scholarly journals An investigation of the dissociation pressures and melting points of the system Copper-cuprous oxide

1912 ◽  
Vol 87 (598) ◽  
pp. 524-534 ◽  
Keyword(s):  
Melting Point ◽  
Solid Solutions ◽  
Cuprous Oxide ◽  
Eutectic Temperature ◽  
Eutectic Point ◽  
Cooling Curve ◽  
Melting Points ◽  
Platinum Crucible ◽  
Dissociation Pressures

E. Heyn determined the melting points of mixtures of copper and cuprous oxide of compositions varying between 100 per cent. Cu and 88·24 per cent. Cu, 11·76 per cent. Cu 2 O. The results of his experiments are shown by the points marked + in fig. 1. These points fall on two curves intersecting at the eutectic point 1065° C., Cu 2 O 3·5 per cent., Cu 96·5 per cent. Heyn found that all his mixtures showed a halt in the cooling curve at this eutectic temperature, so that within the range of his experiments there is no evidence of the existence of solid solutions. C. N. Otin has lately published some experiments on the melting points of the system cuprous oxide-silica. He attempted to determine the melting point of cuprous oxide, but as some oxidation always took place in his experiments, and as he did not analyse the solid obtained (on account of having to remelt it to get it out of the platinum crucible), there is some doubt as to the actual composition of the substance of which he determined the melting point. The highest temperature at which he found a halt in the cooling curve was 1205° C.

Phase relations in the system anorthite–potassium-feldspar at 10 kbar with emphasis on their solid solutions

1989 ◽  
Vol 53 (371) ◽  
pp. 337-345 ◽  
Author(s):  
Y. Ai ◽  
D. H. Green
Keyword(s):  
Solid Solutions ◽  
High Pressures ◽  
Eutectic Temperature ◽  
Eutectic Point ◽  
Potassium Feldspar ◽  
Phase Relations ◽  
Maximum Solubility ◽  
Piston Cylinder ◽  
Solid Media ◽  
Mutual Solubilities

AbstractPhase relations in the binary system anorthite-K-feldspar at 10 kbar were studied with a solid-media piston cylinder apparatus. The eutectic character of this system is confirmed, with the eutectic point located at An30Kf70 (± 3 mol%), and 1215 ± 15°C, 10 kbar. The mutual solubilities between anorthite and K-feldspar at the solidus are greatly increased at 10kbar compared with those at 1 atm. The maximum solubility of K-feldspar in anorthite is c. 5% at 1 atm, c. 18% at 10 kbar; and that of anorthite in K-feldspar is c. 3% at 1 atm, c. 7% at 10 kbar. The increased solubilities are attributed to the increase in the eutectic temperature at high isostatic pressures. The results imply increased ternary feldspar solid solutions at high pressures and support the existence of homogeneous feldspars with extensive ternary composition under high-P, T and anhydrous conditions.

Possibility of predicting the existence of a complex compound in the NaF-Na2SO4 system

1983 ◽  
Vol 48 (9) ◽  
pp. 2437-2445
Author(s):  
Milan Malinovský ◽  
Jaroslava Vrbenská
Keyword(s):  
Melting Point ◽  
Binary System ◽  
Experimental Determination ◽  
Complex Compound ◽  
Thermal Dissociation ◽  
Experimental Studies ◽  
Eutectic Point ◽  
Melting Points ◽  
Binary Phase Diagrams ◽  
Thermodynamic Prediction

A method of thermodynamic prediction of the existence of a complex compound in the NaF-Na2SO4 binary system is described. On the basis of the knowledge of a part of liquids drawn in the vicinity of NaF melting point and coordinates of eutectic point, the conclusion was made that there exists the complex compound Na3FSO4 in the system. Its true and hypothetic melting points and the degree of its thermal dissociation were calculated. Further, the probable coordinates of a eutectic point in the Na3FSO4-Na2SO4 subsystem were found out. The calculated results were confronted with experimental determination; the agreement is very good. The method described can be useful for experimental studies of binary phase diagrams.

scholarly journals Structural stability, hardness, fracture toughness and melting points of Ta1-xHfxC and Ta1-xZrxC ceramics from first-principles

2020 ◽  
Author(s):  
Shuoxin Zhang ◽  
Shiyu Liu ◽  
Dali Yan ◽  
Qian Yu ◽  
Haitao Ren ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Melting Point ◽  
Solid Solutions ◽  
First Principles ◽  
Formation Energy ◽  
Elastic Moduli ◽  
Melting Points ◽  
Virtual Crystal Approximation ◽  
Lattice Constants ◽  
The Stability

