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이총민 ( Chong Min Lee ),김지웅 ( Ji Woong Kim ),장한권 ( Han Kwon Chang ),노기민 ( Ki Min Roh ),장희동 ( Hee Dong Jang ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.1
Hollow silica particles were prepared using sodium silicate and organic templates. Polystyrene latex (PSL) particles produced by dispersion polymerization were used as organic templates. PSL particles ranged from 1 um to 3 um in diameter were synthesized by adjusting the amount of 2,2`-azobisisobutyronitrile (AIBN). The PSL/SiO2 core-shell particles were prepared by coating of silica nanoparticles originated from sodium silicate using sol-gel method. The organic templates were removed by the organic solvent, tetrahydrofuran (THF). Morphology of hollow silica particles was investigated with respect to types of the reaction medium and pH during the process. By changing the solvent from ethanol to water, hollow silica particles were successfully formed. Hollow silica particles with the uniform shell thickness were produced at low pH as well. The reflectivity of the as-prepared silica particles was measured in the range of the wavelength of UV and visible light. Hollow silica particles showed much better reflective properties than the commercial light reflector, Insuladd.
Ti-6Al-4V 및 Ti-8Al-1Mo-1V 합금 스크랩을 이용한 저산소 분말 제조와 탈산방법 비교
오정민,서창열,권한중,임재원,노기민,Oh, Jung-Min,Suh, Chang-Youl,Kwon, Hanjung,Lim, Jae-Won,Roh, Ki-Min 한국자원리싸이클링학회 2015 資源 리싸이클링 Vol.24 No.1
Ti-6Al-4V 및 Ti-8Al-1Mo-1V (AMS 4972) 합금 스크랩을 대상으로 수소화-탈수소화(HDH) 기술로 분말을 제조하고 칼슘 접촉식과 비접촉식 방법으로 탈산을 실시하여 탈산효과를 비교하였다. 타이타늄을 대상으로 한 이전 연구결과에서는 비접촉식 탈산법이 탈산 효과가 더 크다고 보고되었으나 산소함유량을 분석한 결과 Ti-6Al-4V 및 Ti-8Al-1Mo-1V 합금 분말 모두 비접촉식으로 탈산한 분말의 산소함유량이 더 높은 것으로 밝혀졌다. 따라서, 본 연구에서는 XRD와 가스분석기를 이용하여 합금 내에 가장 많이 함유되어 있는 알루미늄이 비접촉식 탈산 공정 중 탈산에 미치는 영향을 조사하였다. The present study describes the process of producing low oxygen content alloy powder from Ti-6Al-4V and Ti-8Al-1Mo-1V (AMS 4972) alloy scraps using hydrogenation-dehydrogenation (HDH) and deoxidation in solid state (DOSS) processes. Each prepared powder was deoxidized with Ca contact and non-contact method to compare the deoxidation capability. It is known that the non-contact deoxidation method, using Ca vapor above the melting temperature $T_m$ of Ca, has greater deoxidation capability. However, Oxygen contents in Ti-6Al-4V and Ti-8Al-1Mo-1V powder after non-contact deoxidation method were higher than those after contact deoxidation method. Therefore, we investigate the effect of Al - the richest alloy element in theses Ti based metals - on the deoxidation processes.
펄스전류활성 소결에 의한 나노구조 TiN-AlN 복합재료 제조 및 기계적 특성
김원백 ( Won Baek Kim ),서창열 ( Chang Yul Suh ),노기민 ( Ki Min Roh ),임재원 ( Jae Won Lim ),심현보 ( Hyun Bo Shim ),박현국 ( Hyun Kuk Park ),손인진 ( In Jin Shon ) 대한금속재료학회(구 대한금속학회) 2012 대한금속·재료학회지 Vol.50 No.11
A dense nanostructured TiN-AlN composite was prepared from high-energy ball milled TiN-AlN mixture powders by pulsed current activated sintering (PCAS). A highly dense TiN-AlN bulk composite was obtained within 2 minutes at 1500℃ with the simultaneous application of 80 MPa pressure and pulsed current. The fine crystalline structure of the TiN-AlN mixture, which was obtained by high-energy milling, was effectively maintained during PCAS and resulted in the enhancement of the mechanical properties. The micro hardness and fracture toughness of TiN-AlN composite were 1780 kg/mm2 and 5 MPa.m1/2, respectively. The mechanical properties were higher than monolithic AlN or TiN.
기계적 합성된 분말로부터 펄스전류활성 소결에 의한 나노구조 1.5TiAl-Al2O3 복합재료 제조 및 기계적 특성
김원백 ( Won Baek Kim ),왕희지 ( Hee Ji Wang ),노기민 ( Ki Min Roh ),조성욱 ( Sung Wook Cho ),임재원 ( Jae Won Lim ),손인진 ( In Jin Shon ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.4
Nano-powders of 1.5TiAl and Al2O3 were synthesized from 1.5TiO2 and 3Al powders by high energy ball milling. Nanocrystalline Al2O3 reinforced composite was consolidated by pulsed current activated sintering within 2 minutes from mechanochemically synthesized powders of Al2O3 and 1.5TiAl. The relative density of the composite was 99.5%. The average hardness and fracture toughness values obtained were 1250 kg/mm2 and 10 MPa·m1/2, respectively.