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97Fe-3Cu 계에서 Cu 를 coating 한 Fe 분말의 소결성에 관한 연구
이도재,양현삼 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.1
Various 97Fe-3Cu(wt%) sintered specimens were prepared from mechanically mixed powders and Cu coated powders. Cu-coated Fe powders were prepared by electroless platings (reducing and ion exchange method.) The ion exchange method resulted in better coating of Cu on Fe powder than the reducing plating method. The compacts of Cu-coated Fe powder by ion exchange showed the highest sintered density. The tensile strength and hardness of sintered compacts increased by about 10 and 5D%, respectively, when using Cu-coated Fe powder instead of mechanically mixed Fe-Cu powder. The coating of Cu on Fe powder appears therefore to be useful to improve the sinterability and mechanical properties of Fe-Cu base sintered products.
Fe-Cu 계에서 Cu 가 Coating 된 Fe 분말 압분체의 치수팽창 현상에 관한 연구
이도재,문길원,양현삼,이경구 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.10
The swelling and alloying behaviour of ferrous metal powder compacts have been studied using TMA(thermomechanical analysis) and optical microscope. Binary Fe-Cu compacts containing 3wt% Cu and up to 7wt% Cu were prepared from blends of Fe and Cu powders, and Cu coated Fe powders respectively. The TMA observations indicated that penetration of Cu-liquid phase into Fe particle and grain boundary leads to swelling of the powder compacts during heating and early stage of isothermal sintering at 1150˚C. Those swelling can be suppressed by using Cu coated Fe powder. The alloying process was accompanied by grain boundary penetration of Cu-rich liquid phase.
Hf가 첨가된 생체용 Ti-15Sn-4Nb 합금의 미세조직 및 내식성
이도재,이경구,조규종,윤택림,박효병,Lee, Doh-Jae,Lee, Kyung-Ku,Cho, Kyu-Zong,Yoon, Taek-Rim,Park, Hyo-Byung 대한치과기공학회 2001 대한치과기공학회지 Vol.23 No.1
This study is focusing on the improvement of problems of Ti-6Al-4V alloy. A new Ti based alloy, Ti-15Sn-4Nb, have designed to examine any possibility of improving the mechanical properties and biocompatibility. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at $100^{\circ}C$ for 24h. All specimens were solution treated at $812^{\circ}C$ and aged at $500^{\circ}C$ for 10h. The corrosion resistance of Ti alloys was evaluated by potentiodynamic polarization test and immersion test inl%Lactic acid solutions. Ti-15Sn-4Nb system alloys showed Widmanstatten microstructure after solution treatment which is typical microstructure of ${\alpha}+{\beta}$ type Ti alloys. Analysing the corrosion resistance of Ti alloys, it was concluded that the passive films of Ti-15Sn-4Nb system alloys are more stable than that of Ti-6Al-4V alloys. Also, the corrosion resistance of Ti-15Sn-4Nb system alloys was improved with adding elements, Hf. It was analysed that the passive film of the Ti-15Sn-4Nb alloy which was formed in air atmosphere was consisted of TiO2, SnO and NbO through X-ray photoelectron spectroscopy(XPS) analysis.
Al/SiC 복합재료에서 보강재에 도금된 금속층이 젖음성에 미치는 영향
이도재,이경구,기회봉 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.2
Effects of coating treatment of metallic Cu and Ni-P film on SiC fiber for Al/SiC composite were studied. Ni-P and Cu were deposited on SiC fiber by electroless plating method. The morphology of coated film and wetting behavior of composite were analysed by SEM The coating treatment on SiC fibers improved wettability of Al melt on SiC comparing to the non wated SiC fiber, and especially Ni-P coating turned out most effective. This improved wettability seems strongly concerned to the increase of chemical reactivity between coating layer and Al matrix. The reaction between Al melt and coated metallic film forms eutetic melt, and those reaction may accelerates the break down of Al oxide film to promote wettability positively.
