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.

scholarly journals Clinopyroxene Solid Solutions in the CaMgSi2O6 – Ca0,5AlSi2O6 Cross-Section at High P-T Parameters

2020 ◽  
Vol 34 ◽  
pp. 37-54
Author(s):  
S. V. Banushkina ◽  
◽  
A. I. Turkin ◽  
A. I. Chepurov ◽  
◽  
...  
Keyword(s):  
Cross Section ◽  
Solid Solutions ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Experimental Investigations ◽  
Electric Resistance ◽  
Resistance Furnace ◽  
Mineral Association ◽  
Electric Resistance Furnace ◽  
Piston Cylinder

Clinopyroxenes (Cpx) are one of the main rock-forming minerals, but stoichiometry of their compositions was called into question. In particular, an idea of hypothetical calcium molecule Eskola (CaEs, Ca0,5AlSi2O6) existence was expressed. This minal has structure vacancy and silica excess. Numerous experimental investigations in CMAS-system (CaO-MgO-Al2O3-SiO2) have showed that the question of non-stoichiometric Cpx existence remains open. This paper presents the results of an experimental study of the diopside Di (CaMgSi2O6) – calcium molecule Eskola CaEs (Ca0,5AlSi2O6) cross-section in the CMAS-system. The experiments were carried out in the following pressure and temperature range: P=10-4 – 3,0 GPa; T=966 – 15250C. Experiments at atmospheric pressure (10-4 GPa) were performed on a vertical shaft electric resistance furnace; high-pressure ones were performed on a "piston-cylinder" type apparatus. Samples obtained were analyzed using electron microprobe (EMP), scanning electron microscope (SEM) and Raman spectrometer. Depending on the P-T conditions, the samples contain the following phases: anorthite An, garnet Grt, diopside Di, clinopyroxene Cpx, quartz Qtz (tridymite Tr – for experiments at atmospheric pressure), and glass L. The data array on the composition of clinopyroxenes crystallized in this cross-section with diopside in various associations is generalized and supplemented. Clinopyroxenes were found to form quaternary solid solutions of diopside Di (CaMgSi2O6) – enstatite En (Mg2Si2O6) – calcium molecule Tschermak CaTs (CaAl2SiO6) – calcium molecule Eskola CaEs (Ca0,5AlSi2O6). The CaTs and CaEs minals contents are positively correlated with the amount of aluminum in clinopyroxene, and this relationship is particularly pronounced for CaTs. It is confirmed that clinopyroxenes in this cross-section can contain an excess of silica at both atmospheric and high pressures. Apparently, the cation vacancy that exists in pyroxene structure can participate in ordering processes. As a result the pyroxenes of another structure (not diopside – C2/c-symmetry) can be crystallized from total compositions in the Di-CaEs cross-section. Additional research is needed to support this hypothesis. Besides, at present investigation it was not possible to establish an unambiguous relationship between the Cpx composition and P-T-parameters, since it is also associated with both the mixture initial composition and the mineral association. Further experiments are required to justify any geothermobarometric dependence.

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.

On the problem of the phase relations in the B-BN system at high pressures and temperatures

2009 ◽  
Vol 31 (1) ◽  
pp. 1-6 ◽  
Author(s):  
V. L. Solozhenko ◽  
O. O. Kurakevych ◽  
V. Z. Turkevich ◽  
D. V. Turkevich
Keyword(s):  
High Pressures ◽  
Phase Relations ◽  
High Pressures And Temperatures

Phase relations in the Fe-P system at high pressures and temperatures from ab initio computations

2020 ◽  
Vol 40 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Nursultan E. Sagatov ◽  
Pavel N. Gavryushkin ◽  
Maksim V. Banayev ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov
Keyword(s):  
Ab Initio ◽  
High Pressures ◽  
Phase Relations ◽  
P System ◽  
High Pressures And Temperatures ◽  
Ab Initio Computations

Thermo-elastohydrodynamic simulation of the piston-cylinder contact in high-pressure pumps at 3000 bar

2019 ◽  
Vol 71 (5) ◽  
pp. 702-705
Author(s):  
Ömer Özdemir ◽  
Felix Fischer ◽  
Adrian Rienäcker ◽  
Katharina Schmitz
Keyword(s):  
High Pressure ◽  
Thermal Stresses ◽  
Test Bench ◽  
High Pressures ◽  
Elastohydrodynamic Lubrication ◽  
Simulation Method ◽  
Pressure Effects ◽  
High Pressure Pump ◽  
Content Type ◽  
Piston Cylinder

Purpose The purpose of this paper is to show these effects in an abstracted micro gap test bench. Because of stronger emission laws, the ambition to raise the rail pressure in common-rail systems from the current 2500 bar to 3000 bar is a given. The pressure increase will allow fine atomization of fuel and therefore more efficient combustion. But within the technical system of the high-pressure pump, stronger thermal stresses of the piston–cylinder contact are expected. A pressure drop from such a high level causes high temperature gradients due to energy dissipation. Design/methodology/approach For a detailed examination, the critical piston–cylinder contact has been investigated in an abstracted test bench with a flat parallel gap and an equivalent thermo-elastohydrodynamic simulation model. Findings The simulation results show good accordance to the measurements of pressures, temperatures and leakages for pressures up to 3000 bar. Comparison with elastohydrodynamic lubrication results outlines the need to consider temperature and pressure effects viscosity and solid deformation for the simulation and design of tribological contacts at high pressures. Originality/value This paper describes a simulation method with high accuracy to investigate tribological contacts considering temperature effects on solid structures and the fluid film. The thermo-elastohydrodynamic lubrication simulation method is valid not only for piston–cylinder contacts in high-pressure pumps but also for journal bearings in combustion engines.

scholarly journals Materials Chemistry under High Pressures – Some Recent Aspects

2006 ◽  
Vol 61 (12) ◽  
pp. 1457-1470 ◽  
Author(s):  
Gérard Demazeau ◽  
Hubert Huppertz ◽  
José A. Alonso ◽  
Rainer Pöttgen ◽  
Emilio Moran ◽  
...  
Keyword(s):  
Thermodynamic Parameters ◽  
High Pressures ◽  
Structural Transformations ◽  
Chemical Bonds ◽  
Materials Chemistry ◽  
Novel Materials ◽  
Solid Media ◽  
Main Factors ◽  
Soft Processes ◽  
Synthesis Of Materials

Among the thermodynamic parameters governing the preparation of novel materials, temperature (T) and pressure (p) play an important role. In Materials Chemistry, the synthesis of materials needs energy in order to enhance the diffusion of atoms to the equilibrium positions required by the specific structure and to induce the formation of chemical bonds. The comparison of the energy conveyed by both parameters (p and T) underlines that high pressures can be associated - in liquid or solid media - with soft processes. Consequently this paper describes the main factors induced by the parameter pressure that are able to support new structural forms or generate novel materials. Two different approaches are presented: (i) for a given composition with characteristic chemical bonds, high pressures can induce structural transformations, (ii) high pressures lead to the formation of novel materials from different precursors through the formation of new chemical bonds.

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