• Title/Summary/Keyword: Titanium

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Titanium Dioxide Nanofibers Prepared by Using Electrospinning Method

  • Ding, Bin;Kim, Chul Ki;Kim, Hak Yong;Seo, Min Kang;Park, Soo Jin
    • Fibers and Polymers
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    • v.5 no.2
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    • pp.105-109
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    • 2004
  • The synthesis of titanium dioxide nanofibers with 200-300nm diameter was presented. The new inorganic-organic hybrid nanofibers were prepared by sol-gel processing and electrospinning technique using a viscous solution of titanium isopropoxide (TiP)/poly(vinyl acetate) (PVAc). Pure titanium dioxide nanofibers were obtained by high temperature calcination of the inorganic-organic composite fibers. SEM, FT-IR, and WAXD techniques were employed to characterize these nanofibers. The titanium dioxide nanostructured fibers have rougher surface and smaller diameter compare with PVAc/TiP composite nanofibers. The anatase to rutile phase transformation occurred when the calcination temperature was increased from $600^{\circ}C$ to $1000^{\circ}C$.

Preparation of SiC Composite by the Method of Reaction-Bonded Sintering (반응결합 소결법을 이용한 SiC 복합체 제조)

  • 한인섭;양준환;정윤중
    • Journal of the Korean Ceramic Society
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    • v.31 no.5
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    • pp.561-571
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    • 1994
  • For the preparation of SiC composite, the properties of reaction sintering in the SiC-C-Si-Ti system with the titanium contents variation were investigated. Either the case of titanium additions or the case of direct infiltration of titanium in SiC+C preform, the newly formed fine-grained $\beta$-SiC, which was reacted from the molten silicon with graphite, was intergranulated between the original $\alpha$-SiC particles. Also titanium disilicide (TiSi2) was discontinuously formed isolated pocket in silicon matrix. The amount of titanium disilicide was gradually increased as titanium content increase. With the results of hardness and fracture toughness measurement, SiC-titanium disilicide (TiSi2) composite represented high properties compared with the system of the infiltrated pure silicon.

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Color Evolution in Anodized Titanium (양극산화로 제작된 티타늄의 발색효과 연구)

  • 송오성;홍석배;이정임
    • Journal of the Korean institute of surface engineering
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    • v.35 no.5
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    • pp.273-278
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    • 2002
  • We oxidized pure titanium by anodizing oxidation process in the range of 590V, within 1.5A, 30seconds. we investigated color evolution with a spectrophotometer. Surface images and surface roughness were characterized by an optical microscope and an atomic force microscope, respectively. Below the thickness of 40 $\mu\textrm{m}$, metallic yellow, blue, and pink colorsn were obtained. Lightness decreased, increased, and decreased again as titanium oxide thickness increased. Blue color at the applied voltage of 30V showed the best lightness and reproducibility with surface roughness below l$\mu\textrm{m}$. Bare titanium and titanium oxide films had micro pits more than 10ea/$\mu\textrm{m}^2$. We report that we successfully made colors by varing thickness below 40$\mu\textrm{m}$ with anodizing oxidation of method.

Wetting properties between silver-copper-titanium braze alloy and hexagonal boron nitride

  • Sechi, Yoshihisa;Matsumoto, Taihei;Nakata, Kazuhiro
    • Proceedings of the KWS Conference
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    • pp.205-209
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    • 2009
  • Wetting properties between silver-copper-titanium braze alloys with different titanium contents up to 2.8 mass% and hexagonal boron nitride ceramics were investigated using sessile drop method at 1123K in Argon. The final contact angle is less than $30^{\circ}$ when the Ti content was over 0.41 mass%. Meanwhile, the contact angle curves show different behavior. In case of using braze alloy containing 2.8 mass% of titanium, the initial contact angle is acute angle just after the melting of braze. In case of brazes containing titanium less than 2.26 mass%, the contact angle is larger than $90^{\circ}$ at the beginning and slowly decreases to acute angle. The reaction layer of titanium nitride is observed at the interface. In addition, the reaction of Ti in the braze and N in the bulk h-BN seemed to show diffusion limited spreading.

