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정진영,고윤영,이다영,이영석 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1
Spinnable pitch for melt-electrospinning was prepared from pyrolized fuel oil by electron beam (E-beam) radiation. The E-beam treated pitches were characterized by measuring their elemental composition, softening point, viscosity, molecular weight and spinnability. The softening point and molecular weight were increased according to absorbed doses of E-beam radiation and adding AlCl<sub>3</sub>. The range of molecular weight distribution of modified pitch becomes narrow for better spinning owing to generating aromatic compound with similar molecular weight. The diameter of melt-electrospun fibers in applied 20 kV decreased 53% (4.7 ±0.9 μm) compared to that of melt-spun fibers (10.2±2.8 μm).
대면적 전자빔 폴리싱 공정 시 발생하는 온도 분포 유한요소해석 연구
김지수(J. S. Kim),김진석(J. S. Kim),강은구(E. G. Kang),이석우(S. W. Lee),박형욱(H. W. Park) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.6
Recently, the use of large-electron-beam polishing for polishing complex metal surfaces has been proposed. In this study, the temperature induced by a large electron beam was predicted using the heat transfer theory. A finite element (FE) model of a continuous wave (CW) electron beam was constructed assuming Gaussian distribution. The temperature distribution and melting depth of an SUS304 sample were predicted by changing electron-beam polishing process parameters such as energy density and beam velocity. The results obtained using the developed FE model were compared with experimental results for verifying the melting depth prediction capability of the developed FE model.
Jung, Jae-Hyun,Park, Hyung-Ki,Lee, Byoung Soo,Choi, Jaeho,Seo, Bosung,Kim, Hyo Kyu,Kim, Gun Hee,Kim, Hyung Giun Elsevier 2017 Surface & Coatings Technology Vol.324 No.-
<P><B>Abstract</B></P> <P>Titanium parts in special industries such as vacuum, catalyst and medical application require a variety of surface properties with a unique structure for high efficiency. In this study, the unique surface of commercially pure titanium (CP Ti) parts fabricated using Electron Beam Melting (EBM) in the process of additive manufacturing is post-treated by the electrolytic polishing process under conditions ranging from 10 to 30V and 10–600s in order to study the surface characteristics. The possibility of controlling microstructural surface shape according to electrolytic polishing process conditions is presented from the increase of surface area through the formation of micro-dimples on protruding residual powder on the surface to the flattening of entire surface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microstructural study on the surface of additive manufactured pure Ti part after electrolytic polishing. </LI> <LI> It is possible to maximize surface area by forming micro dimpling at the initial stage of electrolytic polishing. </LI> <LI> Identification of surface flattening mechanism of additive manufactured Ti part using electron beam melting. </LI> </UL> </P>
Jung, Jin-Young,Lee, Young-Seak 한국탄소학회 2014 Carbon Letters Vol.15 No.2
Spinnable pitch for melt-electrospinning was obtained from pyrolized fuel oil by electron beam (E-beam) radiation treatment. The modifiedpitch was characterized by measuring its elemental composition, softening point, viscosity, molecular weight, and spinnability. The softening point and viscosity properties of the modifiedpitch were influencedby reforming types (heat or E-beam radiation treatment) and the use of a catalyst. The softening point and molecular weight were increased in proportion to absorbed doses of E-beam radiation and added AlCl3 due to the formation of pitch by free radical polymerization. The range of the molecular weight distribution of the modifiedpitch becomes narrow with better spinning owing to the generated aromatic compounds with similar molecular weight. The diameter of melt-electrospun pitch fibersunder applied power of 20 kV decreased 53% (4.7 ± 0.9 μm) compared to that of melt-spun pitch fibers(10.2 ± 2.8 μm). It is found that E-beam treatment for reforming could be a promising method in terms of time-savings and cost-effectiveness, and the melt-electrospinning method is suitable for the preparation of thinner fibersthan those obtained with the conventional melt-spinning method.
이재혁,진정운,박세준,최달수,유남호,정용식,구본철,여현욱 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.71 No.-
Polyacrylonitrile (PAN) copolymers containing varying amounts of methyl acrylate (MA), P(AN-co-MA),were synthesized as a melt-spinnable precursor of carbonfibers. The rheological properties of P(AN-co-MA) with MA content of 15 mol% at 190 C proved to be suitable for melt-spinning and the PANfiber wasspun from an extruder. In order to prevent remelting and fusion of thefibers in the stabilization process,electron-beam irradiation of over 1500 kGy was used and the melt-spun PANfibers were successfullyconverted to stabilized PANfibers by thermal treatment up to 250 C. Finally, carbonfibers (CFs) wereproduced by pyrolysis of the stabilized PANfibers. The mechanical properties of the resulting-CFs wereevaluated; the tensile strength, tensile modulus, and elongation at break were 1.37 0.2 GPa,110 11.1 GPa, and 1.27 0.28%, respectively. These results suggest the possibility of utilizing meltspinningas a cost-efficient method for fabrication of carbonfibers.
