Pulsed Heating of Carbides

Savvatimskiy, A. I.; Onufriev, S. V.; Muboyajan, S. A.; Цыганков, П. А.

doi:10.3103/s1062873818040184

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…A plethora of techniques is available for high temperature study of metal alloys. The “exploding wire” technique [ 8 , 9 ] has been in development for more than 300 years and has also been adapted for electrically conductive carbides and nitrides [ 10 , 11 , 12 , 13 ]. In this method, pulse discharge through a metallic wire or conducting ceramic coating provides instantaneous heating and excludes any contamination from the container.…”

Section: Introductionmentioning

confidence: 99%

Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

et al. 2021

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Densities of liquid oxide melts with melting temperatures above 2000 °C are required to establish mixing models in the liquid state for thermodynamic modeling and advanced additive manufacturing and laser welding of ceramics. Accurate measurements of molten rare earth oxide density were recently reported from experiments with an electrostatic levitator on board the International Space Station. In this work, we present an approach to terrestrial measurements of density and thermal expansion of liquid oxides from high-speed videography using an aero-acoustic levitator with laser heating and machine vision algorithms. The following density values for liquid oxides at melting temperature were obtained: Y2O3 4.6 ± 0.15; Yb2O3 8.4 ± 0.2; Zr0.9Y0.1O1.95 4.7 ± 0.2; Zr0.95Y0.05O1.975 4.9 ± 0.2; HfO2 8.2 ± 0.3 g/cm3. The accuracy of density and thermal expansion measurements can be improved by employing backlight illumination, spectropyrometry and a multi-emitter acoustic levitator.

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Section: Introductionmentioning

confidence: 99%

Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

et al. 2021

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“…The binary systems of zirconium and hafnium with nitrogen and carbon were studied experimentally from circa 1000 °C to liquidus temperatures and most of the systematic studies of phase equilibria were performed before 1970. New experimental results on melting temperature determination and thermodynamic properties of single phases were published since then [61,62,63,64,65,66], and an entirely new stream of thermodynamic data has emerged from ab initio computations [1,67,68,69].…”

Section: Phase Diagramsmentioning

confidence: 99%

“…Due to the microseconds timeframe of discharge, the heat losses can be neglected, and the total energy is known from the capacitor calibration. Recently, this approach was successfully applied for carbides and nitrides films 100 µm or thinner [61,63,64,65,66,161,162] and the first experimental data on fusion enthalpies and high temperature heat capacities of ZrC and ZrN were reported. The fusion enthalpy of ZrN was measured as 104 kJ/mol [65], and the fusion enthalpy of ZrC x was found to increase from 92 kJ/mol for ZrC to 111 kJ/mol for ZrC 0.95 .…”

Section: Rocksalt (Oxy)carbonitridesmentioning

confidence: 99%

“…The fusion enthalpy of ZrN was measured as 104 kJ/mol [65], and the fusion enthalpy of ZrC x was found to increase from 92 kJ/mol for ZrC to 111 kJ/mol for ZrC 0.95 . The experimental setup described by Savvatimskiy et al [63] provides black body-like geometry for measurements by a sighting pyrometer inside the wedge formed by glass plates coated with the sample. We expect that future applications of the “exploding wire” technique to metallic nitrides and carbides will result in an explosion in much needed thermodynamic data for Calphad modeling of carbonitride systems and for testing the predictions of ab initio computations.…”

Section: Rocksalt (Oxy)carbonitridesmentioning

confidence: 99%

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Carbides and Nitrides of Zirconium and Hafnium

et al. 2019

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Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and oxygen solubility limits. The systematic experimental studies on phase equilibria and thermodynamics were performed mainly 40–60 years ago, mostly for binary systems of Zr and Hf with C and N. Since then, synthesis of several oxynitrides was reported in the fluorite-derivative type of structures, of orthorhombic and cubic higher nitrides Zr3N4 and Hf3N4. An ever-increasing stream of data is provided by ab initio computations, and one of the testable predictions is that the rocksalt HfC0.75N0.22 phase would have the highest known melting temperature. Experimental data on melting temperatures of hafnium carbonitrides are absent, but minimum in heat capacity and maximum in hardness were reported for Hf(C,N) solid solutions. New methods, such as electrical pulse heating and laser melting, can fill the gaps in experimental data and validate ab initio predictions.

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Specific heat of refractory carbides (ZrC_0.95, HfC_0.85 and Ta_0.8Hf_0.2C) in the temperature interval 2500-5000 K

Savvatimskiy

Аристова

Onufriev

et al. 2020

J. Phys.: Conf. Ser.

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A fast method for studying the physical properties of substances is considered, -heating by a single current pulse for 5-8 µs. Its advantages over the stationary methods is in obtaining bulk thermophysical properties of carbides at high temperatures (2500-5000 K). The temperature was measured by an optical method using high-speed photo-detectors PDA-10A (Thorlabs) and temperature lamp calibration. There is a sharp increase in the heat capacity of the solid phase for « 300 K before melting for all the studied carbides. It is assumed that the reason for the accelerated growth of heat capacity is associated with the formation of paired Frankel defects, in conditions of insufficient time for saturation of the volume with equilibrium vacancies.

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Pulsed Heating of Carbides

Cited by 7 publications

References 8 publications

Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

Carbides and Nitrides of Zirconium and Hafnium

Specific heat of refractory carbides (ZrC_0.95, HfC_0.85 and Ta_0.8Hf_0.2C) in the temperature interval 2500-5000 K

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Pulsed Heating of Carbides

Cited by 7 publications

References 8 publications

Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator

Carbides and Nitrides of Zirconium and Hafnium

Specific heat of refractory carbides (ZrC0.95, HfC0.85 and Ta0.8Hf0.2C) in the temperature interval 2500-5000 K

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Specific heat of refractory carbides (ZrC_0.95, HfC_0.85 and Ta_0.8Hf_0.2C) in the temperature interval 2500-5000 K