생체용 Ti합금의 산화거동에 미치는 Ta 및 Nb 첨가의 영향
이도재,오태욱,박범수,김수학,전충극,윤계림,Lee Doh-Jae,Oh Tae-Wook,Park Bum-Su,Kim Soo-Hak,Jun Choong-Geug,Yoon Kye-Lim 한국재료학회 2004 한국재료학회지 Vol.14 No.3
The oxidation behaviors of Ti-10Ta-10Nb alloy and Ti-6Al-4V alloy were studied in dry air atmosphere. Specimens were melted in consumable vacuum arc furnace and homogenized at $1050^{\circ}C$ for 24 h. Hot rolling was performed at $1000^{\circ}C$. Specimens of the alloys were oxidized as the temperature range $400~650^{\circ}C$ for 30 min. The oxidation behavior of the alloys was analysed by optical microscope, SEM/EDX, XRD, XPS and TGA. Immersion test was performed in 1% Lactic acid. In the microscope observation, oxide layer of Ti-10Ta-10Nb alloy was denser and thinner than Ti-6Al-4V's. The weight gains during the oxidation rapidly increased at the temperature above $600^{\circ}C$ in Ti-6Al-4V's alloy and$ 700^{\circ}C$ in Ti-10Ta-10Nb alloy. According to XRD results, oxide layers were composed of mostly $TiO_2$(rutile) phase. It was analysed that the passive film of the Ti alloys consisted of $TiO_2$ through X-ray photoelectron spectroscopy(XPS) analysis.
이도재,문길원,이경구 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.10
Effects of coating treatment of metallic film on SiC particles on wetting behavior of liquid Al on SiC were studied. Experimental variables are included types of coated metallic films such as Ni, Cu, and Ag, and temperatures of heat-treatment under vacuum. Model experiments were performed using coarse SiC particles to observe the wetting phenomenon, and Al-SiC_P composites are prepared by powder metallurgical techniques to test mechanical properties. Analysing the experimental results concerning wetting phenomena of liquid Al on SiC, it was found that coating treatment of metallic film on SiC particles seriously improves the wetting behavior of liquid Al on SiC, especially in case of Ni coating. The tensile strength of Al-SiC_P composites made of coated SiC particles showed also higher value than the specimens made of non-coated SiC particles even though the coating treatment was not perfect.
Sn-Bi 계 Solder 에서 Sn 함량이 습윤성 및 계면반응에 미치는 영향
이도재,이경구,이재진 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.8
Solderability and interfacial reaction between Cu-substrate and Sn-Bi solder were studied. Experimental variables included Sn contents, types of flux and soldering temperature. Some solder joints are subjected to aging treatments for up to 90 days to see interfacial reaction at 100℃. Analysing the experimental result concerning solderability, it was found that the role of Sn contents is increasing spread area on Cu substrate during soldering. A similar effect is observed by increasing soldering temperature and using activated flux(RMA flux) instead of using non-activated flux(R flux). According to the result of EDXS(Energy Dispersive X-ray Spectrometer), it is supposed that the soldered interfacial zone was composed of Cu₃Sn and Cu_6Sn_6. Those intermetallic compound formed in interfacial zone changed entirely to Cu₃Sn after 5days annealing at 100℃.
표면 개질에 따른 Ti-8wt.%Ta-3wt.%Nb 합금의 생체적합성
이도재,이경구,박범수,이광민,박상원,Lee, Doh-Jae,Lee, Kyung-Ku,Park, Bum-Su,Lee, Kwang-Min,Park, Sang-Won 한국재료학회 2006 한국재료학회지 Vol.16 No.5
The alloys were prepared by a non-consumable vacuum arc melting and homogenized at $1050^{\circ}C$ for 24 hrs. Two kind of surface modifications were performed alkali treatment in 5.0M NaOH solution subsequent and heat treatment in vacuum furnace at $600^{\circ}C$, and were oxidizing treatment at the temperature range of 550 to $750^{\circ}C$ for 30 minutes. After surface modification, these samples were soaked in SBF which consists of nearly the same ion concentration as human blood plasma. Cytotoxicity tests were performed in MTT assay treated L929 fibroblast cell culture, using indirect methods. A porous and thin activated layer was formed on Titanium and Ti-8Ta-3Nb alloy by the alkali treatment. A bone-like hydroxyapatite was nucleated on the activated porous surfaces during the in vitro test. However, Ti-8Ta-3Nb alloys showed better bioactive properties than Titanium. According to XRD results, oxide layers composed of mostly $TiO_2$(rutile) phases. Cytotoxicity test also revealed that moderate oxidation treatment lowers cell toxicity and Ti-8Ta-3Nb alloy showed better results compared with Titanium.