scholarly journals Finite element analysis of electroresistive heating of a high pressure apparatus for studying the solubility of GaN in Fe

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Oleksiy Liudvichenko ◽  
Oleksandr Anisin ◽  
Oleksandr Lyeshchuk ◽  
Vitaliy Shchydlovskyi
Keyword(s):  
High Pressure ◽  
Gallium Nitride ◽  
High Pressures ◽  
Thermal State ◽  
Control Point ◽  
Experimental Studies ◽  
Temperature Fields ◽  
Element Analysis ◽  
Advantages And Disadvantages ◽  
High Pressure Apparatus

The advantages and disadvantages of methods for gallium nitride crystals production are considered. The convergence of the solution of the problem of electroresistive heating at determination of a thermal condition of the high pressure apparatus cell is investigated. The thermal state of the high pressure apparatus cell used to determine the solubility of gallium nitride in iron has been modeled and investigated. It is determined that the combined discretization with the use of triangular and quadrangular elements allows to reduce the time of solving the coupled problem of electrical and thermal conductivity under these conditions. The results of calculations are presented by steady temperature fields in various elements of the device. It was obtained that at the temperature in the cell control point of 1800 °С its axial difference in the volume of the investigated sample of iron was 62 °С , the maximum difference was 156 °С. The simulated cell configuration and the heating conditions defined for it are acceptable for experimental studies of the solubility of GaN in contact with Fe under conditions of high pressures and temperatures.

Formation of two crystal modifications of Fe7C3−x at 5.5 GPa

2019 ◽  
Vol 52 (6) ◽  
pp. 1378-1384
Author(s):  
Sergey Gromilov ◽  
Anatoly Chepurov ◽  
Valeri Sonin ◽  
Egor Zhimulev ◽  
Aleksandr Sukhikh ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Experimental Studies ◽  
X Ray Diffraction ◽  
High Iron Content ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Micro Analysis ◽  
Crystal Modifications ◽  
High Pressure Apparatus

The Fe–C system, which is widely used to grow commercial high-pressure–high-temperature diamond monocrystals, is rather complicated due to the formation of carbides. The carbide Fe3C is a normal run product, but the pressure at which Fe7C3 carbide becomes stable is a subject of discussion. This paper demonstrates the synthesis of Fe7C3 carbide and its detailed study using single-crystal and powder X-ray diffraction, as well as electron probe micro-analysis and scanning electron microscopy. The experiments were performed using a multiple-anvil high-pressure apparatus of `split-sphere' (BARS) type at a pressure of 5.5 GPa and a temperature of 1623 K. Our results show that in the Fe–C system, in addition to diamond, a phase that corresponds to the Fe7C3 carbide was synthesized. This means that both carbides (Fe7C3 and Fe3C) are stable at 5.5 GPa. Two crystal phases are described, Fe14C6 and Fe28C12−x . Fe14C6 is based on the well known rhombic structure of Fe7C3, while Fe28C12−x has a different packing order of Fe6C polyhedrons. The results obtained in this study should be taken into account when synthesizing and growing diamond at high pressures and temperatures in metal–carbon systems with a high iron content, as well as when conducting experimental studies on the synthesis of diamond directly from carbide.

Design and Analysis of a High Pressure Apparatus

1980 ◽  
Vol 102 (3) ◽  
pp. 633-640
Author(s):  
K. C. Rolle ◽  
J. N. Crisp ◽  
A. N. Palazotto
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Phase Diagrams ◽  
High Pressures ◽  
Equilibrium Phase ◽  
Original Design ◽  
Piston Displacement ◽  
Crude Analysis ◽  
High Pressure Apparatus

In the determination of equilibrium phase diagrams, i.e., pressure volume-temperature relations for lubricants at pressures up to 2800 MPa and temperatures of 378K, one must carry out a highly sophisticated design of a high pressure apparatus. In 1935 Bridgman designed a piston-displacement device and measured the compressibility of numerous materials at high pressures. However, in order to obtain accurate equilibrium phase diagrams for lubricants, Bridgman’s relatively crude analysis must be considerably refined. The authors have extended this original design using finite element techniques to accurately correct pertinent measurements which are in turn incorporated into the expressions used in determining the pressure-volume temperature relations of lubricants.

