Method of enthalpy calibration for differential scanning calorimeters

Metrologiya ◽  
2021 ◽  
pp. 40-52
Author(s):  
T. A. Kompan ◽  
V. I. Kulagin ◽  
V. V. Vlasova
Keyword(s):  
Phase Transitions ◽  
New Method ◽  
Specific Enthalpy ◽  
New Materials ◽  
Standard Samples ◽  
International Union ◽  
Output Control ◽  
Input And Output ◽  
Accuracy Of Measurements ◽  
Differential Scanning Calorimeters

The article describes a new method for enthalpy calibration of differential scanning calorimeters. The method allows you to remove the limitation on the temperature range in which this metrological procedure can be carried out. The proposed method does not require the use of standard samples of heats of fusion, therefore, it is not limited by the thermophysical properties of the certified substances. The developed method solves the problem of increasing the accuracy of measurements of specific enthalpy and heats of phase transitions of various substances for all types of differential scanning calorimeters. The effectiveness of the method in solving this problem is confirmed and illustrated by the authors by comparing the results of measuring the heats of fusion of a number of metals. The results obtained on differential scanning calorimeters calibrated by the new method and on the same instruments, but calibrated in accordance with the generally accepted standardized method of the International Union of Theoretical and Applied Chemistry, were compared. The authors experimentally revealed the advantages of the new method in terms of saving time and money required for calibration. The article will be of interest to those specialists who use differential scanning calorimeters in the development of new materials, control of technological processes, production, input and output control, as well as to those specialists who develop methods for research and measurement of various materials on differential scanning calorimeters.

Differential Scanning Calorimetry (DSC)

2008 ◽  
Author(s):  
José A. Martinho Simões ◽  
Manuel Minas da Piedade
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transitions ◽  
Small Samples ◽  
Calorimetric Data ◽  
Scanning Calorimetry ◽  
The Difference ◽  
Temperature Dependent Properties ◽  
Differential Scanning Calorimeters ◽  
New Applications ◽  
User Friendly

Physical and chemical changes may often be induced by raising or lowering the temperature of a substance. Typical examples are phase transitions, such as fusion, or chemical reactions, such as the solid state polymerization of sodium chloroacetate, which has an onset at 471 K: ClCH2COONa (cr) ⇋ NaCl (cr) + 1/n − (CH2COO)n − (pol) Differential scanning calorimetry (DSC) was designed to obtain the enthalpy or the internal energy of those processes and also to measure temperature-dependent properties of substances, such as the heat capacity. This is done by monitoring the change of the difference between the heat flow rate or power to a sample (S) and to a reference material (R), ΔΦ = ΦS − ΦR = (dQ/dt)S − (dQ/dt)R, as a function of time or temperature, while both S and R are subjected to a controlled temperature program. The temperature is usually increased or decreased linearly at a predetermined rate, but the apparatus can also be used isothermally. In some cases DSC experiments may provide kinetic data. According to Wunderlich, differential scanning calorimeters evolved from the differential thermal analysis (DTA) instruments built by Kurnakov at the beginning of the twentieth century. In these early DTA apparatus, the temperature difference between a sample and a reference, simultaneously heated by a single heat source, was measured as a function of time. No calorimetric data could be derived, and the instruments were used, for example, to determine the temperatures of phase transitions and to identify metals, oxides, minerals, soils, and foods. The attempts to obtain calorimetric data from DTA instruments eventually led to the development of DSC. The term differential scanning calorimetry and the acronym DSC were coined in 1963 when the first commercial instrument of this type became available. This apparatus was easy to operate, enabled fast experiments, and required only small samples (typically 5–10 mg). Its importance for materials characterization was immediately demonstrated and the DSC technique soon experienced a boom. New user-friendly commercial instruments were developed, and new applications were explored. It is, however, somewhat ironic that the method ows its still growing popularity to analytical rather than calorimetric uses.

scholarly journals Study of the Drell-Yan process with the pair-production of polarized tau leptons in collisions of polarized proton beams

2019 ◽  
Vol 222 ◽  
pp. 03021
Author(s):  
A. Aleshko ◽  
E. Boos ◽  
V. Bunichev
Keyword(s):  
Parton Distribution ◽  
Polarization State ◽  
Distribution Functions ◽  
Hadronic Decay ◽  
New Method ◽  
Tau Leptons ◽  
Parton Distribution Functions ◽  
Accuracy Of Measurements ◽  
Polarized Proton

The new method for studying polarized parton distribution functions via the Drell-Yan process with tau production is proposed. The hadronic decay of tau to single charged pi-meson and neutrino is utilised for determination of the polarization state of the tau-lepton. The key feature of our approach is that we do not sum over the polarizations states of tau, but preserve this information through energies ofpions produced in corresponding decays. The new method in addition to existing ones should improve the accuracy of measurements of polarized structure functions of hadrons. In the current work, the feasibility of such an approach is assessed through numerical simulations.

