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PCAS공정에 의한 고융점 소결체 열전달 해석 및 특성분석
남효은 ( Hyo-eun Nam ),장준호 ( Jun-ho Jang ),박현국 ( Hyun-kuk Park ),오익현 ( Ik-hyun Oh ) 한국센서학회 2017 센서학회지 Vol.26 No.3
In this study, the effects of internal heat treatment associated sintering temperatures were simulated by the Finite Element Method (FEM). The sintering mechanism of pulsed current activated sintering process (PCAS) is still unclear because of some unexplainable heat transfer phenomena in coupled multi-physical fields, as well as the difficulty in measuring the interior temperatures of metal powder. We have carried out simulation study to find out thermal distributions between graphite mold and Ruthenium powder prior to PCAS process. For PCAS process, heating rate was maintained at 100 ℃/min the simulation indicates that the sintering temperature range was between 1000 ℃ to 1300 ℃ under 60 MPa. The heat transfer inside the Ruthenium sintered-body sample was modelled through the whole process in order to predict the minimum interior temperature. Thermal simulation shows that the interior temperature gradient decreased by graphite punch length and calculation results well agreed with the PCAS field test results.
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.
스퍼터링 타겟 적용을 위한 방전플라즈마 소결공법으로 소결된 Cu의 특성평가
장준호 ( Jun Ho Jang ),박현국 ( Hyun Kuk Park ),우기도 ( Kee Do Woo ),남효은 ( Hyo Eun Nam ),오익현 ( Ik Hyun Oh ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.1
Pure Cu compacts were fabricated by spark plasma sintering (SPS) process for sputtering target application. For the fabrication of the Cu compacts, conditions such as temperature, pulse ratio, pressure, and heating rate were optimized during the sintering process. The final sintering temperature required to fabricate the target materials with high density, and the heating rate up to the final temperature, were 800 °C and 80 ℃/min, respectively. The heating directly progressed to 800 °C without any holding time. Sputtering target materials with high relative density of 99.7% were fabricated in a uniaxial pressure range of 60 MPa at a sintering temperature of 800 °C, without any significant change in the grain size. Also, the shrinkage displacement of the Cu target materials was found to considerably increase with increasing pressure at sintering temperatures up to 800 °C.