semitransparent materials at high temperatures is addressed. A detailed analysis of the transient thermal response of a participating medium subjected to a pulse of finite energy is performed using a new method developed to solve the general equation of energy transfer for a conductive, absorbing, emitting, and scattering medium. The model, previously presented for a material with constant optical properties (Musella, Tschudi, Int J Thermophys 26:981, 2005), has been upgraded to encompass a much wider scenario where the thermophysical and optical properties are temperature dependent. This allows the study of the transient reflectivity of laser-heated samples where high heating rates and strong temperature gradients occur near the surface. Considerable differences of the reflectivity values for the same surface temperature calculated in the heating and cooling phases, both different from the corresponding values for an isothermal sample, are reported in accordance with experimental results.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionsupporting

confidence: 54%

Section: Discussioncontrasting

confidence: 48%

“…These deviations strongly increase with increasing power of the heating laser (compare Fig. 7 in [20] with Fig. 7 of the present work).…”

Section: Discussionmentioning

confidence: 71%

Section: Simulation: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Modeling Transient Heat Conduction and Radiative Transport in Semitransparent Media: A Tool for the Interpretation of Reflectivity Data

Musella

Tschudi

2007

Int J Thermophys

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Detection of Melting Temperatures and Sources of Errors Using Two-Color Pyrometry During In-flight Measurements of Atmospheric Plasma-Sprayed Particles

2008

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Growing demands on the quality of plasma-sprayed coatings require reliable methods to monitor and optimize the spraying processes. As the coating microstructures are dependent on the characteristics of the powder feedstock, particle in-flight diagnostics is of great importance. In particular, the melting status of the particles is critical in this regard. Thus, the accurate determination of the particle temperature is necessary. In-flight particle temperature measurements during atmospheric plasma spraying (APS) of tungsten, molybdenum, and yttria-stabilized zirconia by two-color pyrometry were analyzed statistically. The diagnostic tool applied is the DPV-2000 (Tecnar). The particle temperature distributions allow for assessment of the melting status of the particles as well as the identification of the melting temperature and particle fractions in the molten and solidification state. Furthermore, the relevant systematic and material-dependent sources for measurement errors using two-color pyrometry were investigated. Their influence was carefully estimated and corrected. As long as there are reliable data available on the emissivity of the powder material, good agreement between the corrected measured melting temperatures and the reference data can be expected.

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Abrupt Increase of the Absorption Coefficient of Alumina at Melting by Laser Radiation and Its Decrease at Solidification

Петров¹

2009

Int J Thermophys

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Experimental data for the normal-hemispherical reflectivity R of remolded aluminum oxide ceramics for wavelengths of (0.488, 0.6328, 1.15, and 3.39) µm and effective (radiance) temperatures T eff1 and T eff2 for wavelengths of 0.55 µm and 0.72 µm were obtained in the process of rapid subsecond heating by CO 2 laser radiation in air and vacuum from room temperature to the formation of thin molten layers of 0.6 mm to 0.7 mm thickness and of subsequent rapid free cooling with solidification of the melt when the laser radiation was blocked. Experimentally and by numerical simulation of combined radiation and conduction heat transfer, the influence of the heating radiation flux on the formation of the thin melt on the surface of ceramics with an abrupt increase of T eff1 and T eff2 and on the signal of the spectrometer in the infrared range from 2 µm to 11µm at melting and on its decrease at solidification were studied. The radiation heat flux varied from 500 W · cm −2 to 2000 W · cm −2 . It is shown that the determining effect on the temperature field and on the intensity of outgoing radiation is caused by the formation of the isothermal continuous two-phase zone and the abrupt increase (decrease) of the absorption coefficient of the melt. The importance of kinetics in the abrupt change of the absorption coefficient of molten Al 2 O 3 is noted.

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Thermal radiation and optical properties of cubic zirconia stabilised with yttria up to the temperature of high rate evaporation

Cited by 17 publications

References 0 publications

Modeling Transient Heat Conduction and Radiative Transport in Semitransparent Media: A Tool for the Interpretation of Reflectivity Data

Modeling Transient Heat Conduction and Radiative Transport in Semitransparent Media: A Tool for the Interpretation of Reflectivity Data

Detection of Melting Temperatures and Sources of Errors Using Two-Color Pyrometry During In-flight Measurements of Atmospheric Plasma-Sprayed Particles

Abrupt Increase of the Absorption Coefficient of Alumina at Melting by Laser Radiation and Its Decrease at Solidification

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