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Purification of Niobium by Multiple Electron Beam Melting for Superconducting RF Cavities
최국선,임재원,N. R. Munirathnam,김일호 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.3
In this work, purification of commercial grade (~99.9 %) niobium by multiple Electron Beam Melting (EBM) is reported. Impurity removal of carbon, oxygen, nitrogen, aluminum, iron, molybdenum, zirconium and tungsten in niobium matrix is presented as a part of the ingot melting stages. The minor material loss of niobium during melting is attributed to the amount of decarburization based on the ratio of initial and critical content of oxygen to carbon. The analysis of nearly 60 impurity elements in niobium was carried out by glow discharge mass spectrometry. In the end, the purity of niobium after multiple electron beam meltings was found to be 4N while the purity enhanced from 99.9 % (3N) to 99.993 % (4N3), including gaseous impurities, and 99.98 % (3N8) to 99.998 % (4N8) without gaseous impurities. The glow discharge mass spectrometry analytical results of purified niobium indicated that the material is suitable as input material for further processing of fabricated superconducting radio-frequency cavities. In this work, purification of commercial grade (~99.9 %) niobium by multiple Electron Beam Melting (EBM) is reported. Impurity removal of carbon, oxygen, nitrogen, aluminum, iron, molybdenum, zirconium and tungsten in niobium matrix is presented as a part of the ingot melting stages. The minor material loss of niobium during melting is attributed to the amount of decarburization based on the ratio of initial and critical content of oxygen to carbon. The analysis of nearly 60 impurity elements in niobium was carried out by glow discharge mass spectrometry. In the end, the purity of niobium after multiple electron beam meltings was found to be 4N while the purity enhanced from 99.9 % (3N) to 99.993 % (4N3), including gaseous impurities, and 99.98 % (3N8) to 99.998 % (4N8) without gaseous impurities. The glow discharge mass spectrometry analytical results of purified niobium indicated that the material is suitable as input material for further processing of fabricated superconducting radio-frequency cavities.
Lalev, G. M.,Lim, J.-W.,Munirathnam, N. R.,Choi, G.-S.,Uchikoshi, M.,Mimura, K.,Isshiki, M. The Japan Institute of Metals 2009 MATERIALS TRANSACTIONS Vol.50 No.3
<P>Removal of non-metallic impurities like O, N, C and S in 4N Cu rods by argon plasma-arc zone melting and hydrogen plasma-arc zone melting was investigated. The experimental results were discussed on the basis of thermodynamic estimation. Substantial removal of these impurities along the length of the Cu rods by argon plasma-arc zone melting was observed and relatively better removal by hydrogen plasma-arc zone melting was found to be due to activated hydrogen atoms. The removal of O, N, C and S was ascribed to the segregation effect as well as evaporation in the form of CH<SUB>4</SUB>, H<SUB>2</SUB>O and H<SUB>2</SUB>S. As a result, it was found that hydrogen plasma-arc zone melting is a better technique to eliminate non-metallic impurities like O, N, C and S in Cu.</P>
Impurity Behavior in Cu Refined by Ar Plasma-Arc Zone Melting
G. M. Lalev,임재원,N. R. Munirathnam,G.-S. Choi,M. Uchikoshi,K. Mimura,M. Isshiki 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.5
Purification of a 4N grade Cu rod by argon plasma-arc zone melting (APZM) was carried out. Detailed impurity analysis of the Cu rod was performed using glow discharge mass spectrometry (GDMS). Three impurity behavior groups based on segregation and evaporation during APZM were discussed using the GDMS analysis. Although the impurities with segregation coefficient ko < 1 were theoretically expected to be segregated towards the end of the Cu rod, it was found that the segregation effect by APZM can occur when the equilibrium distribution coefficient (ko) is less than 0.4 due to the strong affinity of Cu for some metallic and non-metallic impurities. On the other hand, the impurities for which ko > 1 had no significant reduction in their impurity concentrations. Some impurities, like Mg, S, Cd and Zn, were reduced much faster than the others in Cu. This was ascribed to the removal by zone refining coupled with the evaporation of impurities for Pimp/PCu > 102. Purification of a 4N grade Cu rod by argon plasma-arc zone melting (APZM) was carried out. Detailed impurity analysis of the Cu rod was performed using glow discharge mass spectrometry (GDMS). Three impurity behavior groups based on segregation and evaporation during APZM were discussed using the GDMS analysis. Although the impurities with segregation coefficient ko < 1 were theoretically expected to be segregated towards the end of the Cu rod, it was found that the segregation effect by APZM can occur when the equilibrium distribution coefficient (ko) is less than 0.4 due to the strong affinity of Cu for some metallic and non-metallic impurities. On the other hand, the impurities for which ko > 1 had no significant reduction in their impurity concentrations. Some impurities, like Mg, S, Cd and Zn, were reduced much faster than the others in Cu. This was ascribed to the removal by zone refining coupled with the evaporation of impurities for Pimp/PCu > 102.
