Advances in high-temperature calorimetry: A comparison

Schlesinger, Mark E.; Jacob, Susan

doi:10.1007/s11837-004-0233-0

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…Heat capacity data for undercooled liquids have been published for low-melting elements (Ga [10,11], In, Bi, Sn [12] and Se [13,14]) and several high-melting metals (Au, Cu, Ag [15]). Experimental determination of C P is usually performed by calorimetry [16]. However, conventional methods are usually limited to temperatures below 1000 • C. Detailed descriptions of the experimental methods that can be used to extract high-temperature data on liquids are given in Appendix A. Measurements of undercooled liquids pose special challenges.…”

Section: Liquids Above and Below T Mmentioning

confidence: 99%

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Becker

Ågren

Baricco

et al. 2013

Physica Status Solidi (b)

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We describe current approaches to thermodynamic modelling of liquids for the CALPHAD method, the use of available experimental methods and results in this type of modelling, and considerations in the use of atomic-scale simulation methods to inform a CALPHAD approach. We begin with an overview of the formalism currently used in CALPHAD to describe the temperature dependence of the liquid Gibbs free energy and outline opportunities for improvement by reviewing the current physical understanding of the liquid. Brief descriptions of experimental methods for extracting high-temperature data on liquids and the preparation of undercooled liquid samples are presented.Properties of a well-determined substance, B 2 O 3 , including the glass transition, are then discussed in detail to emphasize specific modelling requirements for the liquid. We then examine the two-state model proposed for CALPHAD in detail and compare results with experiment and theory, where available. We further examine the contributions of atomic-scale methods to the understanding of liquids and their potential for supplementing available data. We discuss molecular dynamics (MD) and Monte Carlo methods that employ atomic interactions from classical interatomic potentials, as well as contributions from ab initio MD. We conclude with a summary of our findings.1 Introduction Although few inorganic materials are used in their liquid state, liquids play an important role in the manufacture of many materials. This can be either because they are processed from the liquid or, for fulfilling performance criteria, the formation of the liquid phase must be avoided. Additionally, there are now a number of commercially available amorphous solids, both in the form of oxides and metallic glasses, and accurate descriptions of these sys-tems are necessary over a wide range of temperatures. How-ever, liquid phases of many inorganic substances are only sta-ble at high temperatures where the experimental determination of their properties is more challenging than at lower tem-peratures. Many amorphous phases are, at best, metastable and their properties can be difficult to measure. In addition, the data from glassy phases cannot be directly applied to modelling liquids because they have gone through the glass transition, with the attendant sharp drop in heat capacity. As a result, the experimental data for generating and evaluating models of liquids and glasses are fairly sparse. This has a significant impact on the development and refinement of models that strongly depend on the availability of thermodynamic data, such as those needed in CALPHAD modelling.CALPHAD is one of the major ways to model the thermodynamics of liquids. However, for many systems, especially the unaries (elements and sometimes compounds), the data necessary to develop, parameterize and validate models are limited. Theoretical approaches, e.g. first-principles or classical atomistic simulation, can help provide data

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Section: Liquids Above and Below T Mmentioning

confidence: 99%

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Becker

Ågren

Baricco

et al. 2013

Physica Status Solidi (b)

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“…A Netzsch STA 409 CD‐type synchronous thermal analyzer was used to provide high‐resolution thermogravimetry (TG), and differential scanning calorimetry (DSC) with long‐term stability was used to ensure high sensitivity and accuracy of the DSC sensor at elevated temperatures. [ 16,17 ] The Netzsch STA 409 CD‐type synchronous thermal analyzer was thus selected for measuring

C_{normalp}

of the slag. In a typical experiment for determining

C_{normalp}

, experiments involving a blank measurement, sapphire measurement (standard), and sample measurement were subsequently conducted.…”

Section: Methodsmentioning

confidence: 99%

Mineral Transform and Specific Heat Capacity Characterization of Blast Furnace Slag with High Al₂O₃ in Heating Process

Zheng

Liang

et al. 2020

steel research int.

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The specific heat capacity (Cp) of blast furnace (BF) slag critically impacts BF smelting and reports on the Cp of BF slag with high Al2O3 are rare. Mineral transform and Cp characterization of synthesized BF slag (CaO–SiO2–MgO–Al2O3) with high Al2O3 in the heating process are herein discussed. Differential scanning calorimetry curves show a major exothermic peak at a low temperature and multiple endothermic peaks at elevated temperatures. The exothermic peak at approximately 920 °C appears when amorphous SiO2 (or SiO2 in silicate) becomes crystal SiO2 (or SiO2 in silicate). The endothermic peak between 1224–1254 °C is attributed to the reverse eutectic reaction, CaO·Al2O3·2SiO2 + 2CaO·0.5MgO·0.5Al2O3·1.5SiO2 → Liquid, along a eutectic line. CaO·Al2O3·2SiO2 + MgO·SiO2 → Liquid + 2MgO·SiO2 (reverse peritectic reaction) or CaO·Al2O3·2SiO2 + 2MgO·SiO2 → Liquid (reverse eutectic reaction) at approximately 1268 °C will occur with an endothermic reaction in some cases. The sharp endothermic peak between 1282 and 1303 °C is the reverse eutectic reaction, CaO·SiO2 + 2CaO·Al2O3·SiO2 → Liquid. The blunt endothermic peak between 1388 and 1447 °C is the residual slag melting, Solid → Liquid. The relationships of Cp with temperatures and compositions (R, ratio of w(MgO)/w(Al2O3), and w(Al2O3)) are established with a good fit.

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“…Results from earlier models of this type of instrum ent show good agreement w ith literature values. To summarize, high-tem perature (heat-flux) DSC shows potential for making therm odynam ic measurements at tem peratures above 1000°C[36].As noted previously, the Carleton University DSC facility is a high-tem perature (heatflux) DSC. The instrum ent is discussed in further detail in Chapter 5.…”

mentioning

confidence: 85%

“…Losses at tem peratures above 650°C make the stability and repeatability of measurement signals increasingly unreliable. Thus, this type of DSC is not suitable for hight tem perature inorganic m aterials such at 7 -TiAl[30,33,36].…”

mentioning

confidence: 99%

Thermophysical property and phase transformation determination of gamma-TiAl intermetallics

Overton¹

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Advances in high-temperature calorimetry: A comparison

Abstract: Several types of high-temperature calorimeters are compared in this paper. The calorimetry methods reviewed are drop, adiabatic, pulse, differential scanning, and, the newest method, high-temperature differential scanning.

Cited by 7 publications

References 7 publications

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Mineral Transform and Specific Heat Capacity Characterization of Blast Furnace Slag with High Al₂O₃ in Heating Process

Thermophysical property and phase transformation determination of gamma-TiAl intermetallics

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Advances in high-temperature calorimetry: A comparison

Abstract: Several types of high-temperature calorimeters are compared in this paper. The calorimetry methods reviewed are drop, adiabatic, pulse, differential scanning, and, the newest method, high-temperature differential scanning.

Cited by 7 publications

References 7 publications

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Mineral Transform and Specific Heat Capacity Characterization of Blast Furnace Slag with High Al2O3 in Heating Process

Thermophysical property and phase transformation determination of gamma-TiAl intermetallics

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Mineral Transform and Specific Heat Capacity Characterization of Blast Furnace Slag with High Al₂O₃ in Heating Process