• Title, Summary, Keyword: Very-low-boron

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The Effect of Microstructure and Mechanical Property with Heat Treatment Condition in Boron-Treated Low Carbon Low Alloy Steel (저탄소.저합금 보론 첨가강의 열처리 조건에 따른 미세조직과 기계적 성질의 영향)

  • Son, J.Y.;Park, B.C.;Sung, H.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.146-149
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    • 2007
  • The effects of boron additions in steels have long been recognized as very important, mainly with respect to hardnability of heat treatable steels. The systematics of structure and properties of boron steels will then be illustrated in the context of low-alloy steels with carbon contents raging from 0.05 to 0.25% and boron contents 0-130 ppm. we investigated the effect of the microstructure and mechanical properties with heat treatment condition of the boron-treated(0.0013 ppm) low carbon(0.2 %C) low alloy steel. The specimens were austenitised for 5 and 10, 15 min at $880{\sim}940^{\circ}C$(with/without tempered at 150, 180 and $210^{\circ}C$ for the various periods of time from 60 min to 120 min) After heat treatment, mechanical properties were measured by tensile test and hardness test. For analysis of microstructure, Optical/SEM analysis and XRD were carried out.

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The Effect of Microstructure and Mechanical Property with Cooling Rapid in Boron-Treated Low Carbon Low Alloy Steel (저탄소.저합금 보론 첨가강의 냉각속도에 따른 미세조직과 기계적 성질의 영향)

  • Son, J.Y.;Lee, G.D.;Kim, S.G.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.207-210
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    • 2008
  • The effects of boron additions in steels have long been recognized as very important, mainly with respect to hardnability of heat treatable steels. we investigated the effect of the microstructure and mechanical properties with cooling condition after heat treatment of the boron-treated(${\fallingdotseq}8{\sim}18ppm$) low carbon(${\fallingdotseq}0.2%C$) low alloy steel. The specimens were austenitised for 10 min at $910^{\circ}C$, cooled for the various periods of time from 10 sec to 30 sec or with water after forming for 15 sec. After cooling, mechanical properties were measured by tensile test and hardness test. For analysis of microstructure, Optical were carried out.

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Low-Cycle Fatigue in Quenched Boron Steel Sheet Due to Hot Stamping (열간 성형된 보론강판의 저주기 피로 특성)

  • Jang, Won-Seok;Suh, Chang-Hee;Oh, Sang-Kyun;Kim, Dong-Bae;Sung, Jee-Hyun;Jung, Yun-Chul;Kim, Young-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.10
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    • pp.1419-1425
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    • 2010
  • Boron steel sheet is suitable for fabricating automobile parts because it is very strong and has low weight. Recently, many car makers are investigating the feasibility of fabricating the chassis part of automobiles using boron steel. In order to use boron steel sheets to fabricate the chassis part of automobiles, much better material property of low cycle fatigue life as well as high formability during hot stamping is required. Therefore, the low-cycle fatigue life of hot-stamped quenched boron steel was investigated in this study. The fatigue life observed at low strain amplitude was longer than that of an as-received boron steel sheet. However, the fatigue life reduced at high strain amplitude because of the low ductility and low fracture toughness of martensite, which was produced as a result of hot stamping.

Weldability of boron containing low carbon quenched and tempered 60kg/mm$^{2}$ steel with low cold cracking susceptibility (저탄소 B 첨가 60kg/mm$^{2}$급 저균열감수성 조질고강력강의 용접성)

  • 장웅성;김태웅;장래웅;엄기원
    • Journal of Welding and Joining
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    • v.7 no.1
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    • pp.59-66
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    • 1989
  • The weldability and joint performance were evaluated for newly developed 60kg/mm$\^$2/ steel which had low cold cracking susceptibility. The main results obtained were as follows; In case of quenched and tempered 60kg/mm$\^$2/ steels, it was very effective to improve weldability and joint performance by lowering carbon and Pcm level. Very small addition of about 0.001 to 0.002wt% boron exhibited an appreciable compensation effect on strength which was decreased by lowering carbon and Pcm level. As a result, the newly developed steel was able to be welded without preheating and exhibited superior joint performance to conventional steels.

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Optimized Decomposition of Ammonia Borane for Controlled Synthesis of Hexagonal Boron Nitride Using Chemical Vapor Deposition

  • Han, Jaehyu;Kwon, Heemin;Yeo, Jong-Souk
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.285-285
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    • 2013
  • Recently, hexagonal boron nitride (h-BN), which is III-V compound of boron and nitride by strong covalent sp2 bonds has gained great interests as a 2 dimensional insulating material since it has honeycomb structure with like graphene with very small lattice mismatch (1.7%). Unlike graphene that is semi-metallic, h-BN has large band gap up to 6 eV while providing outstanding properties such as high thermal conductivity, mechanical strength, and good chemical stability. Because of these excellent properties, hBN can potentially be used for variety of applications such as dielectric layer, deep UV optoelectronic device, and protective transparent substrate. Low pressure and atmospheric pressure chemical vapor deposition (LPCVD and APCVD) methods have been investigated to synthesize h-BN by using ammonia borane as a precursor. Ammonia borane decomposes to polyiminoborane (BHNH), hydrogen, and borazine. The produced borazine gas is a key material that is a used for the synthesis of h-BN, therefore controlling the condition of decomposed products from ammonia borane is very important. In this paper, we optimize the decomposition of ammonia borane by investigating temperature, amount of precursor, and other parameters to fabricate high quality monolayer h-BN. Synthesized h-BN is characterized by Raman spectroscopy and its absorbance is measured with UV spectrophotometer. Topological variations of the samples are analyzed by atomic force microscopy. Scanning electron microscopy and Scanning transmission Electron microscopy are used for imaging and analysis of structures and surface morphologies.

