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Tanaka, Hirokazu; Sawai, Shinya; Morimoto, K.; Hisano, K.

doi:10.1023/a:1011538022439

Cited by 32 publications

(10 citation statements)

References 5 publications

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“…Many investigations were carried out with emphasis on the performance of thermal barrier coatings and therefore, cover wavelengths in the µm range at comparatively moderate temperatures [8][9][10]. Most of the papers reported measurements of reflectivities.…”

Section: Yttria-stabilized Zirconia (Ysz) Unfortunatelymentioning

confidence: 99%

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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Section: Yttria-stabilized Zirconia (Ysz) Unfortunatelymentioning

confidence: 99%

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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“…4 and 5, respectively. The data were taken from the literature [19,20] and used in the calculations described above.…”

Section: Results and Analysismentioning

confidence: 99%

Development and Characterization of Low-Emitting Ceramics

et al. 2007

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The infrared-optical properties of ceramics are correlated with the complex index of refraction of the material and the structure of the ceramic. By changing these parameters, the infrared-optical properties can be changed over a relatively wide range. The correlation of the structural properties (like the porosity or the pore sizes) and the material properties (such as the complex index of refraction on the one hand and the infrared-optical properties such as emittance on the other) are described by a solution of the equation of radiative transfer and the Mie-theory. Within this work, low-emitting ceramics, which have significantly lower emittances than conventional ceramics, were prepared by optimizing their composition and structure. The spectral emittance of these ceramics was measured, and a total emittance dependent on temperature was calculated from the spectral emittance. As a result, one obtains ceramics which have a total emittance of 0.2 at a temperature of 1,100 K. In comparison to conventional ceramics with a typical total emittance of 0.8 at 1,100 K, the use of such low-e ceramics leads to a reduction in heat transfer of about 70% via thermal radiation. The results of our calculations were compared with experimental data to validate the theory.

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“…The choice of the surface emissivity was based on the measurements of Tanaka et al 25) on sintered zirconia, and assumed to be equal to 0.7.…”

Section: Modellingmentioning

confidence: 99%

“…In this study, a value of 0.7 was chosen, based on the measurements of Tanaka et al 25) on sintered zirconia. The specimen temperatures calculated from Eq.…”

Section: Specimen Temperaturementioning

confidence: 99%

Measurement and modelling of electrical resistivity by four-terminal method during flash sintering of 3YSZ

Yoshida

Falco

Todd

2018

J. Ceram. Soc. Japan

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Flash sintering is a newly developed technique to quickly densify conductive ceramics in the presence of an electric field. At a critical combination of field and temperature, densification takes place in a few seconds. This paper investigates the electrical resistivity during flash sintering of 3YSZ by the four-terminal method in combination with numerical modelling of electrical heating and temperature distributions. Densification rates were similar to those observed previously in specimens rapidly heated by methods not involving direct electrical heating. Temperature gradients caused by heat loss from the surface and non-uniform electrical heating led to differential sintering, specimen distortion and non-uniform grain size. The four point measurements revealed significant contact resistance at the power supply electrodes and allowed accurate measurement of the resistivity under the high current conditions of flash sintering. The specimen resistivity was lower for a given temperature under high current conditions and this was attributed to electronic conduction. Concurrent sintering led to a progressive reduction of resistivity during heating causing an increase in the apparent activation energy for electrical conduction. When the effect of sintering on resistivity was accounted for, the onset conditions for the "flash event" were accurately predicted on the basis of thermal runaway.

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Untitled

Cited by 32 publications

References 5 publications

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

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

Development and Characterization of Low-Emitting Ceramics

Measurement and modelling of electrical resistivity by four-terminal method during flash sintering of 3YSZ

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