• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.291-304
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• 1997

The purposes of this study were to evaluate the changes in root canal configuration with canal instrumentation using different file types and techniques and to investigate most appropriate instrumentation technique in maintaining the original canal configuration with different file types. Fifty curved mesiobuccal or distobuccal canals of extracted human maxillary molar teeth were instrumented using a step-back technique with stainless steel K-files or nickel-titanium K-files, a crown-down pressureless technique with stainless steel K-files or nickel-titanium K-files and nickel-titanium engine-driven files. Radiographs were taken before and after instrumentation using a specially designed device that allowed for the pre-and postinstrumentation canals to be taken with the same X-ray angulation. Magnified X-ray images on a magnifier screen were traced and post instrumentation canal images were compared with the preinstrumentation ones. Changes in canal curvature and the incidence of procedural accidents were analyzed. The results were as follows : Crown-down pressureless technique with nickel-titanium K-files and nickel-titanium engine-driven filing produced no significant changes in canal curvature (p>0.05), while the step-back technique with stainless steel K-files or nickel-titanium K-files (p<0.01) and the crown-down pressureless technique with stainless steel K-files (p<0.05) produced significant changes. With nickel-titanium K-file, crown-down pressureless technique produced significantly less changes in canal curvature than step-back technique (p<0.05), while there was no significant difference between techniques with stainless steel K-files (p>0.05). File types exerted no significant influences in the changes of canal curvature both in the step-back technique and crown-down pressureless technique (0>0.05). Regardless of the file types used, step-back technique produced more procedural accidents such as ledge or elbow formation, apical zipping and apical transportation than the crowndown pressureless technique and nickel-titanium engine-driven filing. Both with stainless steel K-files and with nickel-titanium K-files, the incidence of apical extrusion of canal debris was higher in step-back technique than in crown-down pressureless technique.

• 공업화학
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• 제4권1호
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• pp.64-74
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• 1993

국내 부존 함티탄자철광으로부터 염화티타늄($TiCl_4$)을 제조키 위해 함티탄자철광의 arc-smelting으로부터 얻어지는 titanium slag의 유동층 염소화 반응을 조사하였다. Titanium slag의 유동층 염소화반응에 적절한 반응조건은 반응 온도 $950^{\circ}C$, 반응시간 90분, 염소가스의 유속 3.0cm/sec, titanium slag에 대한 petroleum coke의 무게비 0.18, 그리고 titanium slag 및 petroleum coke의 입자의 평균직경은 각각 $44.6{\mu}m$, $67.9{\mu}m$였다. 위 조건하에서 titanium slug 중의 97.07%의 티타늄이 염소화 되었으며 제조된 염화티타늄($TiCl_4$)의 순도는 96.2%였다.

• Journal of Welding and Joining
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• 제31권2호
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• pp.16-20
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• 2013

Titanium and its alloys have been widely using in the various field of industry application due to high corrosion resistant properties and mechanical properties. Titanium is highly reactive in the high temperature state and the formation of titanium oxide and porosities in the nuggets of fusion welding will results in the degradation of the mechanical properties. For this reason the studies of friction stir welding for titanium have been investigated recently. The FSW zones of titanium were classified by the weld nugget (WN), the linear transition boundary (TB) and the heat affected zone (HAZ). The WN along with titanium parent was characterized by the presence of twins and dislocations. The average grain size and hardness of WN has been changed according to heat input. The grain refinement resulted from the FSW increased the hardness in the stir zone. Sound dissimilar joints between SUS 304 and CP-Ti were achieved using an advancing speed of 50 mm/min and rotation speeds in the range of 700-1100 rpm. Aluminum 1060 and titanium alloy Ti-6Al-4V plates were lap joined by friction stir welding, hence the ultimate tensile shear strength of joint reached 100% of Al 1060. Mg alloy and Ti were successfully butt joined by inserting a probe into the Mg alloy plate with slightly offsetting. But Ti-Al intermetallic compound layers formed at the interface of these joints.

