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Ti-Nb계 합금의 미세조직 및 경도변화에 미치는 열처리 조건의 영향
이도재 ( Lee Do Jae ),이경구 ( Lee Gyeong Gu ),이광민 ( Lee Gwang Min ),황주영 ( Hwang Ju Yeong ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.4
N/A Ti-3wt.%Nb(αtype), Ti-20wt.%Nb(α+β,type) and Ti-40wt.%Nb(βtype) alloys were melted by vacuum are remelting. The specimens were homogenized at 1050℃ for 24 hr and were then hot rolled to 50% reduction. Each alloys were solution heat treated at β zone and α+β, zone after homogenization, and then aged. The microstructural and hardness changes in Ti-Nb alloys with Nb contents were investigated by SEM, XRD and hardness tester. The microstructural change from equiaxied to acicular and the increase of β phase in Ti-Nb alloys were obtained when the Nb content increased. The higher hardness value of α+βtype alloy was obtained compared to the other alloys.
Sn-3.5Ag 땝납의 Zn첨가가 기계적 특성에 미치는 영향
이도재 ( Lee Do Jae ),이광민 ( Lee Gwang Min ),이경구 ( Lee Gyeong Gu ),오태욱 ( O Tae Ug ),백대화 ( Baeg Dae Hwa ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.6
N/A Effects of Zn concentration on the mechanical properties of Sn-3.5Ag solder were studied, and compared to those of Sn-40Pb alloy which is widely used currently in electronics industry. Aging treatments were performed at 100 and 150 for up to 120days and then were examined changes of microstructure by optical microscopy, SEM and EDS. Sn-3.5Ag solder was loaded to failure at cross head speed of 0.3 mm. min-1 to measure strength and elongation. Aging treatment changed more or less the tensile properties of the solder itself. In short, Sn-Ag base alloy showed decrease in tensile strength and increase in elongation with prolonged agig time. Sn-3.5Ag alloy showed more sensitive changes in tensile properties than Sn-3.5Ag-1Zn alloy by aging. On the other hand, Sn-40Pb alloy showed decreasing tendances in both tensile strength and elongation by aging.
Sn-Bi-X계 땜납과 Cu 기판과의 계면반응 및 기계적 특성에 관한 연구
서윤종,이경구,이도재,Seo, Yun-Jong,Lee, Gyeong-Gu,Lee, Do-Jae 한국재료학회 1998 한국재료학회지 Vol.8 No.9
Sn-Bi-X(X:2Cu, 2Sb, 5In) 계 땜납과 Cu 기판과의 계면반응 및 기계적성질에 대하여 고찰하였다. Cu판과 땜납의 접합부는 $100^{\circ}C$에서 60일까지 열처리하여 광학현미경, SEM, EDS,분석을 통하여 시효처리에 따른 미세조직과 계면반응을 분석하였으며, 인장강도 및 연신율은 제조된 시편을 30일까지 열처리 한 후 0.3mm $\textrm{min}^{-1}$로 인장하여 시험하였다. 미세조직 분석결과 Cu의 첨가로 미세조직이 미세화 됨을 알 수 있으며, 계면에 형성된 화합물은 첨가원소에 따라 다르게 나타났다. 인장시험 결과 열처리 초기에는 땜납쪽에서의 파괴가 발생하였으나 열처리 시간이 증가하면서 계면반응층고 땜납의 계면에서 파괴가 발생하였다. 열처리에 따른 인장강도는 Cu를 첨가한 경우에 가장 높은 값을 나타냈다. Interfacial reaction and mechanical properties between Sn-Bi-X ternary alloys(X : 2Cu. 2Sb 5In) and Cu-substrate were studied. Cu/solder joints were subjected to aging treatments for up to 60days to see interfacial reaction at $100^{\circ}C$ and then were examined changes of microstructure and interfacial compound by optical microscopy, SEM and EDS. Cu/solder joints were aged to 30days and then loaded to failure at cross head speed of 0.3mm $\textrm{min}^{-1}$ to measure strength and elongation. According to the result of EDS, it is supposed that the soldered interfacial zone was composed of $\textrm{Cu}_{3}\textrm{Sn}$ and $\textrm{Cu}_{6}\textrm{Sn}_{5}$. According to the tensile test of Cu/solder joint, joint strength was decreased by aging treatment. Fractographs of Cu/Sn-Bi solder detailed the effect of aging on fracture behavior. When intermetallic was thin, the fracture occurred through the solder. But as the interfacial intermetallic is thickened, the fracture propagated along the intermetallic/solder interface.
