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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.
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.
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.
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℃.
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.
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.
Bi 를 첨가한 Sn-3.5wt.%Ag 땜납의 미세조직 및 기계적 성질
이경구(Kyung Ku Lee),백대화(Dae Hwa Baek),서윤종(Youn Jong Seo),이도재(Doh Jae Lee) 한국주조공학회 2001 한국주조공학회지 Vol.21 No.4
N/A Microstructure and mechanical properties of Sn-3.lwt% Ag-6.9wt% Bi system solders on Cu-substrate were studied. The Sn-3.1wt% Ag-6.9wt% Bi alloy was designed by phase diagram and chemical properties and was prepared by melting in argon atmosphere. The mechanical properties of solder/Cu joints were examined by shear strength test, and also creep test. The microstructure of Sn-3.1wt% Ag-6.9wt% Bi alloy consists of Bi-rich phase and Ag₃Sn precipitate in β-Sn matrix phase. The shear strength of the joint was decreased with aging treatment. Crack path under shear test was through the solder. Similar crack path change mode was observed at the creep test of solder/Cu joint. The creep behavior of Sn-3.1wt% Ag-6.9wt% Bi alloy represented the inverse primary creep behavior at all test condition. It is suggested that the inverse primary creep behavior is induced from Bi solute atoms in Sn-matrix. The creep resistance of Sn-3.1 Ag-6.9Bi alloy is better than that of Sn-3.5wt% Ag alloy at all test conditions.
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.
Squeeze Casting 법에 의해 제조된 A356 / coated SiC 복합재료의 미세조직과 기계적 특성에 관한 연구
이경구,이도재 ( Kyung Ku Lee,Doh Jae Lee ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.5
N/A Influence of interfacial structure between matrix and particle in A356/coated SiC composite fabricated by squeeze casting method was studied. Experimental variables are types of coated metallic film on SiC particles such as Cu, Ni-P, and applied pressure for squeeze casting. It was found that coating treatment on SiC particles improves the wetting of liquid A356 alloy on SiC particles. SiC particle distribution is very homogeneous in A356 matrix alloy which is fabricated by squeeze casting. Analysing the surface morphology of fractured A356/coated SiC, it was concluded that metallic thin film by coating treatment on SiC particle improves the interfacial bonding between particle and matrix, and so does on mechanical properties such as tensile strength. However, there was on significant difference in hardness between those composite made of as-received SiC particle and coated SiC particle.