Lee, Jae Hyeok,Jin, Jeong-Un,Park, Sejoon,Choi, Dalsu,You, Nam-Ho,Chung, Yongsik,Ku, Bon-Cheol,Yeo, Hyeonuk Elsevier 2019 Journal of industrial and engineering chemistry Vol.71 No.-
<P><B>Abstract</B></P> <P>Polyacrylonitrile (PAN) copolymers containing varying amounts of methyl acrylate (MA), P(AN-<I>co</I>-MA), were synthesized as a melt-spinnable precursor of carbon fibers. The rheological properties of P(AN-<I>co</I>-MA) with MA content of 15mol% at 190°C proved to be suitable for melt-spinning and the PAN fiber was spun from an extruder. In order to prevent remelting and fusion of the fibers in the stabilization process, electron-beam irradiation of over 1500kGy was used and the melt-spun PAN fibers were successfully converted to stabilized PAN fibers by thermal treatment up to 250°C. Finally, carbon fibers (CFs) were produced by pyrolysis of the stabilized PAN fibers. The mechanical properties of the resulting-CFs were evaluated; the tensile strength, tensile modulus, and elongation at break were 1.37±0.2GPa, 110±11.1GPa, and 1.27±0.28%, respectively. These results suggest the possibility of utilizing melt-spinning as a cost-efficient method for fabrication of carbon fibers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Poly(acrylonitrile-<I>co</I>-methylacrylate) was synthesized as a melt processible carbon fiber precursor. </LI> <LI> Thermal and rheological analysis confirmed flow characteristics suitable for melt-spinning. </LI> <LI> The precursor fibers were thermally stabilized by assistance of electron-beam irradiation without re-melting and fusion. </LI> <LI> The mechanical properties of resulting-carbon fiber were 1.37GPa in tensile strength and 110GPa in modulus, respectively. </LI> </UL> </P>
Preparation of Ultra-High Purity Cylindrical Mo Ingot by Electron Beam Drip Melting
Lee, Back-Kyu,Oh, Jung-Min,Choi, Good-Sun,Rhee, Kang-In,Lee, Seoung-Won,Kim, Sang-Bae,Lim, Jae-Won The Japan Institute of Metals 2012 MATERIALS TRANSACTIONS Vol.53 No.2
<P>A cylindrical Mo ingot with ultra-high purity was obtained by electron beam (EB) drip melting process using a Mo rod. The Mo rod as a bar feeder was prepared from Mo powder by vacuum sintering and swaging processing. Most of impurities excluding W in the Mo ingot were removed down to below ppm level by three-times EB drip melting, where the purity of the Mo ingot except W was improved from the initial Mo powder purity of 3N (99.95%) to 5Nup (99.9998%). Furthermore, the gaseous impurities C, N and O in the Mo ingot were removed to a level below 5 ppm from the initial level of around 460 ppm by repetitive EB drip melting.</P>
Design and 3D-printing of titanium bone implants: brief review of approach and clinical cases
Vladimir V. Popov Jr.,Gary Muller-Kamskii,Aleksey Kovalevsky,Georgy Dzhenzhera,Evgeny Strokin,Anastasia Kolomiets,Jean Ramon 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.4
Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3Dprinting,direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only netshapegeometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables newapplications of the technology in important fields, such as production of medical implants. The 3D-printing of medicalimplants is an extremely rapidly developing application. The success of this development lies in the fact that patientspecificimplants can promote patient recovery, as often it is the only alternative to amputation. The production of AMimplants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerouschallenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technologicaland design chain of bio-medical bone implant production from the computed tomography that is performed by thesurgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processingprocedures and certification. The current work presents examples that were produced by joint work of Polygon MedicalEngineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3Dmodellingspecifically for the implants production. TechMed were in charge of the optimization of models and theymanufactured the implants by Electron-Beam Melting (EBM ), using an Arcam EBM A2X machine.
Melting Depth Characteristics according to Electron Beam Dose for Electron Beam Micro-Hole Drilling
강준구(Joon-Goo Kang),민병권(Byung-Kwon Min),강은구(Eun Goo Kang) Korean Society for Precision Engineering 2021 한국정밀공학회지 Vol.38 No.3
E-Beam micro-hole drilling features high productivity of 2,000 holes per second and a high aspect ratio of 10 (depth/diameter). It can be used for the fabrication of nozzles and filters that require several holes. The hole-formation mechanism comprises 1) melting the sample by the energy exchange of e-beam and 2) removing the molten sample by the explosion of the backing material. Accordingly, hole-formation mechanism studies have focused on the effectiveness of backing material and the workpiece’s melting characteristic. This study investigated the melting depth characteristics depending on the beam current and exposure time that determines the E-Beam dose. The experiments were conducted without using the backing materials with an aim to investigate the melting characteristic of the workpiece itself. The results showed that the increase in the exposure current led to an improvement in the melting depth. The results were verified based on the comparison with the results of the process involving the backing material.