보강재에 도금된 Cu층이 Al/SiC복합재료의 젖음성에 미치는 영향
이경구,조규종,이도재,Lee, Gyeong-Gu,Jo, Gyu-Jong,Lee, Do-Jae 한국재료학회 2001 한국재료학회지 Vol.11 No.5
SiC 보강재 표면에 도금된 Cu금속층이 Al/SiC복합재료의 젖음성에 미치는 영향을 검토하였다. 보강재에 대한 금속층의 도금은 무전해도금법을 이용하였으며, Al/SiC 복합재료의 제조는 텅스텐 발열체 진공로의$ 670^{\circ}C$~$900^{\circ}C$에서 제조하여 보강재와 기지간의 접촉부위를 촬영하여 젖음성을 측정하였다 젖음성 측정 결과 보강재에 도금된 Cu층은 젖음성을 향상시켰고, 젖음성의 개선은 보강재에 도금된 금속층과 기지간의 반응에 의해 계면에너지를 변화시킴으로서 나타난 결과이며. 반응을 통한 산화피막의 배제도 영향을 미친 것으로 판단된다 Effects of coating treatment of metallic Cu film on SiC for Al/SiC composite were studied. The Copper was deposited on SiC by electroless plating method. Al/sic composite was fabricated at temperature range of $670^{\circ}C$ to 90$0^{\circ}C$ under vacuum atmosphere. The wetting behavior of Al/SiC composite were analysed by SEM and XRD. The coating treatment on SiC improved wettability of Al melt on SiC considerably comparing to the non coated SiC. This improved wettability seems strongly concerned to the increase of chemical reactivity between coated layer and Al matrix. The improvement of wettability of Al melt on the Cu coated SiC was closely related to in the initial stage of reaction. The metallic film played an important role in reducing the interfacial free energy and breaking down the aluminum oxide film through the reaction with Al melt. The wetting behavior of the as-received SiC with Al melt was not uniform, indicated by the contact angles from less than $97^{\circ}$to more than $97^{\circ}$.
심종보,이경구,이도재,Sim, Jong-Bo,Lee, Gyeong-Gu,Lee, Do-Jae 한국재료학회 1998 한국재료학회지 Vol.8 No.1
Sn-Zn계 solder에서 Zn함량의 변화에 따른 납땜성을 납땜분위기 및 용제를 달리하여 연구하였다. 계면에서의 미세조직 관찰은 열처리온도를 8$0^{\circ}C$와 10$0^{\circ}C$로 달리하여 100일간 열처리한 후 관찰하였다. 젖음성 측정 결과, Zn함량이 증가함에 따라 젖음성은 감소하였고 RMA-용제를 사용한 경우가 R-용제를 사용한 경우에 비해 젖음성이 향상되었다. Sn-9Zn의 접촉각은 약 45도이고, 공기중에서 보다 질소 분위기에서 납땜한 경우가 젖음성 개선을 나타냈다. Sn-9Zn땝납과 Cu기판에서의 계면반응을 XRD, EDS로 분석한 결과 계면화합물은 r상(Cu$_{5}$Zn$_{3}$)으로 구성되어 있음을 알 수 있으며, 시효처리에 따라 접합부의 solder쪽에는 Zn상의 고갈이 나타남을 확인할 수 있었다.
Ion beam assisted DC magnetron sputtering에 의한 렌즈 유리 성형용 WC 합금의 Ir-Re 박막 특성
박종석(Jong-seok Park),박범수(Burm-su Park),강상도(Sang-do Kang),양국현(Kook-hyun Yang),이경구(Kyung-Ku Lee),이도재(Doh-jae Lee),이광민(Kwang-min Lee) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.3
Ir-Re thin films with Ti interlayer were deposited onto the tungsten carbide substrate by ion beam assisted DC magnetron sputtering. The Ir-Re films were prepared with targets of having two atomic percent of 7:3 and 5:5. The microstructure and surface analysis of the specimen were conducted by using SEM, XRD and AFM. Mechanical properties such as hardness and adhesion strength of Ir-Re thin film also were examined. The interlayer of pure titanium was formed with 100 ㎚ thickness. The film growth of Ir-30at.%Re was faster than that of Ir-50at.%Re in the same deposition conditions. Ir-Re thin films consisted of dense and columnar structure irrespective of the different target compositions. The values of hardness and adhesion strength of Ir-30at.%Re thin film coated on WC substrate were higher than those of Ir-50at.%Re thin film.
생체용 Ti-15Sn 계 합금의 내식성 및 기계적 성질에 관한 연구
김대환,이경구,박효병,이도재 한국주조공학회 2000 한국주조공학회지 Vol.20 No.3
The mechanical properties and corrosion resistance of Ti alloys for medical implants have been investigated. Ti, Ti-15Sn-4Nb and Ti-15Sn-4Nb-2Zr alloys were melted in arc furnace and the corrosion resistance of Ti alloys was evaluated by anodic polarization test. The microstructure and mechanical properties of Ti alloys were analysed by optical microscope, hardness and tensile tester. The tensile strength of the pure-Ti improved by addition of Sn and Nb and Ti-15Sn-4Nb alloy showed better Rockwell hardness compared with pure Ti. However, there was no significant difference in corrosion resistance between those Ti-alloys made of Pure-Ti and Ti-15Sn-4N6 alloy. The passive films on the Ti-15Sn-4Nb alloy in air atmosphere consisted of TiO₂, SnO and NbO as demonstrated by X-ray photoelectron spectroscopy(XPS)