Numerical Analysis of High Pressure Cold Bend Pipe to Investigate the Behaviour of Tension Side Fracture

2012 ◽  
Author(s):  
Celal Cakiroglu ◽  
Amin Komeili ◽  
Samer Adeeb ◽  
J. J. Roger Cheng ◽  
Millan Sen
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Internal Pressure ◽  
Experimental Studies ◽  
Element Model ◽  
Combined Loading ◽  
Element Analysis ◽  
Bend Pipe ◽  
Bending Load ◽  
Bending Loads

The cold bend pipelines may be affected by the geotechnical movements due to unstable slopes, soil type and seismic activities. An extensive experimental study was conducted by Sen et al. in 2006 to understand the buckling behaviour of cold bend pipes. In their experiments, it was noted that one high pressure X65 pipe specimen failed under axial and bending loads due to pipe body tensile side fracture which occurred after the development of a wrinkle. The behaviour of this cold bend pipe specimen under bending load has been investigated numerically to understand the conditions leading to pipe body tension side fracture following the compression side buckling. Bending load has been applied on a finite element model of the cold bend by increasing the curvature of it according to the experimental studies conducted by Sen [1]. The bending loads have been applied on the model with and without internal pressure. The distribution of the plastic strains and von Mises stresses as well as the load–displacement response of the pipe have been compared for both load cases. In this way the experimental results obtained by Sen [1] have been verified. The visualization of the finite element analysis results showed that pipe body failure at the tension side of the cold bend takes place under equal bending loads only in case of combined loading with internal pressure.

Finite Element Analysis of a Compressor Housing Used in High Pressure Refrigeration System

2007 ◽  
Author(s):  
Raul Bosco ◽  
Ricardo Alexandre Maciel ◽  
Miguel Mattar Neto ◽  
Carlos Alexandre J. Miranda
Keyword(s):  
High Pressure ◽  
Structural Integrity ◽  
High Pressures ◽  
Cost Effective ◽  
Design Approach ◽  
Refrigeration System ◽  
Original Design ◽  
Element Analysis ◽  
Compression Mechanism ◽  
Development Approach

In the design of compressors running with high pressure refrigerants, safety aspects must be a mandatory concern. Moreover, when dealing with high pressure levels, compressor components have their original design adapted to withstand such a high pressures, particularly acoustical mufflers, external housing, and compression mechanism. Regarding the external housing, the design approach goes beyond acoustical and aesthetics features as mostly observed in current refrigerating compressors. In order to safety enclose the compression mechanism the application of a proper design methodology is mandatory to safeguard the structural integrity of both the compressor external housing and the whole refrigerating system. Looking for acceptable, cost effective safety factors, a simultaneous design approach including advanced structural mechanics techniques, experimentation, safety Codes revision, and Computer Aided Engineering (CAE) tools application is mandatory. The aim of this work is to present a new development approach, concerning structural design of a compressor housing used in high pressure refrigeration system. Numerical and experimental results will be compared among each other aiming to evaluate some ASME Codes criteria and design procedures.

scholarly journals High-pressure diffraction studies of molecular organic solids. A personal view

2007 ◽  
Vol 64 (1) ◽  
pp. 218-231 ◽  
Author(s):  
Elena V. Boldyreva
Keyword(s):  
High Pressure ◽  
Solid State ◽  
High Pressures ◽  
Experimental Studies ◽  
Personal View ◽  
Organic Solids ◽  
High Pressure Studies

This paper discusses the trends in the experimental studies of molecular organic solids at high pressures by diffraction techniques. Crystallization of liquids, crystallization from solutions and solid-state transformations are considered. Special attention is paid to the high-pressure studies of pharmaceuticals and of biomimetics.