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A COMPARISON OF FRACTURE STRENGTHS OF PORCELAIN-FUSED-TO-TITANIUM CROWN AMONG TITANIUM SURFACE COATING TREATMENTS (타이타늄 표면 코팅 처리에 따른 타이타늄도재관의 파절강도 비교)

  • Kim, Ji-Hye;Park, Sang-Won;Vang, Mong-Sook;Yang, Hong-So;Park, Ha-Ok;Lim, Hyun-Pil;Oh, Gye-Jeong;Kim, Hyun-Seung;Lee, Kwang-Min;Lee, Kyung-Ku
    • The Journal of Korean Academy of Prosthodontics
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    • v.45 no.2
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    • pp.203-215
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    • 2007
  • Statement of problem: Titanium and its alloy, with their excellent bio-compatibility and above average resistance to corrosion, have been widely used in the field of dentistry. However, the excessive oxidization of titanium which occurs during the process of firing on porcelain makes the bonding of titanium and porcelain more difficult than that of the conventional metal-porcelain bonding. To solve this problem related to titanium-porcelain bonding, several methods which modify the surfaces, coat the surfaces of titanium with various pure metals and ceramics, to enable the porcelain adhesive by limiting the diffusion of oxygen and forming the adhesive oxides surfaces, have been investigated. Purpose: The purpose of this study was to know whether the titanium-porcelain bonding strength could be enhanced by treating the titanium surface with gold and TiN followed by fabrication of clinically applicable porcelain-fused-to-titanium crown Material and method: The porcelain-fused-to-titanium crown was fabricated after sandblasting the surface of the casting titanium coping with $Al_2O_3$ and treating the surface with gold and TiN coating followed by condensation and firing of ultra-low fusing porcelain. To compare with porcelain-fused-to-titanium crowns, porcelain-fused-to-gold crowns were fabricated and used as control groups. The bonding strengths of porcelain-fused-to-gold crowns and porcelain-fused-totitanium crowns were set for comparison when the porcelain was fractured on purpose to get the experimental value of fracture strength. Then, the surface were examined by SEM and each fracturing pattern were compared with each other Result:Those results are as follows. 1. The highest value of fracture strength of porcelain-fused-to-titanium crowns was in the order of group with gold coating, group with TiN coating, group with $Al_2O_3$ sandblasting. No statistically significant difference was found among the three (P>.05). 2. The porcelain-fused-to-gold crowns showed the highest value in bonding strength. The bonding strength of crowns porcelain-fused-to-titanium crowns of rest groups showed bonding strength reaching only 85%-94% of that of PFG, though simple comparision seemed unacceptable due to the difference in materials used. 3. The fracturing patterns between metal and porcelain showed mixed type of failure behavior including cohesive failure and adhesive failure as a similar patterns by examination with the naked eye and SEM. But porcelain-fused-to-gold crowns showed high incidence of adhesive failure and porcelain-fused-to-titanium crowns showed high incidence of cohesive failure. Conclusion: Above results proved that when fabricating porcelain-fused-to-titanium crowns, treating casting titanium surface with gold or TiN was able to enhance the bonding strength between titanium and porcelain. Mean value of masticatory force was found to showed clinically acceptable values in porcelain bonding strength in all three groups. However, more experimental studies and evaluations should be done in order to get better porcelain bonding strength and various surface coating methods that can be applied on titanium surface with ease.

Backward Extrusion Process Analysis and Ductile Fracture Minimization of Titanium (티타늄합금의 후방압출 공정해석 및 연성파괴 최소화)

  • 신태진;이유환;이종수;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.351-354
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    • 2003
  • Titanium alloys are a vital element for developing advanced structural components, especially in aerospace applications. However, process design for successful forming of titanium alloy is a difficult task, which is to be achieved within a very narrow range of process parameters. Presented in this paper is a finite element - based optimal design technique as applied to ductile fracture minimization process design in backward extrusion of titanium alloys.

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Evaluation of Pess Formability for Ti-6Al-4V Sheet at Elevated Temperature (Ti-합금판재(Ti-6Al-4V)의 고온 성형성 평가)

  • Park, J.G.;Park, N.K.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.19 no.4
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    • pp.230-235
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    • 2010
  • Titanium alloy sheets have excellent specific strength and corrosion resistance as well as good performance at high temperature. Recently, titanium alloys are widely employed not only for aerospace parts but also for bio prothesis and motorcycle. However, the database is insufficient in the titanium alloy for press forming process. In this study, the effect of temperature on the forming limit diagram was investigated for Ti-6Al-4V titanium alloy sheet through the Hecker‘s punch stretching test at elevated temperature. Experimental results obtained in this study can provide a database for the development of press forming process at elevated temperature of Ti-6Al-4V titanium alloy sheet. From the experimental studies it can be concluded that the formability of Ti-6Al-4V titanium alloy sheet is governed by the ductile failure for the testing temperature. The formability of Ti-6Al-4V titanium alloy sheet at $700^{\circ}C$ increases about 7 times compared with that at room temperature.

