Analysis of the Thermal Transfers in a VASM Crucible: Electron Beam Melting Experiment and Numerical Simulation

A description of the Vacuum Arc Skull Melting (VASM) process is presented showing its particularly complex features because of the mixing of porous raw materials with the dense remelted metal as well as the very high temperature and the highly transient nature of the process. This paper presents a 3D transient mathematical modelling of the heat transport with the aim of bringing a better understanding of the thermal behavior of the material into the crucible during a melting cycle. The model takes into account the heat input provided by the incoming metal thanks to an adaptive meshing, as well as the latent heat of solidification and the radiative heat transfers. An experimental validation of the model is presented where an electron beam heating source mimics the heat effect of the arc thanks to an excellent guidance of the beam over the melt surface. A comparison between the measured and calculated temperatures of a steel load is reported and reveals a satisfactory agreement. With very few adjustments, concerning mainly heat radiation at the top surface of metal into the crucible, the numerical model appears to be an efficient numerical tool to simulate the VASM process at the industrial scale.

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Results from energetic electron beam metal vapor vacuum arc and Z-discharge plasma metal vapor vacuum arc: Development of new sources of intense high charge state heavy-ion beams

Review of Scientific Instruments ◽

10.1063/1.1148738 ◽

1998 ◽

Vol 69 (2) ◽

pp. 798-800 ◽

Cited By ~ 14

Author(s):

A. Hershcovitch ◽

B. M. Johnson ◽

F. Liu ◽

A. Anders ◽

I. G. Brown

Keyword(s):

Electron Beam ◽

Charge State ◽

Discharge Plasma ◽

Energetic Electron ◽

Metal Vapor ◽

Heavy Ion ◽

Ion Beams ◽

High Charge State ◽

Vacuum Arc ◽

High Charge

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Вольт-амперные характеристики начальной стадии дугового разряда в высоковольтном вакуумном диоде

Письма в журнал технической физики ◽

10.21883/pjtf.2019.12.47916.17799 ◽

2019 ◽

Vol 45 (12) ◽

pp. 33

Author(s):

С.Г. Давыдов ◽

А.Н. Долгов ◽

А.В. Корнеев ◽

Р.Х. Якубов

Keyword(s):

Electron Beam ◽

High Voltage ◽

Arc Discharge ◽

Ion Beam ◽

Vacuum Diode ◽

Vacuum Arc ◽

Ion Acceleration ◽

Plasma Cloud ◽

Initial Stage ◽

Instability Development

AbstractThe process of electron instability development and propagation of a cathode electron beam and anomalous ion beam, followed by outburst of current in the initial stage of arc discharge was observed in rarefied plasma cloud of high-voltage vacuum diode. These events are consistent with the model of anomalous ion acceleration in interelectrode plasma at the spark stage of vacuum arc discharge.

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Analysis of the Plasma Recycling Process of Radioactive Waste

Nuclear and Radiation Safety ◽

10.32918/nrs.2019.1(81).04 ◽

2019 ◽

pp. 23-29

Author(s):

M. Semerak ◽

S. Lys ◽

T. Kovalenko

Keyword(s):

Radioactive Waste ◽

Silicon Oxide ◽

Raw Materials ◽

Shaft Furnace ◽

Plasma Heating ◽

Plasma Processing ◽

Radioactive Wastes ◽

Heating Source ◽

Long Term Storage ◽

Plasmochemical Reactor

The possibility of the plasma processing of low-level or intermediatelevel radioactive wastes in the reactor equipped with arc plasmatrons is shown. The reactor design for the plasma processing of the radioactive wastes that allows promoting the efficiency of the plasma processing of the radioactive wastes (RAW) by the increasing of the speed and the intensity of the plasma pyrolysis is proposed. The various methods for RAW preparation, dosage and supply into the plasmochemical reactor have been investigated. The waste which is supplied to the reactor can be in various aggregate states (solid, liquid or gaseous) depending on which different kinds of preparation, dosage, and supply of RAW materials to the plasmochemical reactor are used. The solid waste must be ground for increasing of the phase separation surface. The degree of grinding of the wastes depends on their further reprocessing. The reactor allows processing of the mixed-type radioactive waste, which includes both combustible and non-combustible components. The wastes can be packed or ground up. The selected technological regimes should provide temperature from 1500 °C in the melting chamber to 250 °C in the upper part in the pyrogas exit zone to prevent the flow-out of volatile compounds of a series of radionuclides and heavy metals from the furnace and to process the waste and merge slag melt without adding of fluxes. The fused slag is a basaltiform monolith, where the content of aluminum oxide reaches 28%; silicon oxide up to 56%; sodium oxide from 2.5 to 11 %. The resulting radioactive slag is extremely resistant to the chemical influence. The pyrogas produced in the shaft furnace will have a heating value of about 5 MJ/nm3. This allows, after initial heating by plasmatron, maintaining the required temperature in the combustion chamber due to the heat released during combustion of the pyrogas, when the plasma heating source is switched off, and burning the resin and soot effectively. It is proved that the plasma technology for RAW reprocessing allows a significant reduction in waste volumes and waste placement for long-term storage with the most efficient use of storage facilities.

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The electron beam as a heating source

Vacuum ◽

10.1016/0042-207x(66)90462-3 ◽

1966 ◽

Vol 16 (10) ◽

pp. 555

Keyword(s):

Electron Beam ◽

Heating Source

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Optimization of the heating source in electron beam welding of zirconium pipes

Welding International ◽

10.1080/09507116.2012.715909 ◽

2013 ◽

Vol 27 (4) ◽

pp. 300-303 ◽

Cited By ~ 2

Author(s):

A. N. Semenov ◽

M. I. Plyshevskii ◽

V. P. Gordo ◽

N. S. Rassoshkina ◽

V. V. Melyukov ◽

...

Keyword(s):

Electron Beam ◽

Electron Beam Welding ◽

Heating Source

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Ti6Al4V Parts Produced by Electron Beam Melting: Analysis of Dimensional Accuracy and Surface Roughness

Journal of Advanced Manufacturing Systems ◽

10.1142/s0219686720500067 ◽

2020 ◽

Vol 19 (01) ◽

pp. 107-130 ◽

Cited By ~ 2

Author(s):

R. Borrelli ◽

S. Franchitti ◽

C. Pirozzi ◽

L. Carrino ◽

L. Nele ◽

...

Keyword(s):

Surface Roughness ◽

Electron Beam ◽

Additive Manufacturing ◽

Electron Beam Melting ◽

Complex Shape ◽

Electron Beam Welding ◽

Raw Materials ◽

Dimensional Accuracy ◽

High Energy ◽

Quality Certification

Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.

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