http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Surface Segregation of Sulfur in Ti and Ti - Aluminide Alloys
이원식(W.S. Lee),이재희(J.H. Lee) 한국진공학회(ASCT) 1996 Applied Science and Convergence Technology Vol.5 No.1
Auger electron spectroscopy(AES), ion scattering spectroscopy(ISS), secondary ion mass spectrometry(SIMS) 등을 사용하여 시료의 온도를 20℃에서 1000℃까지 변화시키면서 고순도 Ti 다결정과 Ti-aluminide 합금에서 황의 표면석출 현상을 조사했다. 400℃ 이상에서 Ti 다결정 표면의 산소, 탄소 성분은 사라지고 황 성분은 0.5 단층까지 증가되었다. 400℃ 이하에서는 표면의 산소와 탄소가 황이 표면석출될 자리를 점유함으로써 황의 표면석출 현상에 큰 영향을 주었다. 다결정 Ti에서 황의 표면석출 활성화 에너지는 단결정 Ti에서 황의 표면석출 활성화 에너지보다 아주 적은 16.7kcal/m이었다. 따라서 다결정 Ti에서 황의 표면석출은 결정경계나 결함 확산기구를 따른다고 생각된다. Ti-aluminide 합금에서는 알루미늄이 표면으로 석출되어 높은 온도에서도 산소를 표면에 보유함으로써 황의 표면석출 현상에 영향을 주었다. 알루미늄의 양이 비교적 많은 γ합금인 경우 1000℃ 근방에서도 표면에 많은 양의 산소가 존재했으며 이로 인하여 표면에 석출된 황의 양도 가장 적었다. The segregation of S in electrotransport-purified polycrystalline α-Ti and Ti-aluminide alloys has been studied by Auger electron spectroscopy(AES), Ion scattering spectroscopy(ISS) and Secondary ion mass spectrometry(SIMS) in the temperature range extending from 20 to 1000℃. The chemisorbed oxygen and carbon on Ti were observed to disappear at T>400℃ after which the S signal increased to levels approaching 0.5 monolayer. At lower temperatures the presence of the surface oxygen and carbon appeared to inhibit the segregation, presumably because there were no available surfaces sites for the S emerging from the bulk. The activation energy for the S segregation in pure polycrystalline Ti was determined to be 16.7 kcal/mol, which, when compared to S segregation from single-crystal Ti, is quite small and suggests grain boundary or defect diffusion segregation kinetics. In the Ti-aluminide alloys, the presence of Al appeared to enhance the retention of surface oxygen which, in turn, substantially reduced the S segregation. The γ alloy, with its high Al content, exhibited the greatest retention of surface oxygen and the smallest quantity of the S segregation(T∼1000℃).
진동 하중을 이용한 마이크로 부품 및 표면 패턴 성형 기술
나영상(Y. S. Na),이종훈(J. H. Lee),이원식(W. S. Lee) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
Vibration micro-forming of pyramidal shape patterns was conducted for an Al superplastic alloy. Al 5083 and a Zr-based bulk metallic glass, Zr62Cu17Ni13AI8. A vibrational micro-forming. The micro-formed pattern height was increasing with increasing the frequency of the vibrational load. In particular, the vibrationally-microformed pattern height was similar or even higher than the statically-icroformed pattern height when the load frequency exceeded about 125 kHz. It was also observed that the crystal grains affect the surface quality of the microformed pattern and the distribution of the pattern height in the die cavity array.
이원식(W.S. Lee),고세현(S.H. Ko),장진만(J.M. Jang),김일호(I.H. Kim) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
Manufacturing technology of micro spur gear and micro mold by micro PIM were studied with stainless steel feedstock. For molding of gears, micro mold with gear cavity of 1.2㎜ in diameter was produced by wire EDM. The proper injection pressure was selected to 70bar by observation and measuring of shapes and shrinkage of gears before/after sintering. For fabrication of micro mold, a tiny polymer gear was produced by injection into the mold. Then, 316L feedstock was again injected/compressed on the polymer gear and debinded together with polymer gear followed by sintering. As a result, another metal mold with gear cavity reduced to about 20% was fabricated and through repetition of this process chain, micro gear mold with cavity about below 800 um was finally obtained. In reduction of size by injection/compression molding, height of gear tooth was shrunk more and the effort for decrease of roughness of micro cavity were carried out ultrasonic polishing and as a result, the roughness in cavity decreased from 3-4 um to about 200nm.
실리콘이온주입된 실리콘산화막의 광루미니센스에 관한 연구
김광희(K. H. Kim),이재희(J. H. Lee),김광일(K. I. Kim),고재석(J. S. Koh),최석호(S. H. Choi),권영규(Y. K. Kwon),이원식(W. S. Lee),이용현(Y. H. Lee) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.2
실리콘산화막에 실리콘이온주입을 5×10^(16)/㎠, 1×10^(17)/㎠, 3×10^(17)/㎠ 으로 하여 열처리온도와 열처리시간을 변화시키면서 광루미니센스, XRD, TEM을 관찰하였다. 이온주입량이 적고 열처리온도가 낮을경우에 가시광 광루미니센스를 관찰할 수 있었다. 광루미니센스의 peak는 7420Å과 8360Å 위치에 있었으며, 열처리시간이 길어짐에 따라 intensity는 각각 증가하였다. 이온주입량이 많고 열처리온도가 높을경우에는 광루미니센스가 관찰되지 않았다. 이온주입량이 적고 열처리온도가 높을경우에는 열처리시간이 짧으면 가시광 광루미니센스가 있으나 열처리시간이 1시간 이상으로 길어지면 광루미니센스가 사라졌다. XRD와 TEM 결과로부터 실리콘 cluster는 nonradiative defect와 관련있으며, 실리콘이온주입된 실리콘산화막에서 관찰되는 광루미니센스의 origin은 nanocrystal 이 아니라 defect임을 알 수 있었다. 이온주입되는 실리콘이온의 량, 열처리온도와 시간의 변화는 광루미니센스를 변화시키는데 이 현상들을 Si-O-O 결합인 O위주의 결함과 Si-Si-O 결합인 Si 위주의 결함과 연관지어 설명할 수 있었다. Photoluminescence(PL), XRD, TEM results of 5×10^(16)/㎠, 1×10^(17)/㎠, 3×10^(17)/㎠ Si^+-implanted SiO₂ films on crystalline silicon are reported. At low dose implantation and low annealing temperature, visible PL are observed. The PL spectrum has 7400Å and 8360Å peaks. As annealing time increased, the PL intensity are increased and peak positions are changed. The PL spectrum are not observed at high dose implantation and high annealing temperature. For the samples of low dose and high annealing temperature, visible PL are observed at short annealing time (30 minutes) and disappear for more than 1 hour annealing. From XRD and TEM results, silicon cluster are related to nonradiative defects. It is concluded that the origin of visible PL in Si^+-implanted SiO₂ films are not nanocrystal but two kinds of radiative defects. The Si-O-O bonding related defects (O rich defects) and Si-Si-O bonding related defects (Si rich defects) are related to the PL spectrum and depend on concentration of Si^+ implantation, annealing temperature and time.