Evaluation of press formability for Ti-6Al-4V sheet at elevated temperature (티타늄 합금판재(Ti-6Al-4V)의 고온 성형성 평가)

  • Bae, M.K.;Park, J.G.;Kim, J.H.;Park, N.K.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.152-157
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    • 2009
  • Titanium alloy sheets have excellent specific strength and corrosion resistance as well as good performance at high temperature. Recently, titanium alloys are widely employed not only aerospace parts but also bio prothesis and motorcycle. But the database is insufficient of the titanium alloy for press forming process. In this study, the effect of temperature on the forming limit diagram was investigated for Ti-6Al-4V titanium alloy sheet through the Hocker's punch stretching test at elevated temperature. Experimental results obtained in this study can provide a database for development of press forming process at elevated temperature of Ti-6Al-4V titanium alloy sheet. From the experimental studies it can be concluded that the formability of Ti-6Al-4V titanium alloy sheet is governed by the ductile failure for the testing temperature below and vice versa neck-induced failure above the recrystalization temperature $0.5T_m$. The formability of Ti-6Al-4V titanium alloy sheet at $750^{\circ}C$ increases about 7 times compared with that at room temperature.

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Machining Characteristics of Ti-6Al-4V Thread (Ti-6Al-4V 티타늄 합금나사의 절삭 특성)

  • Kim, Hyung-Sun;Choi, Jong-Guen;Kim, Dong-Min;Lyu, Min-Young
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.5
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    • pp.514-520
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    • 2009
  • Titanium is one of the most attractive materials due to their superior properties of high specific strength and excellent corrosion resistance. The applications in aerospace and medical industries demand machining process more frequently to obtain more precise products. Machining of titanium is faced with strong challenges such as increased component complexity i.e. airframe components manufacturing processes. The machining cost on titanium have traditionally demanded high cutting tool consumable cost and slow machining cycle times. Similarly, the high wear of the cutting tools restricts the cutting process capabilities. Titanium screws applied to fasten parts In the several corrosion environment. In the thread cutting of titanium alloys, the key point for successful work is to select proper cutting methods and tool materials. This study suggests a guidance fur selecting the cutting methods and the tool materials to improve thread quality and productivity. Some experiments investigate surface roughnesses, cutting forces and tool wear with change of various cutting parameters including tool materials, cutting methods, cutting speed. As the results, the P10 type insert tip was assured of the best for thread cutting of Ti-6Al-4V titanium alloy. Also the initial depth of infeed was desirable to use the value below 0.5mm as the uniform cutting area method is applied.

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Studies on the Thermal Analysis of Flame Retardant Fibers(III) -On the Adsorption of Ti Complexes on Silk and its Effect on Flame Redardancy- (난연화 섬유의 열분석에 관한 연구 (제3보) -견섬유의 티탄염 흡착거동과 방염효과-)

  • 허영우;송석규
    • Textile Science and Engineering
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    • v.13 no.1
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    • pp.33-41
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    • 1976
  • Titanium salt adsorption behaviors in the citric acid aqueous solution on domestic silk fabric and its effects on flame retardancy were examined. For the evaluation of flame retardancy, the following methods were used: 45$^{\circ}$ angel burn test, thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The results are as follow. 1. The adsorbed amount of titanium salt on silk fabric is varied to some extent with the treating conditions, thus, salt increased with increassing of treating temperature, time and citric acid concentration of solution. 2. Titanium salt are effectual for flame retardancy on silk at smaller add-on as on wool but Zirconium salt are not so effectual as titanium salt. 3. It has been observed that titanium salt lower the onset temperature of phyrolysis and in crease char amount after pyrolysis. 4. The peaks of pyrolysis velocity (dw/dt) obtained from plots of dw/dt vs temperature were some what shifted to higher temperature in contrast with that of untreated silk. 5. All the silk fabrics show an initial endothermic reaction at about 100$^{\circ}C$ on account of the evaporation of absorbed water. The second endothermic peaks appear at 310∼315$^{\circ}C$ according to the titanium salt add-on amount. 6. It have the tendency to decrease the specific reaction rate constant and activation energy according to the titanium treatment. Its values are decreased with the increase of the titanium salt add-on.