• Journal of Periodontal and Implant Science
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• 제31권2호
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• pp.333-344
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• 2001

The present study was performed to evaluate the effect of tetracycline - HCl on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface and titanium plasma-sprayed surface were utilized. Implant surface was rubbed with 50mg/ml tetracycline - HCl solution for 1 min., $1\frac{1}{2}\;min$., 2 min., $2\frac{1}{2}\;min$. and 3min. respectively in the test group and with saline for 1 min. in the control group. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. Pure titanium machined surfaces conditioned with saline for 1 min., showed a few shallow grooves and ridges and were less irregular. 2. Pure titanium machined surfaces conditioned with 50mg/ml tetracycline - HCl solution showed more irregular and corrosive surfaces compared to the control group irrespective of the application time of tetracycline - HCl solution. 3. Titanium plasma-sprayed surfaces conditioned with saline for 1 min., were deposited with round amorphous particles and showed round or irregular pores that can be connected to each other. 4. The irregularity of titanium plasma-sprayed surfaces conditioned with 50mg/ml tetracycline - HCl solution was lessened and the flattened areas were wider relative to the application time of tetracycline - HCl solution. 5. Titanium plasma-sprayed surfaces conditioned with tetracycline - HCl solution for 1 min. and $1\frac{1}{2}\;min$. were very similar to that of the control group, but the surfaces conditioned for 2 min., $2\frac{1}{2}\; min$. and 3 min. were changed. In conclusion, pure titanium machined surfaces were changed irrespective of the application time of tetracycline - HCl solution. And titanium plasma-sprayed surfaces conditioned with tetracycline - HCl solution began to be changed from $1\frac{1}{2}\;min$. This results will be applicable to the regenerative procedures for peri-implantitis treatment.

• 한국주조공학회지
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• 제41권2호
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• pp.139-143
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• 2021

타이타늄 합금 중 페로-타이타늄은 철강 업계에서 철강과 스테인리스강을 생산하는데 사용되는 주요 첨가물이다. 본 연구에서는 고품질의 페로-타이타늄 합금을 주조하기 위해 경제적인 면을 고려한 저비용 타이타늄 스크랩을 활용하고자 하였다. 먼저 재활용 타이타늄 스크랩의 표면에 형성되어 있는 절삭유 및 불순물을 제거하기 위한 최적의 전처리 공정을 연구하였다. 일반적인 세척 방법인 산이나 유기용제는 세척이 용이하나 환경적으로 문제가 되므로 친환경적인 방법을 고안하여 적용하고자 하였다. 또한, 타이타늄 스크랩을 활용하여 고품질의 페로-타이타늄 잉곳을 제조하고 성분 분석을 통해 불순물과 특성을 상용 소재 규격과 비교 분석하였다.

• Archives of Plastic Surgery
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• 제43권1호
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• pp.84-87
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• 2016

Titanium micro-mesh implants are widely used in orbital wall reconstructions because they have several advantageous characteristics. However, the rough and irregular marginal spurs of the cut edges of the titanium mesh sheet impede the efficacious and minimally traumatic insertion of the implant, because these spurs may catch or hook the orbital soft tissue, skin, or conjunctiva during the insertion procedure. In order to prevent this problem, we developed an easy method of inserting a titanium micro-mesh, in which it is wrapped with the aseptic transparent plastic film that is used to pack surgical instruments or is attached to one side of the inner suture package. Fifty-four patients underwent orbital wall reconstruction using a transconjunctival or transcutaneous approach. The wrapped implant was easily inserted without catching or injuring the orbital soft tissue, skin, or conjunctiva. In most cases, the implant was inserted in one attempt. Postoperative computed tomographic scans showed excellent placement of the titanium micro-mesh and adequate anatomic reconstruction of the orbital walls. This wrapping insertion method may be useful for making the insertion of titanium micro-mesh implants in the reconstruction of orbital wall fractures easier and less traumatic.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.36.2-36.2
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• 2011