Abstract We systematic investigated the influence of substitution of Hf and Zr atoms for Ta atoms in TaC using first-principles supercell (SC) method and virtual crystal approximation (VCA) methods, including the impurity formation energy, lattice constant, volume, elastic constants, elastic moduli, melting points, fracture toughness and density of states of the Ta 1-x Hfx C and Ta1-x Zrx C ceramics in the whole range of content 0≤ x ≤1. Our calculated results show that the stability of Ta 1-x Hf x C and Ta 1-x Zrx C increases with the increase of Hf and Zr content, and Ta1-x Zrx C is more stable than Ta1-x Hfx C at the same content of Hf and Zr. The lattice constants and volumes dilate with the increase of Hf and Zr content. Furthermore, Ta1-x Hfx C and Ta1-x Zrx C carbides are mechanically stable and brittle. The bulk modulus of Ta1-x Hfx C and Ta1-x Zrx C decreases with the increasing content of Hf and Zr. Moreover, the hardness, fracture toughness, and melting point of Ta1-x Hf x C and Ta1-x Zrx C solid solutions have the peak. In particular, Ta0.8Hf0.2C has the highest hardness, largest fracture toughness and highest melting temperature.

Predictions of Current Attachment at Thermionic Cathode for TIG Arcs

2008 ◽  
Vol 580-582 ◽  
pp. 319-322 ◽  
Author(s):  
Manabu Tanaka ◽  
Kentaro Yamamoto ◽  
Tashiro Shinichi ◽  
John J. Lowke
Keyword(s):  
Melting Point ◽  
Work Function ◽  
Atmospheric Pressure ◽  
The Other ◽  
Numerical Calculations ◽  
Maximum Temperature ◽  
Arc Plasma ◽  
Melting Points ◽  
Thermionic Cathode ◽  
Uniform Current

Study of current attachment at thermionic cathode for TIG arc at atmospheric pressure is attempted from numerical calculations of arc-electrodes unified model. The calculations show that the maximum temperature of arc plasma close to the cathode tip for W-2% ThO2 reaches 19,000 K and it is the highest value in comparison with the other temperatures for W-2% La2O3 and W-2% CeO2, because the current attachment at the cathode tip is constricted by a centralized limitation of liquid area of ThO2 due to its higher melting point. The calculations also show that, in cases of W- 2% La2O3 and W-2% CeO2, the liquid areas of La2O3 and Ce2O3 are widely expanded at the cathode tip due to their lower melting points and then produce uniform current attachments at the cathode. It is concluded that the current attachment at thermionic cathode is strongly dependent on work function, melting point and Richardson constant of emitter materials.

scholarly journals Predicting Melting Points of Biofriendly Choline-Based Ionic Liquids with Molecular Dynamics

2019 ◽  
Vol 9 (24) ◽  
pp. 5367 ◽  
Author(s):  
Karl Karu ◽  
Fred Elhi ◽  
Kaija Põhako-Esko ◽  
Vladislav Ivaništšev
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Ionic Liquids ◽  
Melting Point ◽  
Chemical Space ◽  
Mean Square ◽  
Melting Points ◽  
Simulation Based ◽  
Predicted Values ◽  
Dynamics Simulations

In this work, we introduce a simulation-based method for predicting the melting point of ionic liquids without prior knowledge of their crystal structure. We run molecular dynamics simulations of biofriendly, choline cation-based ionic liquids and apply the method to predict their melting point. The root-mean-square error of the predicted values is below 24 K. We advocate that such precision is sufficient for designing ionic liquids with relatively low melting points. The workflow for simulations is available for everyone and can be adopted for any species from the wide chemical space of ionic liquids.

scholarly journals Effects of Local Heating and Premelting in the Terminal Part of the e+ Track

2012 ◽  
Vol 733 ◽  
pp. 15-18 ◽  
Author(s):  
Dmitry Zvezhinskiy ◽  
Sergey V. Stepanov ◽  
Vsevolod Byakov ◽  
Bożena Zgardzińska
Keyword(s):  
Melting Point ◽  
Temperature Dependence ◽  
Local Heating ◽  
Bulk Temperature ◽  
Melting Points ◽  
Terminal Part ◽  
Slowing Down ◽  
Positronium Lifetime ◽  
Molten Region

The terminal part of the e+ track (the positron blob) is formed during ionization slowing down and subsequent ion-electron recombinations produced by a positron. It releases up to 1 keV of energy, which is converted into heat within few picoseconds. If a bulk temperature of a medium is below, but close enough to its melting point, some region of a substance may melt, yielding a peculiar temperature dependence of the lifetime (LT) spectra. We have estimated properties of the molten region with a help of macroscopic heat con- duction equation and suggested a model describing temperature dependence of the ortho- positronium lifetime in frozen methanol, ethanol, butanol and water close to their melting points.