Sathish K.V.,Sridhar K.N.,Seenappa L.,Manjunatha H.C.,Vidya Y.S.,Chinnappa Reddy B.,Manjunatha S.,Santhosh A.N.,Munirathnam R.,Raj Alfred Cecil,Damodara Gupta P.S.,Sankarshan B.M. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.5
For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (6000 C) to study the electromagnetic (EM) (X/g) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl2O4, cubic BaðNO3Þ2, a and g phase of Al2O3 which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc’s relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/g) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/g) radiation shielding
Effect of Ar/Ar-H<sub>2</sub> Plasma Arc Melting on Cu Purification
Lim, Jae-Won,Kim, Min-Seuk,Munirathnam, N. R.,Le, Minh-Tung,Uchikoshi, Masahito,Mimura, Kouji,Isshiki, Minoru,Kwon, Hyuk-Chon,Choi, Good-Sun The Japan Institute of Metals 2008 Materials transactions Vol.49 No.8
<P>Removal of impurities from Cu metal by Ar and Ar-20%H<SUB>2</SUB> plasma arc melting (PAM) has been carried out. Several impurities such as Li, Na, Mg, P, S, Cl, K, Ca, Zn, Pd, Pb and Bi in Cu were efficiently removed when only Ar plasma gas was used. Moreover, removal degrees for the above mentioned impurities were significantly increased after Ar-20%H<SUB>2</SUB>-PAM, especially for K, Zn and Pd. It was found that Ar-H<SUB>2</SUB> PAM showed an excellent effect to eliminate impurities with higher vapor pressures than that of Cu metal.</P>
Green synthesis of Lead–Nickel–Copper nanocomposite for radiation shielding
Chandrika B.M.,Manjunatha Holaly Chandrashekara Shastry,Munirathnam R.,Sridhar K.N.,Seenappa L.,Manjunatha S.,Lourduraj A.J. Clement 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.12
For the first time Pb, Ni, and Cu nanocomposites were synthesized by versatile solution combustion synthesis using extract as a reducing agent, to study the potential applications in X-ray/gamma, neutron, and Bremsstrahlung shielding. The synthesized Lead–Nickel–Copper (LNC) nanocomposites were characterized by PXRD, SEM, UV–VIS, and FTIR for the confirmation of successful synthesis. PXRD analysis confirmed the formation of multiphase LNC NCs and the Scherrer equation and the W-H plot gave the average crystal sizes of 19 nm and 17 nm. Surface morphology using SEM and EDX confirmed the presence of LNC NCs. Strong absorption peaks were analyzed by UV visible spectroscopy and the direct energy gap is found to be 3.083 eV. Functional groups present in the LNC NCs were analyzed by FTIR spectroscopy. X-ray/gamma radiation shielding properties were measured using NaI(Tl) detector coupled with MCA. It is found to be very close to Pb. Neutron shielding parameters were compared with traditional shielding materials and found LNC NCs are better than lead and concrete. Secondary radiation shielding known as Bremsstrahlung shielding characteristics also studied and found that LNC NCs are best in secondary radiation shielding. Hence LNC NCs find shielding applications in ionizing radiation such as X-ray/gamma and neutron radiation
Chandrika B.M.,Manjunatha Holaly Chandrashekara Shastry,Sridhar K.N.,Ambika M.R.,Seenappa L.,Manjunatha S.,Munirathnam R.,Lourduraj A.J. Clement 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.5
Barium Bismuth Oxide Borate (BBOB) has been synthesized for the first time using solution combustion technique. SEM analysis reveal flower shape of the nanoparticles. The formation of the nanoparticles has been confirmed through XRD & FTIR studies which gives the physical and chemical structure of the novel material. The UV light absorption is observed in the range 200e300 nm. The present study highlights the radiation shielding ability of BBOB for different radiations like X/Gamma rays, Bremsstrauhlung and neutrons. The gamma shielding efficiency is comparable to that of lead in lower energy range and lesser than lead in the higher energy range. The bremsstrauhlung exposure constant is comparably larger for BBOB NPs than that of concrete and steel however it is lesser than that of lead. The beauty of BBOB nanoparticles lies in, high absorption of radiations and low emission of secondary radiations when compared to lead. In addition, the neutron shielding parameters like scattering length, absorption and scattering cross sections of BBOB are found to be much better than lead, steel and concrete. Thus, BBOB nanoparticles are highly efficient in absorbing X/Gamma rays, neutrons and bremsstrauhlung radiations