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이도재,이광민,이경구,유창남,오태욱,김수학,윤택림,Lee, Doh-Jae,Lee, Kwang-Min,Lee, Kyung-Ku,Ryu, Chang-Nam,Oh, Tae-Wook,Kim, Soo-Hag,Yoon, Tack-Lim 한국재료학회 2003 한국재료학회지 Vol.13 No.11
The corrosion resistance and cytotoxicity behavior of Ti alloys were studied as a function of Nb contents(3wt.%Nb, 20wt.%Nb, 40wt.%Nb). Ti-Nb alloys were melted by vacuum arc furnace and then rolled to 50% reduction ratio after homogenized at 105$0^{\circ}C$ for 24hrs. The corrosion resistance of Ti-Nb alloys were investigated by potentiodynamic polarization test in the 0.9% NaCl and 5% HCI solution. Biocompatibility of Ti-Nb alloys was evaluated by cytotoxicity test. The results can be summarized as follows 1) The microstructure change from equiaxial to acicular and the increased $\beta$ phase in Ti-Nb alloys were obtained as the Nb content increased. 2) For the corrosion test in the solution of 0.9% NaCl and 5% HCI, the corrosion behavior of Ti-Nb alloys was similar to ASTM grade 2 CP Ti. 3) For the cytotoxicity test, Ti-Nb alloys showed excellent biocompatibility compared to ASTM grade 2 CP Ti, 316L STS and Co-Cr alloys.
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.
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.
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(Doh-Jae Lee),이광민(Kwang-Min Lee),이경구(Kyung-Ku Lee),박범수(Bum-Su Park),김수학(Soo-Hak Kim),전충극(Choong-Geug Jun),윤계림(Kye-Lim Yoon) 한국표면공학회 2004 한국표면공학회지 Vol.37 No.1
The oxidation behavior of Ti-Nb alloys was studied in dry atmosphere. After vacuum arc melting and hot rolling treatment, Ti-Nb alloys were oxidized at 450℃~750℃. The oxidation behaviors between matrix and oxide scale were analyzed by SEM, XPS and XRD. Ti-Nb alloys had higher oxidation resistance than pure Ti at 750℃. XPS analysis of oxide film revealed that TiO₂ oxide was formed on the top of surface. The weight gains during the oxidation increase rapidly at temperature above 600℃ which obey the parabolic law.
가공 열처리에 따른 Ti-10Ta-10Nb합금의 미세조직 및 기계적 특성 변화
이도재 ( Doh Jae Lee ),황주영 ( Ju Young Hwang ),이경구 ( Kyung Ku Lee ),윤계림 ( Kye Lim Yoon ),전충극 ( Choong Geug Jun ) 한국열처리공학회 2005 熱處理工學會誌 Vol.18 No.2
N/A Both commercially pure titanium and Ti-6AI-4V alloy have been widely used as biomaterials because of their excellent biocompatibility, corrosion resistance and mechanical properties. However, in recent years, vanadium has been found to cause cytotoxic effects and adverse tissue reactions, while aluminium has been associated with potential neurological disorders. A newly designed α+ß type Ti alloy, Ti-10Ta-10Nb alloy showed superior properties to CP Ti and Ti-6AI-4V alloy in the point of biomaterial, and elucidated the future uses as a biomaterial. Microstructural changes of Ti-10Ta-10Nb alloy after hot-rolling, warm-rolling, solution and aging treatment were investigated. According to TEM results, the microstructures after solution treatment were composed of mostly α phase with a trace of ß phase due to adding ß-phase stabilizer tantalum and niobium. The microstructures after warm-rolling is coarse and elongated a phase and hot rolling resulted in very fine a widmansta¨tten. The highest value of hardness was obtained by aging treatment at 400℃ for 20hr in which microstructure consisted of very fine a phase in β matrix.
