A Dynamic Technique for Measurements of Thermophysical Properties at High Temperatures

1981 ◽  
Vol 9 ◽  
Author(s):  
Ared Cezairliyan
Keyword(s):  
Melting Temperature ◽  
Thermophysical Properties ◽  
Solid Phase ◽  
Electrical Current ◽  
Heat Of Fusion ◽  
Electrically Conducting ◽  
Current Voltage ◽  
Dynamic Experiments ◽  
Hemispherical Total Emittance ◽  
Total Emittance

ABSTRACTA technique is described for the dynamic measurements of selected thermophysical properties of electrically conducting substances in the range 1500 K to the melting temperature of the specimen. The technique is based on rapid resistive self-heating of the specimen from room temperature to any desired high temperature in less than one second by the passage of an electrical current pulse through it and on measuring the pertinent quantities, such as current, voltage and temperature, with millisecond resolution. The technique was applied to the measurements of heat capacity, electrical resistivity, hemispherical total emittance, normal spectral emittance, thermal expansion, melting temperature, heat of fusion, and temperature and energy of solid-solid phase transformations. Upper temperature of the measurements has been limited by the melting temperature of the specimen, at which point, the specimen collapses due to the gravitational force. In order to be able to extend the measurements to the liquid phase, performance of the dynamic experiments in a near-zero gravity environment is suggested.

scholarly journals Melting of iron determined by X-ray absorption spectroscopy to 100 GPa

2015 ◽  
Vol 112 (39) ◽  
pp. 12042-12045 ◽  
Author(s):  
Giuliana Aquilanti ◽  
Angela Trapananti ◽  
Amol Karandikar ◽  
Innokenty Kantor ◽  
Carlo Marini ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Absorption Spectroscopy ◽  
Inner Core ◽  
Solid Phase ◽  
Melting Curve ◽  
X Ray ◽  
Core Boundary ◽  
Diamond Anvil ◽  
Laser Heated ◽  
X Ray Absorption

Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa.

scholarly journals Nano-ion-exchangers - a new class of reactive materials

2018 ◽  
Vol 18 (6) ◽  
pp. 794-809
Author(s):  
Anatoly M. Dolgonosov ◽  
Ruslan Kh. Khamizov ◽  
Nadezhda K. Kolotilina
Keyword(s):  
Solid Phase ◽  
Ionic Composition ◽  
Photo Luminescence ◽  
Colloidal Systems ◽  
Ion Exchangers ◽  
New Class ◽  
Counter Ions ◽  
Dynamic Experiments ◽  
Back Ground ◽  
Charged Ions

Nano-sized particles of functional polymers i.e. nano-ion-exchangers (NIEX), are unusual objects which simultaneously behave as the hyper-charged ions and the solid ion exchangers. Due to similar charges, they form very stable colloidal systems. This paper is devoted to theoretical and practical study of the proper- ties of nano-exchangers, methods for their preparation, the technique of experiments being practically un- known, and the opportunities for their application. The results of dynamic experiments are given for sorption of nano-exchangers and the ions of back- ground solutions on the beds of macro-particles of usual cationic and anionic resins. It is shown how to ob- tain the NIEX hydrosols with the desired ionic composition, and the concept of the standard state hydrosol is defined. The possibility for solid-phase exchange of counter ions between contacting particles of the same polarity is demonstrated. The possibilities and advantages of using nano-ion-exchangers in chemical analysis are demonstrat- ed by different examples: preparation of separating phases for ion chromatography, application as modifier in capillary electrophoresis and using in photo-luminescence. The prospects of nano-ion-exchangers for drug delivery are also shown.

ChemInform Abstract: Pressure Dependence of the Heat of Fusion and Melting Temperature of Indium.

ChemInform ◽  
2010 ◽  
Vol 27 (28) ◽  
pp. no-no
Author(s):  
G. W. H. HOEHNE ◽  
W. DOLLHOPF ◽  
K. BLANKENHORN ◽  
P. U. MAYR
Keyword(s):  
Melting Temperature ◽  
Pressure Dependence ◽  
Heat Of Fusion

Ni/Si solid phase reaction studied by temperature-dependent current-voltage technique

2003 ◽  
Vol 93 (2) ◽  
pp. 866-870 ◽  
Author(s):  
Yu-Long Jiang ◽  
Guo-Ping Ru ◽  
Fang Lu ◽  
Xin-Ping Qu ◽  
Bing-Zong Li ◽  
...  
Keyword(s):  
Solid Phase ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Temperature Dependent ◽  
Current Voltage

Thermodynamics of Crystallization in High Polymers. Natural Rubber

1955 ◽  
Vol 28 (3) ◽  
pp. 718-727 ◽  
Author(s):  
Donald E. Roberts ◽  
Leo Mandelkern
Keyword(s):  
Natural Rubber ◽  
Melting Temperature ◽  
Low Temperatures ◽  
Rapid Heating ◽  
Heat Of Fusion ◽  
Low Molecular Weight ◽  
Heating Rates ◽  
Equilibrium Melting Temperature ◽  
Clapeyron Equation ◽  
Melting Temperatures

Abstract The existence of an equilibrium melting temperature, T0m, at 28 ± 1°, for unstretched natural rubber has been established, using dilatometric methods. The lower melting temperatures previously observed are a consequence of the low temperatures of crystallization and the rapid heating rates employed. From melting point studies of mixtures of the polymer with low molecular-weight diluents, the heat of fusion per repeating unit, ΔHu has been evaluated as 15.3 ± 0.5 cal./g. The values of ΔHu and T0m have then been combined with data of other workers to obtain the following information concerning natural rubber: (1) The variation of melting temperature with applied hydrostatic pressure has been calculated from the Clapeyron equation to be 0.0465° C/atm. (2) The degree of erystallinity resulting from maintaining a sample at 0° until the rate of crystallization is negligible has been calculated, by three independent methods, to be in the range 26 to 31 per cent. (3) Analysis of the stress-strain-temperature relationship has indicated that crystallization is the cause of the large internal energy changes that are observed at relatively high elongations.

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