Titanium and its alloys have been widely used for orthopedic implants because of their good biocompatibility. We have previously shown that the crystalline titania layers formed on the surface of titanium metal via anodic oxidation can induce apatite formation in simulated body fluid, whereas amorphous titania layers do not possess apatite-forming ability. In this study, hot water and heat treatments were applied to transform the titania layers from an amorphous structure into a crystalline structure after titanium metal had been anodized in acetic acid solution. The apatite-forming ability of titania layers subjected to the above treatments in simulated body fluid was investigated. The XRD and SEM results indicated hot water and/or heat treatment could greatly transform the crystal structure of titania layers from an amorphous structure into anatase, or a mixture of anatase and rutile.The abundance of Ti-OH groups formed by hot water treatment could contribute to apatite formation on the surface of titanium metals, and subsequent heat treatment would enhance the bond strength between the apatite layers and the titanium substrates. Thus, bioactive titanium metals could be prepared via anodic oxidation and subsequent hot water and heat treatment that would be suitable for applications under load-bearing conditions.

• 한국진공학회지
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• 제6권S1호
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• pp.1-15
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• 1997

Titanium oxide films were prepared by ion beam enhanced deposition where the films were synthesized by deposition titianium atoms and simultaneously bombarding with xenon ion beam at an energy of 40 keV in an $O_2$ environ,ent. Structure and composition of titanium oxide films were investigated by X-ray Doffractopm (XRD) Ritjerfprd Backscattering Spectroscopy (RBS) and X-ray Diffraction(XRD) Rutherford Backscattering Spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS) The results show that thestructure of the prepared films exhibit a rutile phase structure wit high(200) orientation and the O/Ti ratio of the titanium oxide films was about 2:1 XPS anlysis shows that $Ti^{2+},Ti^{3+}\;and\;Ti^{4+}$ chemical states exist on the titanium oxide films. the blood compatibility of the titanium oxide films was studied by measurements of blood clotting time and platelet adhesion. The results show that the anticoagulation property of titanium oxide films improved significantly and better than that of LTI-carbon which was widely used to fabricate artificial heart valve.

• Journal of Advanced Marine Engineering and Technology
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• 제32권2호
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• pp.315-322
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• 2008

Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and creep properties in high temperature, which make them using many various fields of application. Especially, pure titanium, which has outstanding resistance for the stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion, brings out to the best material for the heat exchanger, ballast tank, desalination facilities, and so on. Responding to these needs, welding processes for titanium are also being used GTAW, GMAW, PAW, EBW, LBW, resistance welding and diffusion bonding, etc. However, titanium is very active and highly susceptible to embrittlement by oxygen, nitrogen, hydrogen and carbon at high temperature, so it needs to shield the weld metal from the air and these gases during welding by non-active gas. In this study, it was possible to get sound beads without humping and spatter with a decrease of peak power according to increase of pulse width, change of welding speed and overlap rate for heat input control, and shield conditions at pulsed laser welding of titanium plates for Lap welding.

• 분석과학
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• 제12권6호
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• pp.509-514
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• 1999

Titanium(IV) isoproxide에 유기첨가제로 아세트산을 첨가하여 단일성분계인 치환된 titanium(IV) isoproxide를 합성한다. 합성된 titanium 착화합물은 세가지 형태로 된 5배위 및 6배위의 구조로 존재함을 FT-IR, $^1H$ 및 $^{13}C$ NMR 그리고 UV-Vis 스펙트라로 확인하였다. 이 착물에 대한 가수분해 반응을 $^1H$-NMR spectroscopy를 이용해 관찰하였고 FT-IR spectroscopy로 가수분해 및 건조시킨 후의 구조 변화를 관찰하여 보았으며 리간드의 존재 유무도 살펴보았다.