Levitation Calorimetry Research Articles

Enthalpy measurements of undercooled melts by levitation calorimetry: the pure metals nickel, iron, vanadium and niobium

A circulating gas cooling (CGC) system is added to a combination of an electromagnetic levitation apparatus and a drop calorimeter to measure the enthalpies of the pure metals nickel, iron, vanadium and niobium in the undercooled temperature range. The CGC system extends the experimental temperature range to lower temperatures. The effect of the CGC system on the heat losses during the drop of the sample is discussed and the evaluation procedure presented. The measured enthalpies of the metals in the undercooled range confirm the temperature dependences of the enthalpies of the liquid phase above their melting points.

The Entropies of Fusion For Group Vb and VIb Metals

AbstractBased on the vacancy theory for the fusion process, the entropies of fusion of group Vb and VIb metals were assessed by means of their physical properties in the solid and liquid states. The total entropy is divided into contributions from the interactional, configurational, volumic and vibrational changes. The entropies of fusion calculated in this manner were found to be in agreement with our experimental results performed by levitation calorimetry. The higher values of the entropies of fusion of the Vb and VIb group metals relative to those given by Tammann's rule are considered to be due to the increased vibrational contribution and bonding characteristics. Resume En se basant sur la theorie lacunaire du procede de fusion, les entropies de fusion des metaux des groupes Vb et VIb ont ete estimees a partir de leurs proprietes physiques dans les etats solides et liquides. L'entropie totale est divisee en plusieurs contributions provenant des changements interactionnels, configurationnels, volumiq...

Modern methods in high temperature calorimetry

High temperature calorimetric methods used in metallurgy are discussed. Two types of isoperibolic mixing calorimeters are presented. They allow to determine directly the enthalpy of mixing of liquid alloys as a function of concentration and temperature and to measure the derivative as a function of concentration for temperatures up to 1300 K and 2000 K, respectively. A high temperature solution calorimeter in which a liquid metal or alloy is used as the bath (maximum temperature 1800 K) can be used to determine the heat of formation of solid alloys and to measure the partial enthalpy of mixing at infinite dilution. With a drop calorimeter it is possible to measure the thermodynamic properties of highly reactive alloy systems. Thermodynamic measurements of high melting refractory metals and alloys for temperatures up to 4000 K can be achieved with levitation calorimetry.

ChemInform Abstract: ENTHALPY MEASUREMENTS ON SOLID AND LIQUID TUNGSTEN BY LEVITATION CALORIMETRY

By means of levitation calorimetry the enthalpy of solid and liquid tungsten was determined in the temperature range 3176 to 4017 K. For the solid state Hoch's equation with summarized coefficients was fitted to the measured points: H(T)-H(298)= - 7873 + 24.943 T + 3.7474 x 10/sup -4/ T/sup 2/ + 1.5716 x 10/sup -10/ T/sup 4/ + 11.9851 x 10/sup 4/ T/sup -1/ (Jmol/sup -1/). From the enthalpies the heat capacities were calculated and compared with earlier data also at lower temperatures. In the liquid state a linear temperature dependence was found: H(T)-H(298) = 168364 + 53.763 (T-T(s-l) (Jmol/sup -1/). From the difference of the enthalpies in liquid and solid state the melting data were determined as ..delta..H(s-l) = 50340 +- 376 (Jmol/sup -1/) and ..delta..S(s-l) = 13.67 +- 0.10 (Jmol/sup -1/K/sup -1/).

Enthalpy Measurements on Solid and Liquid Tungsten by Levitation Calorimetry

Enthalpy Measurements on Solid and Liquid Tungsten by Levitation Calorimetry

Thermodynamic properties by levitation calorimetry ? V. High-temperature heat content of liquid gallium

The heat content (enthalpy) of liquid gallium relative to the supercooled liquid state at 298.15 K has been measured by levitation calorimetry over the temperature range 1412–1630 K. Thermal energy increments were determined using an aluminum block calorimeter of conventional design. The sharp decrease of C p with increasing temperature observed just above the melting point does not persist up to the high temperatures of the present work. When combined with recent laser-flash calorimetry results from the literature, the present work indicates that C p is 26.46 ± 0.71 J · g-atom−1 · K−1 over the temperature range 587–1630 K.

Enthalpy Measurements on Refractory Metals and Alloys by Levitation Calorimetry

AbstractMeasurements of enthalpy by levitation drop‐calorimetry. Principle of measurement. Experimental data of Nb, Mo, Ta in solid and liquid state. Determination of enthalpies of mixing by levitation technique. Temperature measurement. Investigation of Fe–Cu and Nb–Si‐alloys.

ChemInform Abstract: ENTHALPY MEASUREMENTS ON SOLID AND LIQUID TANTALUM BY LEVITATION CALORIMETRY

Chemischer InformationsdienstVolume 13, Issue 51 Physical Inorganic Chemistry ChemInform Abstract: ENTHALPY MEASUREMENTS ON SOLID AND LIQUID TANTALUM BY LEVITATION CALORIMETRY E. ARPACI, E. ARPACISearch for more papers by this authorM. G. FROHBERG, M. G. FROHBERGSearch for more papers by this author E. ARPACI, E. ARPACISearch for more papers by this authorM. G. FROHBERG, M. G. FROHBERGSearch for more papers by this author First published: December 21, 1982 https://doi.org/10.1002/chin.198251016Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue51December 21, 1982 RelatedInformation

Enthalpy Measurements on Solid and Liquid Tantalum by Levitation Calorimetry

Enthalpy Measurements on Solid and Liquid Tantalum by Levitation Calorimetry

The high temperature heat content and heat capacity of liquid cerium-copper alloys by levitation calorimetry

The electromagnetic method of heating was used to determine the heat contents of liquid-cerium-copper alloys over the complete range of alloy composition. The temperatures of the levitated samples were determined pyrometrically utilizing the normal spectral emissivity data measured in an earlier work. The heat capacity was derived from analytic expression for heat contents. The composition dependence of the heat capacity goes through a maximum at 67 at. pct Cu. This behavior is ascribed to the effect of a Ce-Cu2-type atomic clustering in the liquid phase.