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Characterization of Tribolayers and Sliding wear at High Temperature between AlCrN Coated Tool Steels and Ultra-high Strength Boron Steels

  • Choi, Byung-Young;Gu, Yoon-Sik
    • Journal of the Korean Society for Heat Treatment
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    • v.24 no.1
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    • pp.37-44
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    • 2011
  • High temperature wear of AlCrN coated tool steels sliding against the ultra-high strength boron steels used for hot press forming has been studied. The sliding wear tests have been carried out using a pin-on-disc of configuration under applied normal load of 50 N for 20 min with heating the ultra-high strength boron steels up to $800^{\circ}C$. Characterizations of tribolayers formed on the contacting surfaces between the tribopairs of the AlCrN coated tool steels and the ultra-high strength boron steels have been studied. It was found on the tribolayers of the AlCrN coated tool steels that microcracking and oxides containing Fe and Cr to increase friction coefficient were formed at the early stage of sliding wear, followed by the generation of the smeared oxide layers containing Fe transferred from the tribopair to decrease friction coefficient. This may mainly contribute to very low specific wear rate of the AlCrN coated tool steels sliding against the ultra-high strength boron steels, resulting from oxideoxide contact between the tribopair.

Effect of Spraying Distance on Properties of $B_4C$ Coating

  • Zeng-Y;Zhang-Y.F;Huang-J.Q
    • Journal of the Korean Vacuum Society
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    • v.7 no.s1
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    • pp.179-182
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    • 1998
  • Boron carbide coating has some very attractive properties for nuclear and semiconductor industry. The potential of atmosheric plasma spray as manufacturing methods for $B_4C$ coating was discussed. In this work, the boron carbide coating with low porosity, high microhardness and good life of thermal shock resistance was deposited by the control of spraying distance. The relationship between the properties of $B_4C$ coatings and their spraying distance was studied.

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Physics study for high-performance and very-low-boron APR1400 core with 24-month cycle length

  • Do, Manseok;Nguyen, Xuan Ha;Jang, Seongdong;Kim, Yonghee
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.869-877
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    • 2020
  • A 24-month Advanced Power Reactor 1400 (APR1400) core with a very-low-boron (VLB) concentration has been investigated for an inherently safe and high-performance PWR in this work. To develop a high-performance APR1400 which is able to do the passive frequency control operation, VLB feature is essential. In this paper, the centrally-shielded burnable absorber (CSBA) is utilized for an efficient VLB operation in the 24-month cycle APR1400 core. This innovative design of the VLB APR1400 core includes the optimization of burnable absorber and loading pattern as well as axial cutback for a 24-month cycle operation. In addition to CSBA, an Er-doped guide thimble is also introduced for partial management of the excess reactivity and local peaking factor. To improve the neutron economy of the core, two alternative radial reflectors are adopted in this study, which are SS-304 and ZrO2. The core reactivity and power distributions for a 2-batch equilibrium cycle are analyzed and compared for each reflector design. Numerical results show that a VLB core can be successfully designed with 24-month cycle and the cycle length is improved significantly with the alternative reflectors. The neutronic analyses are performed using the Monte Carlo Serpent code and 3-D diffusion code COREDAX-2 with the ENDF/B-VII.1.

Ultra low sheet resistance on poly silicon film by Excimer laser activation

  • Lim, Hyuck;Yin, Huaxiang;Xianyu, Wenxu;Kwon, Jang-Yeon;Zhang, Xiaoxin;Cho, Hans-S;Kim, Jong-Man;Park, Kyung-Bae;Kim, Do-Young;Jung, Ji-Sim;Noguchi, Takashi
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1112-1115
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    • 2005
  • In this study, we performed excimer laser activation on Phosphorus or Boron doped a-Si (amorphous silicon) film. We've got a very low sheet resistance (Rs), Rs was 60 ohm/sq. with phosphorus doping and was 65 ohm/sq. with boron doping at each optimized laser irradiation condition. We've found Rs on activated thin film showed an unprecedented behavior in both cases, because Rs had a strong dependency on the crystallinity of the activated Si film.

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Epitaxial Growth of Boron-doped Si Film using a Thin Large-grained Si Seed Layer for Thin-film Si Solar Cells

  • Kang, Seung Mo;Ahn, Kyung Min;Moon, Sun Hong;Ahn, Byung Tae
    • Current Photovoltaic Research
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    • v.2 no.1
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    • pp.1-7
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    • 2014
  • We developed a method of growing thin Si film at $600^{\circ}C$ by hot wire CVD using a very thin large-grained poly-Si seed layer for thin-film Si solar cells. The seed layer was prepared by crystallizing an amorphous Si film by vapor-induced crystallization using $AlCl_3$ vapor. The average grain size of the p-type epitaxial Si layer was about $20{\mu}m$ and crystallographic defects in the epitaxial layer were mainly low-angle grain boundaries and coincident-site lattice boundaries, which are special boundaries with less electrical activity. Moreover, with a decreasing in-situ boron doping time, the mis-orientation angle between grain boundaries and in-grain defects in epitaxial Si decreased. Due to fewer defects, the epitaxial Si film was high quality evidenced from Raman and TEM analysis. The highest mobility of $360cm^2/V{\cdot}s$ was achieved by decreasing the in-situ boron doping time. The performance of our preliminary thin-film solar cells with a single-side HIT structure and $CoSi_2$ back contact was poor. However, the result showed that the epitaxial Si film has considerable potential for improved performance with a reduced boron doping concentration.