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방전플라즈마 소결법에 의해 제조된 다공질 타이타늄 임플란트의 평가
오익현 ( Ik Hyun Oh ),손현택 ( Hyeon Taek Son ),장세훈 ( Se Hun Chang ),김형모 ( Hyung Mo Kim ),이기용 ( Ki Yong Lee ),박순섭 ( Sun Sub Park ),송호연 ( Ho Yeon Song ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.6
Porous Ti compacts were fabricated by spark plasma sintering (SPS) method and their Young`s modulus and biocompatibility were investigated in this study. Ti powders were made from commercially available pure Ti electrode (grade 2) using the plasma rotating electrode process (PREP) in an Ar atmosphere. Porous Ti compacts for biomedical applications were successfully fabricated in the porosity range from 5 to 36 vol%. Young`s modulus of porous Ti compacts having porosity from 31 to 36 vol % is almost the same as that of human cortical bone. To investigate the biocompatibility of pure Ti, fibroblast-like L-929 and osteoblast-like MG-63 cells were cultured with the presence of the extract solution from pure Ti powder and porous body. The viabilities of cells cultured with the diluted extract solutions were almost the same compared to that of the control. Also, porous Ti compacts did not induce any morphologic damage of cell.
방전플라즈마 소결법에 의해 제조된 Al 타겟과 스퍼터링 박막의 특성평가
현혜영 ( Hye Young Hyun ),김민정 ( Min Jung Kim ),유정호 ( Jung Ho Yoo ),정칠성 ( Chil Seong Jeong ),양준모 ( Jun Mo Yang ),오익현 ( Ik Hyun Oh ),박현국 ( Hyun Kuk Park ),이승민 ( Seung Min Lee ),오용준 ( Yong Jun Oh ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.6
The basic properties and electrical characteristics of sputtering films deposited with a commercial cast target and spark plasma sintering (SPS) were compared and analyzed. The results, revealed that, the Al film prepared by heating at 60℃/min (SPS process) showed a specific resistance similar to the commercial cast Al film. In addition, the results of XRD, SIMS and TEM, showed that there was not much difference in the crystal structure and impurities between the two films. Consequently, the SPS Al target was found to have properties quite similar to the commercial one and it is expected to be applied in future research to the metal wiring material for semiconductor/display devices.
마이크로전극에 의한 니켈수소전지용 수산화니켈 입자의 전기화학적 거동
김호성,오익현,이종호,Kim, Ho-Sung,Oh, Ik-Hyun,Lee, Jong-Ho 한국전기화학회 2007 한국전기화학회지 Vol.10 No.2
본 논문은 마이크로전극 측정시스템을 사용하여 니켈수소전지의 전극 소재로 사용되고 있는 수산화니켈의 단일 입자에 대해 전기화학적 평가를 수행 하였다. 즉 Carbon fiber 마이크로전극을 수산화니켈 입자 한개 위에 전기적인 접촉을 이루도록 조정하고 전기화학적 평가를 수행하였다. Cyclic Voltammetry 실험 결과 수산화니켈의 산화 환원 반응과 산소 발생 반응(OER)이 명확하게 분리 되고 있음을 확인하였으며, 전위주사속도를 증가 시킬 경우 환원 전하량은 주사 속도에 의존하지 않고 거의 일정한 수치를 보여 주고 있으나, 산화 전하량은 환원 전하량 보다 크고 주사속도 구간에서 부반응인 산소발생이 증가하고 있음을 확인했다. 그리고 Calvanostat에 의한 정전류 충방전 실험의 결과 수산화니켈 단일 입자의 방전용량은 이론용량 289 mAh/g에 근접한 수치(약 250 mAh/g)를 보여 주었으며 또한 Potential Step에 의해 단일 입자내의 수소이온 확산계수($D_{app}=3{\sim}4{\times}10^{-9}\;cm^2/s$)가 얻어졌다. Electrochemical studies were performed for a single particle of nickel hydroxide for the cathode of Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and electrochemical experiments were performed. As a result of cyclic voltammetry, the oxidation/reduction and oxygen evolution reaction (OER) are clearly separated for a single particle. The total cathodic charge (Qred) is practically constant for the scan rate investigated, indicating that the whole particle has reacted. The total anodic charge(Qox) was larger than that of reduction reaction, and the magnitude of oxygen evolution taking place as a side reaction was enhanced at lower scan rates. As a result of galvanostatic charge and discharge measurement, the discharge capacity of single particle was found to be 250 mAh/g, value being very close to the theoretical capacity (289 mAh/g). The apparent proton diffusion coefficient(Dapp) using potential step method inside the nickel hydroxide was found to range within $3{\sim}4{\times}10^{-9}\;cm^2/s$.