Ti-8wt.%Ta-3wt.%Nb합금의 산화특성 및 생체안정성
이도재(Doh-Jae Lee),이경구(Kyung-Ku Lee),박범수(Bum-Su Park),이광민(Kwang-Min Lee),박상원(Sang-Won Park) 한국표면공학회 2006 한국표면공학회지 Vol.39 No.1
The oxidation behavior and Biocompatibility of pure Ti and Ti-8Ta-3Nb alloy were studied in dry air atmosphere. The specimens showed that Ti-8Ta-3Nb alloy had higher oxidation resistance than pure Ti at 650. Cytotoxicity test also revealed that moderate oxidation treatment lower cell toxicity and Ti-8Ta-3Nb alloy showed better results compared with pure Ti. The weight gains during the oxidation increase rapidly at temperature above 600℃.
용해 및 가공조건 변화가 Ti-10Wt.%Ta-10Wt.%Nb 합금의 미세조직에 미치는 영향
이도재(Doh Jae Lee),이광민(Kwang Min Lee),김민기(Min Ki Kim),이경구(Kyung Ku Lee) 한국주조공학회 2002 한국주조공학회지 Vol.22 No.3
N/A A new titanium based alloy, Ti-10Ta-10Nb, has designed to examine the improved mechanical properties and biocompatibility. A specimen of titanium alloy was melted in a consumable vacuum arc furnace and homogenized at 1050℃ for 24 h. The effect of hot rolling on microstructure was estimated after rolling at 400℃ and 800℃ respectively. Surface of melted alloy by consumable vacuum arc melting was consisted of rough surface and it was changed to sound surface by coating of ZrO_2 slurry on copper mold surface. The hardness of Ti-10Ta-10Nb alloy increased with the amount of α+β phase. Ti-10Ta-10Nb alloy showed Widmansta¨ten structure by hot rolling at 800℃ and in the rolling β-region was negligible effects on microstructure refining.
주철의 흑연구상화에 미치는 Misch Metal Hydride 의 첨가효과
김관휴,이도재,최답천,박충년 ( Kwan Hyu Kim,Doh Jae Lee,Dap Chun Choi,Choong Nyeun Park ) 한국주조공학회 1988 한국주조공학회지 Vol.8 No.3
3.9%C-2.0%Si-Fe 조성의 壓粉體를 1350℃, Ar가스 분위기에서 50분간 용해한 용탕에 市販 misch metal과 misch metal hydride인 MmH와 MmH₂를 각각 여러비율로 添加한후 徐冷및 急冷한 시편의 黑鉛形狀의 변화로부터 misch metal hydride의 球狀化能과 黑鉛球狀化 機構 로서의 氣泡說의 타당성을 고찰한 결과 다음과 같은 결론을 얻었다. 1) Misch metal은 0.5% 이상, 그리고 misch metal hydride는 0.25% 이상 첨가한 때 球狀黑鉛과 C V黑鉛이 나타났으며, misch metal hydride를 첨가한 때가 misch metal에 비하여 黑鉛粒數가 더 많았다. 이와같이 misch metal hydride의 첨가량이 misch metal에 비하여 적었음에도 黑鉛粒數가 더 많은 것을 보면 Mm으로부터 방출되는 多數의 水素氣泡가 球狀黑鉛의 정출장소로 되는 것으로 해석되기 때문에 氣泡說이 타당하다고 생각된다. 2) Misch metal 과 misch metal hydride의 添加量이 1.0%로 증가되면 두경우 모두 黑鉛粒數가 감소하였다. 이는 용탕중에 개재된 水素氣泡의 실수율차이에 의한 잔류 수소기포수의 증가율둔화와 添加量의 증가에 따른 잔류 misch metal량의 相對的 증가로 인한 다량의 잔류 misch metal이 응고과정에서 수소를 재흡수 용해하여 흑연입수를 결정하는 용탕중의 有效水素氣泡數를 감소시켰기 때문으로 생각된다. N/A