Investigation of electron beam melting and refining of titanium and tantalum scrap

Vutova, Katia; Vassileva, Vania; Koleva, Elena; Georgieva, Elka R.; Mladenov, G.; Mollov, Dimitar; Kardjiev, M.

doi:10.1016/j.jmatprotec.2010.02.020

Cited by 49 publications

(25 citation statements)

References 2 publications

(7 reference statements)

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“…In Fig.1, a vertical cross-section of the temperature field is shown for P = 11kW in the 442 nd second of the heating. The cluster analysis shows that the criterion (10) is minimized for P b = 11kW and confirms the result from the statistical approach [12]. The proposed optimization technique does not need experimental data for chemical analysis of the impurities' concentrations like the approach in [12], which is an important advantage of the optimization method described in this paper.…”

Section: Resultssupporting

confidence: 76%

“…Experiments for EBMR of Ti ingots of length H = 100mm and diameter 2R = 60mm are made for various values of the beam power P b and casting velocity V and experimental data about the concentration of some of the metal's impurities are obtained [12]. Statistical approach, based on experimental data about chemical analysis, is applied and optimal process conditions by minimization of all impurities concentrations are obtained -P b = 11.25kW, V = 6mm/min, F = 7.37min for focused electron beam with r b = 10mm.…”

Section: Resultsmentioning

confidence: 99%

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Optimization method for electron beam melting and refining of metals

Donchev

Vutova

2014

J. Phys.: Conf. Ser.

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Abstract. Pure metals and special alloys obtained by electron beam melting and refining (EBMR) in vacuum, using electron beams as a heating source, have a lot of applications in nuclear and airspace industries, electronics, medicine, etc. An analytical optimization problem for the EBMR process based on mathematical heat model is proposed. The used criterion is integral functional minimization of a partial derivative of the temperature in the metal sample. The investigated technological parameters are the electron beam power, beam radius, the metal casting velocity, etc. The optimization problem is discretized using a non-stationary heat model and corresponding adapted Pismen-Rekford numerical scheme, developed by us and multidimensional trapezional rule. Thus a discrete optimization problem is built where the criterion is a function of technological process parameters. The discrete optimization problem is heuristically solved by cluster optimization method. Corresponding software for the optimization task is developed. The proposed optimization scheme can be applied for quality improvement of the pure metals (Ta, Ti, Cu, etc.) produced by the modern and ecologicalfriendly EBMR process. IntroductionElectron Beam Melting and Refining (EBMR) is a method in the special electrometallurgy for production of pure metals and alloys and new materials fabrication by scrap recycling [1][2][3].The EBMR process of metals and alloys is accomplished in vacuum chamber using electron beams as a heating source. The raw material is melted, refined and re-solidified in a watercooled crucible. The electrons fall on the front side of the feeding material and heat it. The molten metal as drops fall into the crucible. The top surface of the molten metal in the crucible is also heated by the e-beam [1][2][3]. Due to especially difficulties to acquire real time data for the processes in the liquid pool, the successful application and optimization of EBMR depends on the adequate mathematical modeling of the heat transfer processes. This allows to make a study of the influence of the regime parameters and the limiting factors. The most important information that is needed is about the temperature field in the metal ingot during EBMR which can't be precisely evaluated experimentally.In [4][5][6][7] developed stationary and non-stationary heat transfer models are presented and implemented. The non-stationary model, discretized by a modified Pismen-Rekford scheme [6,8], and the corresponding computer program gives opportunity for simulation of the EBMR process and gaining information about the dynamics of the input and output steams,

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Optimization method for electron beam melting and refining of metals

Donchev

Vutova

2014

J. Phys.: Conf. Ser.

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“…This technology is mainly used for melting and refining of refractory and reactive metals, such as tantalum [9,10], niobium [6,11], ruthenium [12], molybdenum [13], iridium [14], vanadium, titanium [7,[15][16][17], etc., and their alloys. This method plays an important role in the production of ultrapure sputtering target materials and electronic alloys [9,12], in metal regeneration from waste products [3,18], in the metallurgical-grade silicon purification for the photovoltaic industry [8,[19][20][21], etc.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, theoretical investigation and application of different approaches-numerical, statistical, heuristic, etc. [4,18,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]-are essential for the understanding and optimization of e-beam melting and refining technology. Consequently, modeling and mathematical optimization of the process parameters are important and key to improving the quality of the obtained pure metal, depending on the concrete characteristic requirements.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Tantalum Recycling by Electron Beam Melting

Vutova

Vassileva

Koleva

et al. 2016

Metals

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Abstract:Investigations are carried out and obtained experimental and theoretical data for tantalum scrap recycling by electron beam melting (EBM) is presented in this paper. Different thermal treatment process conditions are realized and results are discussed. A chemical analysis is performed and refining mechanisms for electron beam (EB) refining of Ta are discussed. For the performed experiments the best purification of Ta (99.96) is obtained at 21.6 kW beam power for a melting time of 3 min. A statistical approach is applied for estimation of the material losses and the liquid pool characteristics based on experimentally-obtained data. The aim is to improve the EBM and choosing optimal process conditions, depending on the concrete characteristic requirements. Model-based quality optimization of electron beam melting and refining (EBMR) processes of Ta is considered related to the optimization of the molten pool parameters, connected to the occurring refining processes, and to minimal material losses. Optimization of the process of EBM of Ta is based on overall criteria, giving compromised solutions, depending on the requirements concerning the quality of the performed products. The accumulated data, the obtained results, and the optimization statistical approach allow us to formulate requirements on the process parameters.

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“…10) On the other hand, little research on the refining of Ru by EB melting has thus far been reported. Schriempf 11) reported that an EB zone refining process could be used to produce a final 5N-grade-purity Ru rod from commercial Ru powder that was 99.9 mass% pure.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Purity Evaluation of 5N-Grade Ruthenium by Electron Beam Melting

Lee

Park

et al. 2012

Mater. Trans.

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In this study, we carried out an electron beam (EB) melting purification process to obtain a 5N-grade high-purity Ru ingot from commercial Ru powder. The first step was to primarily sinter Ru powder compact by means of vacuum heat treatment at 1,773 K. Vacuum sintering was employed to ensure a high vacuum condition during EB melting by the removal of remaining gaseous elements between the compact powders. The second step was to obtain Ru ingots by EB melting of the sintered Ru compact. The purity of the Ru raw powder was 99.962 mass% and the purity of a premelted Ru button ingot obtained by EB melting was 99.9873 mass%. The purities of the respective Ru button ingots remelted for 2 and 4 min were 99.9988 and 99.9992 mass%, respectively. As a result, the sum of metallic impurities in the Ru ingot refined for 6 min was 5.3 mass ppm and the purity of the ingot considerably increased up to 99.9995 mass%, which means that a 5N-grade high-purity Ru ingot can be obtained by the EB melting purification process. Furthermore, the EB-melted Ru ingot showed an excellent ability to remove interstitial impurities.

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Investigation of electron beam melting and refining of titanium and tantalum scrap

Cited by 49 publications

References 2 publications

Optimization method for electron beam melting and refining of metals

Optimization method for electron beam melting and refining of metals

Investigation of Tantalum Recycling by Electron Beam Melting

Preparation and Purity Evaluation of 5N-Grade Ruthenium by Electron Beam Melting

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