방전플라즈마 소결 공정을 이용한 WC-6wt.%Co 소결체 제조 및 기계적 특성 평가
박국현 ( Hyun Kuk Park ),이승민 ( Seung Min Lee ),윤희준 ( Hee Jun Youn ),방기상 ( Ki Sang Bang ),오익현 ( Ik Hyun Oh ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.1
Using the spark plasma sintering process (SPS process), the WC-6wt.%Co hard materials were densified using an ultra fine WC-Co powder. The WC-Co was almost completely dense with a relative density of up to 100% after the simultaneous application of a pressure of 60 MPa and the DC pulse current for 3 min without any significant change in the grain size. The average grain size of WC that was produced through this experiment was about 0.2~0.8 μm. The hardness and fracture toughness were about 1816 kg/mm2 and 15.1 MPa·m1/2, respectively, for 60 MPa at 1200℃.
펄스전류활성소결법을 이용한 스퍼터링 타겟용 Cu-Mn 소결체 제조 및 특성평가
장준호,오익현,임재원,박현국,Jang, Jun-Ho,Oh, Ik-Hyun,Lim, Jae-Won,Park, Hyun-Kuk 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.1
Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are $700^{\circ}C$ and $80^{\circ}C/min$, respectively. The heating directly progresses up to $700^{\circ}C$ with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of $700^{\circ}C$ without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to $700^{\circ}C$.
가스분무법으로 제조된 Al 합금분말의 펄스통전 소결체의 특성평가
박현국 ( Hyun-kuk Park ),장준호 ( Jun-ho Jang ),이정한 ( Jung-han Lee ),오익현 ( Ik-hyun Oh ) 대한금속ㆍ재료학회 2017 대한금속·재료학회지 Vol.55 No.10
In this study, Al alloy targets were fabricated using the powder metallurgy (pulsed current activated sintering, PCAS) process for metal PVD coating target applications. Powders were prepared from Al, Si and Cu ingots for sintering Al alloy compacts using the gas atomizing process. To fabricate the gas atomized Al alloy powders, processing conditions, such as melting temperature, processing time and gas pressure were optimized and controlled during the gas atomizing process. Al alloy compacts with 200 mm diameters and 1/4 inch thickness were fabricated using a 30,000 A pulsed current activated sintering machine. During the Al alloy compact sintering process, sintering conditions such as temperature, pulse ratio, pressure, and heating rate were controlled and optimized. The Al alloy compacts were fabricated under a uniaxial pressure of 60 MPa at a sintering temperature of 400 ℃ without any significant change in grain size. The grain size and relative density of the Al alloy compacts were 7.3 ㎛ and 100%, respectively. The properties of thin films deposited on a Si substrate using the PCASed target materials were compared with those from a commercial target material prepared using the casting melting process. The thicknesses of the thin films deposited on the Si substrate using the PCASed target material and a commercial target material were about 494 nm and 450 nm, respectively. The specific resistance and surface roughness of the PCASed thin film and commercial thin film were 4.012 × 10<sup>-6</sup> and 4.012 × 10<sup>-6</sup>, 6.105 nm and 6.928 nm, respectively. (Received June 16, 2017; Accepted July 4, 2017)
김주훈,오익현,이정한,홍성길,박현국,Kim, Ju-Hun,Oh, Ik-Hyun,Lee, Jeong-Han,Hong, Sung-Kil,Park, Hyun-Kuk 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.2
Tungsten carbide (WC) hard materials are used in various industries and possess a superior hardness compared to other hard materials. They have particularly high melting points, high strength, and abrasion resistance. Accordingly, tungsten carbide hard materials are used for wear-resistant tools, cutting tools, machining tools, and other tooling materials. In this study, the WC-5wt.%Co, Fe, Ni hard materials are densified using the horizontal ball milled WC-Co, WC-Fe, and WC-Ni powders by a spark plasma sintering process. The WC-5Co, WC-5Fe, and WC-5Ni hard materials are almost completely densified with a relative density of up to 99.6% after simultaneous application of a pressure of 60 MPa and an electric current for about 15 min without any significant change in the grain size. The average grain size of WC-5Co, WC-5Fe, and WC-5Ni that was produced through SPS was about 0.421, 0.779, and $0.429{\mu}m$, respectively. The hardness and fracture toughness of the dense WC-5Co, WC-5Fe, WC-5Ni hard materials were also investigated.