scholarly journals An electric furnace for experiments in vacuo at temperatures

1912 ◽  
Vol 87 (598) ◽  
pp. 519-524
Keyword(s):  
High Temperatures ◽  
Electric Furnace ◽  
Cuprous Oxide ◽  
The Other ◽  
Resistance Furnace ◽  
Heterogeneous Equilibrium ◽  
Other Hand ◽  
Large Current ◽  
Dissociation Pressures ◽  
Reduction Of Oxides

This furnace was designed with a view to investigating at temperatures up to 1500° C. certain cases of heterogeneous equilibrium in which the equilibrium is defined by the pressure of the system. Instances are the dissociation of certain oxides, nitrides, and carbonates, and the reduction of oxides by carbon. The furnace could not be constructed of carbon, as carbon would react with some of the gases of which the pressure had to be measured, and also because it is almost impossible to remove the adsorbed gases from large quantities of carbon. Tubes of Royal Berlin porcelain in a platinum-wound resistance furnace may be used for temperatures up to 1200°, but at about this temperature they become soft, while the glaze runs and combines with any boat or other substance in the furnace. Tubes of silica are not suitable, because they are porous at high temperatures, and because they disintegrate owing to crystallisation taking place. It was decided to make the furnace of a platinum tube and to heat it by passing a large current through it. As some of the substances which it would be necessary to place in the furnace react with platinum, e. g . copper formed by the dissociation of cuprous oxide, it was necessary to make the furnace sufficiently large to take a boat or crucible of magnesia large enough to contain the reacting substance and thick enough to protect the tube. On the other hand, the tube ought to be as small as possible, in order that in determining the dissociation pressures all the charge should not be decomposed before the equilibrium is attained.

Melting Point of cis-1,4-Polybutadiene

1965 ◽  
Vol 38 (4) ◽  
pp. 921-923 ◽  
Author(s):  
J. C. Mitchell
Keyword(s):  
Melting Point ◽  
Thermodynamic Data ◽  
Experimental Techniques ◽  
Melting Point Depression ◽  
Melting Points ◽  
Heating Rates ◽  
Orientation Effects ◽  
Flory’S Theory

Abstract Melting point values for cis-1, 4-polybutadiene thus far reported in the literature have not exceeded +1° C. Varying values have been reported, both because of sample variations (differing amounts and distributions of chain imperfections) and because of variations in experimental techniques used to measure the melting point (in particular, varying heating rates). Some workers have extrapolated their data to predict that the melting point of a perfectly regular (100 per cent cis) cis-1, 4- polybutadiene (Tm°) would be close to +1° C. These extrapolations have been used to arrive at heats of fusion for the polymer from Flory's theory for melting point depression due to copolymeric impurities. One such value has been used in another investigation to estimate extents of crystallization from thermodynamic data. We wish to report observation of melting points several degrees higher than the assumed Tm° value of +1° C. Our experiments show that these higher values are not due to orientation effects.

A note on the melting-point of paraffins and fatty acids

1938 ◽  
Vol 34 (3) ◽  
pp. 459-464 ◽  
Author(s):  
E. B. Moullin
Keyword(s):  
Fatty Acids ◽  
Melting Point ◽  
Melting Temperature ◽  
Smooth Curve ◽  
Melting Points ◽  
Normal Paraffin ◽  
Simple Interpretation

The purpose of this note is to draw attention to a certain correspondence between the melting-points of normal paraffins and of fatty acids and to indicate a simple interpretation of this phenomenon. If the number of carbon atoms in a normal paraffin is plotted against the corresponding melting temperature, all the points in the diagram lie very close to a smooth curve drawn among them. If a similar diagram is made for the fatty acids, the points corresponding to an even number of carbon atoms lie on a curve of the same character as that found for paraffins. The points for an odd number of carbon atoms lie on a separate but similar curve, exemplifying the well-known alternation property.

PLASMA-ASSISTED VACUUM-COATING PROCESSES

1992 ◽  
Vol 06 (01) ◽  
pp. 1-24 ◽  
Author(s):  
GERHARD KIENEL
Keyword(s):  
Thin Films ◽  
Melting Point ◽  
Substrate Temperature ◽  
Important Variable ◽  
Coating Material ◽  
Melting Points ◽  
Coating Materials ◽  
Substrate Temperatures

For the properties of thin films produced in a vacuum the most important variable is the mobility of the particles in the course of condensation, which is dependent on the melting point of the coating material, the substrate temperature and the energy of the particles as they strike the substrate. Because of the generally higher particle energies in plasma-assisted processes, under comparable coating conditions lower substrate temperatures suffice than in the case of conventional evaporative coating. Especially with coating materials having higher melting points, compact films can be produced only if the particle energies are sufficiently high.

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