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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)
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 $700^{\circ}C$.
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.
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.
티타늄 스크랩을 이용한 분말제조 및 소결 성형체의 특성평가
이승민,최정철,박현국,우기도,오익현,Lee, Seung-Min,Choi, Jung-Chul,Park, Hyun-Kuk,Woo, Kee-Do,Oh, Ik-Hyun 한국재료학회 2010 한국재료학회지 Vol.20 No.3
In this study, Ti powders were fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method. The Ti powders were prepared from the spark plasma sintering (SPS) and their microstructure was investigated. Hydrogenation reactions of Ti scrap occurred at near $450^{\circ}C$ with a sudden increase in the reaction temperature and the decreasing pressure of hydrogen gas during the hydrogenation process in the furnace. The dehydrogenation process was also carried out at $750^{\circ}C$ for 2 hrs in a vacuum of $10^{-4}$ torr. After the HDH process, deoxidation treatment was carried out with the Ca (purity: 99.5%) at $700^{\circ}C$ for 2 hrs in the vacuum system. It was found that the oxidation content of Ti powder that was deoxidized with Ca showed noticeably lower values, compared to the content obtained by the HDH process. In order to fabricate the Ti compacts, Ti powder was sintered under an applied uniaxial punch pressure of 40 MPa in the range of $900-1200^{\circ}C$ for 5 min under a vacuum of $10^{-4}$ torr. The relative density of the compact was 99.5% at $1100^{\circ}C$ and the tensile strength decreased with increasing sintering temperature. After sintering, all of the Ti compacts showed brittle fracture behavior, which occurred in an elastic range with short plastic yielding up to a peak stress. Ti improved the corrosion resistance of the Ti compacts, and the Pd powders were mixed with the HDH Ti powders.
펄스통전활성 소결법 적용 WC 합금 소결체 제조 및 기계적 특성 평가
이정한 ( Jeong-han Lee ),박현국 ( Hyun-kuk Park ),장준호 ( Jun-ho Jang ),홍성길 ( Sung-kil Hong ),오익현 ( Ik-hyun Oh ) 대한금속ㆍ재료학회 2017 대한금속·재료학회지 Vol.55 No.11
In this study, planetary ball milled WC-5 wt%Co powders were sintered using the pulsed current activated sintering (PCAS) process. With this process, fully densified hard materials were obtained in a shorter time than conventional processes such as a HP and HIP. The particle sizes of the planetary ball milled WC and Co were 0.114 μm and 0.154 μm, respectively. The PCAS process was performed at temperatures up to 1300 ℃ with 60 MPa and electric current for 13 min without any significant change in the grain size. The WC-5 wt% Co hard materials were fully densified with a relative density of up to 99.8%. The density of WC-5 wt% Co hard materials increased with increasing shrinkage ratio. In addition, the Co particles penetrated into the WC particles by dissolving and re-precipitation, and finally hard materials were completely densified. The average grain size of the WC-5 wt%Co was 0.25 μm, and the hardness and fracture toughness were 2,386 kg/mm<sup>2</sup> and 6.0 MPa·m<sup>1/2</sup>, respectively. The mechanical properties of the WC-5 wt% Co hard materials were excellent because of grain refinement and densification. (Received June 9, 2017; Accepted July 12, 2017)
루테늄(Ru) 타겟소재 제조를 위한 방전 플라즈마 소결 공정 열해석 시뮬레이션
남효은 ( Hyo Eun Nam ),박현국 ( Hyun Kuk Park ),장준호 ( Jun Ho Jang ),조규종 ( Kyu Zong Cho ),오익현 ( Ik Hyun Oh ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.4
In this study, we have demonstrated that the Marc v.11 simulation program, based on heat transfer, was able to estimate the thermal distribution of a graphite mold and sintered compact, for sintering a Ruthenium (Ru) target material. The thermal distribution simulation analysis was conducted as a function of setting temperatures to obtain basic thermal behaviors, and to determine whether physical properties such as the density, grain size and compactness of the sintered Ru target material were influenced by temperature distribution in the graphite mold. It was found that a very small difference in temperature between the center and edge of the sintered compact could be observed at the simulation temperature of 1200 ℃. The highest relative density of 99.1% was achieved when the Ru target material was sintered at 1200 ℃ by spark plasma sintering(SPS). Also, it was confirmed that the grain size of the sintered Ru target was considerably increased with increasing sintering temperature, in spite of the fast heating rate and short dwell time. From these results, a very meaningful thermal characteristic simulation technique was confirmed that can predict the optimized conditions needed to obtain high quality sintered materials prior to SPS process.
방전플라즈마소결법 적용 승온속도 변화에 따라 제조된 Fe-20Cu-1C 소결체 제조 및 특성평가
유정한,신수식,유병록,김경식,장준호,오익현,김갑태,박현국,Ryu, Jung-Han,Shin, Soo-Sik,Ryu, Byung-Rok,Kim, Kyung-Sik,Jang, Jun-Ho,Oh, Ik-Hyun,Kim, Kap-Tae,Park, Hyun-Kuk 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.4
In this study, Fe-Cu-C alloy is sintered by spark plasma sintering (SPS). The sintering conditions are 60 MPa pressure with heating rates of 30, 60 and $9^{\circ}C/min$ to determine the influence of heating rate on the mechanical and microstructure properties of the sintered alloys. The microstructure and mechanical properties of the sintered Fe-Cu-C alloy is investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The temperature of shrinkage displacement is changed at $450^{\circ}C$ with heating rates 30, 60, and $90^{\circ}C/min$. The temperature of the shrinkage displacement is finished at $650^{\circ}C$ when heating rate $30^{\circ}C/min$, at $700^{\circ}C$ when heating rate $60^{\circ}C/min$ and at $800^{\circ}C$ when heating rate $90^{\circ}C/min$. For the sintered alloy at heating rates of 30, 60, and $90^{\circ}C/min$, the apparent porosity is calculated to be 3.7%, 5.2%, and 7.7%, respectively. The hardness of the sintered alloys is investigated using Rockwell hardness measurements. The objective of this study is to investigate the densification behavior, porosity, and mechanical properties of the sintered Fe-Cu-C alloys depending on the heating rate.
급속소결 방법을 이용한 마찰교반 접합 툴용 WC-Co 소결체 제조 및 특성 평가
박현국,윤희준,유정한,장준호,손인진,오익현,Park, Hyun-Kuk,Youn, Hee-Jun,Ryu, Jung-Han,Jang, Jun-Ho,Shon, In-Jin,Oh, Ik-Hyun 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.6
Using the pulsed current activated sintering method, the WC-10wt.% Co materials were densified using a WC and Co powder. The WC-Co almost completely dense with a relative density of up to 99.5 % after the simultaneous application of a pressure of 60 MPa and an electric current for 3 minutes almost without any significant change in the grain size. The average grain size of about $0.3{\mu}m$. The hardness and fracture toughness at $1000^{\circ}C$ were about $2200kg/mm^2$ and $9.8MPa.m^{1/2}$, respectively.