Simultaneous measurements of specific heat and total hemispherical emissivity of chromel and alumel by a transient calorimetric technique

Sasaki, Seizi; Masuda, Hidetoshi; Higano, Mitsuo; HISHINUMA, Noboru

doi:10.1007/bf01563713

Cited by 33 publications

(11 citation statements)

References 8 publications

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“…was determined by measuring %/eT as a function of temperature in the HVHTESL and combining with specific heat capacity data obtained by DSC. The hemispherical total emissivity e.r, which is the ratio of energy emitted by a material at a temperature T with respect to a blackbody at the same temperature, has been measured for several solid metals [43][44][45][46], alloys [47], and semiconductors [48]. However, there is a lack of emissivity data on liquid metals and only recently first results were reported for undercooled liquid metals [17].…”

Section: E a S U R E M E N T S O F T H Ementioning

confidence: 98%

Containerless processing of the undercooled metallic melts — overview

Kim

1995

Metals and Materials

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Brief overview of current containerless electrostatic levitation processing technique and research progress of the area of bulk metallic glass formation is introduced. Undercooling behavior during solidification of the bulk metallic glass forming Zh~ :Til~.sCu~,,.sNi~0,Be2z, alloy has been studied using the containerless electrostatic levitation processing technique. The melt is successfully undercoolcd to the glass transition temperature forming the amorphous phase with the proper thermal treatment. Differential scanning calorimetry (DSC) is used to determine the Gibbs free energy difference between the crystal and the undercooled liquid. The results indicate that the Gibbs free energy difference between the metastable undercooled liquid and the crystalline solid of the Zr4~:Tit~RCuzzsNi~arjB~,_, alloy is relatively small compared to that of conventional metallic glass forming binary, alloys even for large undercoolings. The hemispherical total emissivity of undercooled liquid is measured in the whole region of undercooled liquid state. Due to the combining effects of excellent thermal stability of the undercooled liquid in the Zr4, _,.Ti13.,Cu~zsNi~0.nBcz~.~ alloy with unique experimental technique of the containerless electrostatic levitation processing, it is possible to construct the complete time-temperature-transformation ('ITr) diagram. The measured TIT diagram exhibiting the expected "C"shape can not be satisfactorily explained by the existing models due to the complex crystallization mechanisms.

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Section: E a S U R E M E N T S O F T H Ementioning

confidence: 98%

Containerless processing of the undercooled metallic melts — overview

Kim

1995

Metals and Materials

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“…The value for the emissivity of the thermocouple bead in this equation is problematical in that a single value is difficult to ascertain since it is strongly dependent on such characteristics as surface roughness, oxidation and any impurities or coatings on the material [29]. Although chromel and alumel wire emissivities have been measured independently and have been reported as having an emissivity of 0.14 at 760 K, rising at a rate of between 0.010 and 0.015 per 100 K [30], no single value has appeared for the combination of these two materials, although a value of between 0.20 and 0.25 at 1500 K, has been suggested [29]. Therefore, taking an emissivity of 0.2, and a measured temperature of 400°C, the measured temperature is in error by about 0.5%, but this increases non-linearly to 4% for a measured temperature of 1200°C, Figure 13.…”

Section: Thermocouple Temperature Correctionsmentioning

confidence: 99%

Examining the Potential Fire Risk from a Short Duration Pyrotechnic Event

Disimile

Toy

2007

Fire Technol

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This study originated from trying to determine the fire risk from an armor piercing incendiary (API) passing close to flammable material. Since the temperature field produced by such a device was unknown the temperature distribution within the luminous region of a flash/fireball of laboratory-made cylindrical test charges of Barium Nitrate/Magnalium (Ba(NO 3 ) 2 /Mg-Al) mixture, similar in composition to that of an API, was measured. The measurements have been acquired with 78.7 lm (40 gauge) high-speed K-type thermocouples that have an upper temperature limit of 1372°C. It was found that even though the thermocouples could not be located closer than 20 mm from the surface of the charges without failure, temperature differences of up to 350°C were recorded above the charge to that below. Furthermore, the heat release has a significant effect on the rate at which the temperature decays away from the surface of the charge, and this characterizes its pyrotechnic effect. In addition to the temperature measurements some image analysis has shown that the luminous region of the fireball was some 17 times larger than the charge itself, but the reaction zone was only a fraction of this size. Furthermore, this reaction zone was not as symmetrical as assumed and was probably due to an irregular burning process as the combustion wave traversed the test charge.

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“…Finally, the total hemispherical emissivity can be obtained with an integrating sphere operating over a very wide spectral range or a goniometer module measurement the radiation for every directions and every wavelengths [36]. However, the most famous and certified method for evaluating this quantity is still the well-known calorimetric method [37], [38]. These methods are interesting because the total hemispherical emissivity can be directly measured.…”

Section: Please Cite This Article As Doi:101063/15116425mentioning

confidence: 99%

A fast and versatile method for spectral emissivity measurement at high temperatures

Bakali

Gilblas

Pottier

et al. 2019

Review of Scientific Instruments

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In this paper, the development of a new device for high temperature emissivity measurement is described. This device aims at measuring both spectral and total emissivity for a thermal range of 600 to 1000°C. The device main targeted properties were both versatility and simplicity. To do so, a rigorous selection was made for each component: heating system, heat source, sample holder, measuring devices. Sample dimensions and the corresponding sample holder were optimized through a ray tracing model computation. Selection of sensors to compute a total emissivity was also especially discussed. A NIR spectrometer, and two MIR cameras covering [3-5] and [7.5-13]µm equipped with optical filters were chosen for spectral measurements. The major impediment was the separation between sample signal and various spurious signals emitted by environment. A specific measurement methodology was then made for each bandwidth to resolve this issue. A reference material was chosen for the device validation: Platinum. Spectral emissivity measurements were then compared to values from a commercial spectrometer. A good agreement was found for NIR and the first MIR band measurements and a higher error was seen in MIR second band which is explained by a less favorable signal to noise ratio. Integrated emissivity is then calculated and compared to values found in the literature. A good agreement between those values is found and similar trends with temperature are observed. The device is then validated for spectral and total emissivity measurement. Device versatility and simplicity allows an easy adaptation to a large area of applications.

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Simultaneous measurements of specific heat and total hemispherical emissivity of chromel and alumel by a transient calorimetric technique

Cited by 33 publications

References 8 publications

Containerless processing of the undercooled metallic melts — overview

Containerless processing of the undercooled metallic melts — overview

Examining the Potential Fire Risk from a Short Duration Pyrotechnic Event

A fast and versatile method for spectral emissivity measurement at high temperatures

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