Finite element analysis and experiment on high pressure apparatus with split cylinder

2017 ◽  
Vol 37 (3) ◽  
pp. 377-388
Author(s):  
Liang Zhao ◽  
Mingzhe Li ◽  
Yunfei Yang ◽  
Bolong Wang ◽  
Yi Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Pressure ◽  
Element Analysis ◽  
High Pressure Apparatus

Hochdruckumwandlungen von Cer(III)Orthovanadat(V), CeVO4 / High-Pressure Transformations of Cerium(III) Orthovanadate(V), CeVO4

1990 ◽  
Vol 45 (5) ◽  
pp. 598-602 ◽  
Author(s):  
Klaus-Jürgen Range ◽  
Helmut Meister ◽  
Ulrich Klement
Keyword(s):  
High Pressure ◽  
Triple Point ◽  
High Pressures ◽  
Its Region ◽  
Normal Pressure ◽  
Crystal Data ◽  
High Pressures And Temperatures ◽  
Zircon Type ◽  
High Pressure Apparatus

The polymorphism of CeVO4 was investigated at high pressures and temperatures in a Belttype high-pressure apparatus. In addition to the normal-pressure modification CeVO4— I with zircon-type structure two high-pressure modifications have been found, viz. monazite-type CeVO4—II and scheelite-type CeVO4—III. CeVO4—II is stable between 1 bar and 30 kbar at 1300 °C. Its region of existence decreases rapidly at lower temperatures. From the observed p,T-relations for the I-II and I-III transformations a triple point CeVO4—I,II,III at about 27 kbar, 500 °C can be estimated. For kinetic reasons, however, the experimental determination of phase relations becomes difficult at temperatures below 600 °C.The crystal structures of CeVO4— I and —II have been refined from single-crystal data. Crystallographic data for the three modifications are given and discussed (CeVO4—I: I 41/amd, a = 7.383(1)Å, c = 6.485(1)Å, Z = 4; CeVO4—II: P21/n, a = 7.003(1)Å, b = 7.227(1)Å, c = 6.685(1)Å, β = 105.13(1)°, Z = 4; CeVO4—III: I 41/α, a = 5.1645(2)Å, c = 11.8482(7)Å, Z = 4).

Synchrotron Moessbauer Spectroscopy and Resistivity Studies of Iron Oxide Under High Pressure

2006 ◽  
Vol 987 ◽  
Author(s):  
Viktor V. Struzhkin ◽  
Mikhail I. Eremets ◽  
Ivan M. Eremets ◽  
Jung-Fu Lin ◽  
Wolfgang Sturhahn ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
High Pressures ◽  
Structural Phase ◽  
Experimental Studies ◽  
Magnetic Interactions ◽  
Diamond Anvil

AbstractThe strong electron correlations play a crucial role in the formation of a variety of electronic and magnetic properties of the transition metal oxides. In strongly correlated electronic materials many theoretical predictions exist on pressure-induced insulator-metal transitions, which are followed by a collapse of localized magnetic moments and by structural phase transitions [1]. The high-pressure studies provide additional degree of freedom to control the structural, electronic, optical, and magnetic properties of transition metal oxides. With the development of the high-pressure diamond-anvil-cell technique the experimental studies of such transitions are now possible with the advanced synchrotron techniques. In our studies, the iron monooxide Fe0.94O was studied under high pressures up to 200 GPa in diamond anvil cells. The single crystals enriched with Fe57 isotopes have been prepared for nuclear resonance measurements. The results of synchrotron Mössbauer spectroscopy (nuclear forward scattering -NFS), and electro-resistivity measurements suggest a complicated scenario of magnetic interactions governed by band-broadening effects.

scholarly journals Features of the internal structure of high-pressure metal-diamond composites

2020 ◽  
pp. 17-29
Author(s):  
Ilya Ishutin ◽  
◽  
Aleksei Chepurov ◽  
Egor Zhimulev ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Iron Carbide ◽  
Iron Alloy ◽  
Metal Component ◽  
Industrial Synthesis ◽  
Diamond Crystals ◽  
High Pressure Apparatus ◽  
Alloy Iron ◽  
Intergranular Space

In the present work, composites were obtained by sintering a metal-diamond charge at a pressure of 4 GPa and a temperature of 1300°C. the experiments were carried out on a high-pressure apparatus of the split sphere “bars” type. Synthetic microcrystals of industrial synthesis were used as a diamond. The initial metal component for the experiments was copper and iron. it was shown that when sintering at high pressure, diamond crystals are tightly packed in the composite, while the metal phase completely fills the intergranular space, acting as a matrix. chemical analysis of the metal component of the samples revealed the presence of the following phases: copper-iron alloy, iron oxide and iron carbide. the results obtained indicate that several processes occur simultaneously in the diamond-copper-iron-oxygen system at high pressures and temperatures, which can significantly affect the characteristics of the resulting composite as a whole.

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