ESTABLISHING OF THE SPATIAL DISTRIBUTION OF DISPOSABLE GROUNDWATER RESOURCES BY MULTI-CRITERIA ANALYSIS METHOD

2018 ◽  
Vol 471 ◽  
pp. 137-146
Author(s):  
Andrzej RODZOCH ◽  
Dominik MIAZ ◽  
Grzegorz JELENIEWICZ
Keyword(s):  
Mathematical Model ◽  
Spatial Distribution ◽  
Model Simulation ◽  
Groundwater Resources ◽  
Analysis Method ◽  
Control Data ◽  
Output Control ◽  
Input And Output ◽  
Management Area

A hydrogeologist often faces a serious difficulty in estimation of available groundwater resources. In contrast to renewable water resources, which are valuable for a study area and estimated with greater or lower precision depending on the quality of available data, disposable groundwater resources cannot be treated as a natural and relatively constant characteristic of the management area, because their size and spatial distribution depend on criteria assumed to set an optimal way for managing water supplies. Since those criteria can be defined in various ways and their significance can vary as well, spatial distribution of groundwater resources and their size can theoretically have infinite number of equally correct solutions. They can be only treated as optimal for a strictly specified set of criteria and therefore can be modified according to different needs and assumed priorities. Interpreted this way, they can only be calculated by the use of model simulation, because only a mathematical model is an effective tool for making such multi-criteria analyses. The paper presents an approach for setting criteria that limit the input and output control data, applied by HYDREKO in the process of spatial distribution of disposable groundwater resources. An example of use of this method is presented for the management area P-XVIII Dolna Warta (Rodzoch et al., 2017).

Transparent ferroelectric ceramics: Phase transitions and new materials

1981 ◽  
Vol 34 (1) ◽  
pp. 153-155 ◽  
Author(s):  
A. R. Sternberg ◽  
V. Y. Fritsberg ◽  
L. A. Shebanov ◽  
A. Y. Dobre
Keyword(s):  
Phase Transitions ◽  
Ferroelectric Ceramics ◽  
New Materials

Determination of Specific Failure Work on Compact Steel Samples

2019 ◽  
Vol 945 ◽  
pp. 569-573 ◽  
Author(s):  
M.R. Abdulganiev ◽  
R.N. Khasanov ◽  
V.A. Gafarova
Keyword(s):  
Mechanical Characteristics ◽  
Oil And Gas ◽  
Material Degradation ◽  
Standard Samples ◽  
Accuracy Of Measurements ◽  
Testing Performance ◽  
Tension Testing ◽  
Hardness Values

For critical structures in the oil and gas refining, petrochemical and chemical industries, it is necessary to determine the value of mechanical characteristics. In the present paper we consider issues related to the determination of the mechanical characteristics of structural materials using compact samples. Basically, current values ​​of the mechanical properties of materials are determined by measuring hardness using existing empirical dependences that combine hardness values ​​with yield limit and tensile strength values. But such dependencies are not universal and require experimental verification. The need for compact samples application occurs during determination of the reasons of equipment failure, when the size of a fragment of broken down equipment does not allow producing standard samples for traditional testing performance. The application of empirical dependencies for determination of hardness mechanical characteristics is complicated by the fact that it is necessary to take into account the degree of the material degradation. This, in its turn, requires additional studies. The key issue in determining the accuracy of measurements on compact samples is the role of the surface in the formation of fracture focal points. The experiments were carried out on thin steel samples and the mechanical characteristics were determined on Instron 8801 dynamometer unit. It was shown that in case of increase of thickness of the samples that underwent tension testing, the fracture work varies according to the power law.

New Method for Reducing Harmonics Involved in Input and Output of Rectifier with Interphase Transformer

1986 ◽  
Vol IA-22 (5) ◽  
pp. 790-797 ◽  
Author(s):  
Shota Miyairi ◽  
Shoji Iida ◽  
Kiyoshi Nakata ◽  
Shigeo Masukawa
Keyword(s):  
New Method ◽  
Input And Output

Dynamic Testing of Magnetic Elastomer Material Prototypes

2019 ◽  
Vol 945 ◽  
pp. 369-373 ◽  
Author(s):  
A.J. Minaev ◽  
J.V. Korovkin
Keyword(s):  
Magnetic Field ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Dynamic Testing ◽  
Considerable Effect ◽  
Experimental Results ◽  
New Materials ◽  
Resonant Frequencies ◽  
Input And Output ◽  
The Magnetic Field

This research is aimed at obtaining the experimental dynamic characteristics of new materials (magnetoactive elastomers exposed to the magnetic field). It demonstrates that the strength of a magnetic field has a considerable effect on the increase in the resonant frequencies of tested materials. For tests, we used a vibration stand equipped with virtual meters to visualize the experimental results on a computer display. We herein present an example of recording the frequency response on the magnetic elastomer sample input and output when exposed to vibrations caused by the unbalanced motor forces.

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