Enthalpy Measurements on Solid and Liquid Niobium by Means of Levitation Calorimetry

Enthalpy Measurements on Solid and Liquid Niobium by Means of Levitation Calorimetry

The heat capacities and heat content of molten cerium by levitation calorimetry

The heat capacities and heat content of molten cerium by levitation calorimetry

The heat capacities and heat content of molten cerium by levitation calorimetry

A 15 kVa, 450 kHz radio frequency generator was used to levitate and melt cerium samples ranging in size from 0.4 to 1.7 g. The molten cerium samples were then dropped into a copper block calorimeter contained in isothermal surroundings. The cerium data between 1400 and 1700/sup 0/K indicated a nonlinear heat content function as described by the equation: H/sub T/ -- H/sub 298/./sub 15/ = --0.01255 T/sup 2/ + 75.305 T -- 32,995.401 J/mol. The correlation coefficient for the curve fitting process was 0.81. The data between 1700 and 2500/sup 0/K indicated a linear heat content function as described by the equation: H/sub T/ - H/sub 298/./sub 15/ = (31.616 +- 0.596)(T - 1077) + (38,917.267 +- 575.049) J/mol. The average percent deviation between this and the experimental values was 0.67. Experimental heat contents were corrected for convection and radiation heat losses during the fall of the sample from the levitation chamber into the calorimeter. The maximum estimated error for the levitation calorimetry work was +-2.5 percent.

Liquid praseodymium heat content by levitation calorimetry

The high-temperature heat content of liquid praseodymium was measured experimentally by the levitation calorimetry technique. The samples, ranging in size from 0.5 to 1.5 g, were simultaneously levitated and heated by a radiofrequency generator in an argon-helium mixture prior to being dropped into a conventional copper block drop calorimeter. Corrections were made for the convection and radiation losses during the fall of the sample from the levitation chamber into the calorimeter. The praseodymium data, from 1460 to 2289K, were fitted by the following equation where the indicated errors represent the average deviation of the experimental value from the value predicted by the equation: H/sub T/ - H/sub 298/./sub 15/ = (41.57 +- 0.29) (T - 1208) + (41733 +- 197) J/mol. (auth)

The high-temperature enthalpy of liquid lanthanum by levitation calorimetry

A levitation calorimetry technique was used to measure the enthalpy of liquid lanthanum from 1250 to 2420 K. Lanthanum samples ranging from 0.5 to 2 g were levitated and melted in an inert atmosphere using a 15 kV A, 450 kHz radio-frequency generator. The results, in the temperature range 1250 to 2420 K, were fitted by the following equation where the indicated errors were obtained from the average deviation of the results from the values predicted by the equation: {H(T)−H(298.15 K)} J mol −1 = (32.77±0.18)(T K)−(2289±343) Convection and radiation heat losses during the fall of the sample from the levitation chamber into the calorimeter amounted to 0.5 to 2.0 per cent and 2 to 5 per cent of the total enthalpy respectively. The levitation calorimetry method is estimated to have a maximum error of ±2.5 per cent.

The high temperature heat content of liquid yttrium by levitation calorimetry

A 15 kva, 450 khz radio-frequency generator was used to levitate and melt yttrium samples ranging from 0.5 to 2 g in an inert atmosphere before being dropped into a copper block drop calorimeter contained in isothermal surroundings. The yttrium data were fitted by the following equation where the indicated errors were obtained from the average deviation of the data from the values predicted by the equation:HT−H298.15 = [39.725 ± 0.544] (T − 1799) + [64,116.655 ±163.285] J/mol for 1799 <T < 2360 K. Heat contents measured with the system were corrected for convection and radiation heat losses during the fall of the sample from the levitation chamber into the calorimeter. The maximum estimated error for the levitation calorimetry method was ± 2.5 pct.

Levitation calorimetry. IV. Thermodynamic properties of liquid cobalt and palladium

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLevitation calorimetry. IV. Thermodynamic properties of liquid cobalt and palladiumJ. A. Treverton and J. L. MargraveCite this: J. Phys. Chem. 1971, 75, 24, 3737–3740Publication Date (Print):November 1, 1971Publication History Published online1 May 2002Published inissue 1 November 1971https://doi.org/10.1021/j100693a018RIGHTS & PERMISSIONSArticle Views118Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (383 KB) Get e-Alerts

Thermodynamic properties by levitation calorimetry III. The enthalpies of fusion and heat capacities for the liquid phases of iron, titanium, and vanadium

A levitation calorimeter has been used to determine the thermodynamic properties of liquid titanium, vanadium, and iron over the temperature ranges: 1969 to 2315K, 2205 to 2638 K, and 1804 to 2142 K, respectively. In addition, emissivity values for the liquid metal surfaces have been determined. A summary of the results obtained is presented below. Titanium Vanadium Iron Δ H m / cal mol − 1 3161 ± 120 4136 ± 170 3307 ± 70 Δ S m / cal K − 1 mol − 1 1.63 ± 0.06 1.90 ± 0.08 1.83 ± 0.04 C p / cal K − 1 mol − 1 10.87 ± 0.41 11.65 ± 0.36 10.29 ± 0.29 ( e l , T m , λ = 0.65 μm ) 0.477 ± 0.027 0.400 ± 0.019 0.378 ± 0.006