• 한국주조공학회지
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• 제23권2호
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• pp.77-85
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• 2003

Some alloying elements such as Cr, B, Ti and Si were added individually or as a mixture to Fe-30 at.%Al alloys. The alloys were melted using an arc furnace and then heat-treated for homogenization at 1000$^{\circ}C$ for 7 days and followed by rolling at 1000$^{\circ}C$. The alloying elements on rolling characteristics were investigated by the microstructures and fracture mode before and after rolling. The microstructures before rolling showed that all of the alloys had equiaxed grains. On the other hand, the microstructures of rolling plane as well as its perpendicular plane became elongated after rolling. The alloys such as Fe-30Al, Fe-30Al-3Ti, Fe-30Al-0.5B, Fe-30Al-5Cr and Fe-30Al-3Ti-0.5B revealed better rolling behaviour from the point that intergranular and cleavage fractures were not fundamentally occurred. But the addition of 5Ti or 3Si to Fe-Al alloys had detrimental effects. The Ti-added alloy system such as Fe-30Al-5Ti, Fe-30Al-5Ti-5Cr, Fe-30Al-3Ti-5Cr and Fe-30Al-5Ti-0.5B were cracked through grain and showed cleavage fracture. The Si-added alloy system such as Fe-30Al-5Si, Fe-27Al-3Si and Fe-27Al-5Cr-3Si were cracked along the grain boundary and showed intergranular fracture. $DO_3{\leftrightarrow}B_2$ transition temperature of Fe-30at.%Al alloy was 520$^{\circ}C$, whereas the addition of 3Ti and 3Ti+0.5B comparably increased the temperature to 797 and 773$^{\circ}C$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.19-19
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• 2009

TiNxOy/TiNx multilayer thin films with a high resistance (~ k$Omega$) were deposited on SiO2/Si substrates at room temperature by sputtering. The TiNx thin films show island and smooth surface morphology in samples prepared by dc and rf magnetron sputtering, respectively. TiNxOy/TiNx multilayer has been developed to control temperature coefficient of resistance (TCR) by the incorporation of TiNx layer (positive TCR) inserted into TiNxOy layers(negative TCR). Electrical and structural properties of sputtered TiNxOy/TiNx multilayer films were investigated as a function of annealing temperature. In order to achieve a stable high resistivity, multilayer films were annealed at various temperatures in oxygen ambient. Samples annealed at 700 oC for 1 min exhibit a good TCR value and a stable high resistivity.

• 한국표면공학회지
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• 제39권6호
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• pp.245-249
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• 2006

In this study, ternary Ti-Mo-N and new quaternary Ti-Mo-Si-N coatings were synthesized on steel substrates(AISI D2) and Si wafers by a hybrid coating system of arc ion plating (AIP) using Ti target and d.c. magnetron sputtering technique using Mo and Si targets in $N_2/Ar$ gaseous mixture. Ternary Ti-Mo-N coatings were substitutional solid-solution of (Ti, Mo)N and showed maximum hardness of approximately 30 GPa at the Mo content of ${\sim}10$. %. The Ti-Mo-Si-N coating with the Si content of 8.8 at. % was a composite consisting of fine (Ti, Mo)N crystallites and amorphous $Si_3N_4$ phase. The hardness of the Ti-Mo-Si(8.8 at. %)-N coatings exhibited largely increased hardness value of ${\sim}48$ GPa due to the microstructural evolution to the fine composite microstructure and the refinement of (Ti, Mo)N crystallites. The average friction coefficient of the Ti-Mo-Si-N coatings largely decreased with increase of Si content. The microstructures of Ti-Mo-Si-N coatings were investigated with instrumental analyses of XRD, XPS, and HRTEM in this work.

• 한국진공학회지
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• 제5권2호
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• pp.147-155
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• 1996

Optical properties of $TiO_2/M/Ag/M/TiO_2$ films have been changed with the diffusion barrier metal M. Optimum opticla properties of $TiO_2/M/Ag/M/TiO_2$ as the transparent heat mirror film, could be obtained with Ti among diffusion barrier metals of Ti, Cu, Zr and Al. $TiO_2/M/Ag/M/TiO_2$ film, which was fabricated by sputtering of 18 nm-thick $TiO_2$ and Ag, and 4nm-thick Ti, showed maximum transimittance of 89% at visible wavelength and infrared reflectance of 97% at wavelength of 3000 nm. Optical properties of this film was not degraded by Xenon-sunshine weather test for 240 hours. For specimens with barrier layers of Cu, Zr, and Al, degradation of optical properties by weather test was increased in a sequence of films with Cu, Zr, and Al barrier layers.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.344-350
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• 2010

The improved photocatalytic performance of a carbon/$TiO_2$ composite was studied for the Bisphenol A (BPA) decomposition. Titanium tetraisopropoxide (TTIP) and a rice husk from Korea were heterogeneously mixed as the titanium and carbon sources, respectively, for 3 h at room temperature, and then thermally treated at $600^{\circ}C$ for 1 h in $H_2$ gas. The transmission electron microscopy (TEM) images revealed that the bulk carbon partially covered the $TiO_2$ particles, and the amount that was covered increased with the addition of the rice husk. The acquired carbon/$TiO_2$ composite exhibited an anatase structure and a novel peak at $2{\theta}=32^{\circ}$, which was assigned to bulk carbon. The specific surface area was significantly enhanced to 123~164 $m^2/g$ in the carbon/$TiO_2$ composite, compared to $32.43m^2/g$ for the pure $TiO_2$. The X-ray photoelectron spectroscopy (XPS) results showed that the Ti-O bond was weaker in the carbon/$TiO_2$ composite than in the pure $TiO_2$, resulting in an easier electron transition from the Ti valence band to the conduction band. The carbon/$TiO_2$ composite absorbed over the whole UV-visible range, whereas the absorption band in the pure$TiO_2$ was only observed in the UV range. These results agreed well with an electrostatic force microscopy (EFM) study that showed that the electrons were rapidly transferred to the surface of the carbon/$TiO_2$ composite compared to the pure $TiO_2$. The photocatalytic performance of the BPA removal was optimized at a Ti:C ratio of 9.5:0.5, and this photocatalytic composite completely decomposed 10.0 ppm BPA after 210 min, whereas the pure $TiO_2$ achieved no more than 50% decomposition under any conditions.

• 대한치과기공학회지
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• 제33권4호
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• pp.263-270
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• 2011

Purpose: The grindability of binary Ti-X%Zr(X=10,20,40) alloys in order to develop a Ti alloy with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-Zr alloys were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at circumferential speeds(12000,18000,25000 or 30000rpm) by applying a force(200gr). Grinding rate was evaluated by measuring the amount of metal volume removed after grinding for 1 minute and the volume ratio of metal removed compared to the wheel material lost, which was calculated from the diameter loss (grinding ratio). Experimental datas were compared to those for cp Ti(commercially pure titanium) and Ti-6%Al-4%V alloy were used controls. Results: It was observed that the grindability of Ti-Zr alloys increased with an increase in the Zr concentration. More, they are higher than cp Ti, particularly the Ti-20%Zr alloy exhibited the highest grindability at all circumferential speeds. There was significant difference in the grinding rate and grinding ratio between Ti-20%Zr alloy and cp Ti at any speed(p<0.05). Conclusion: By alloying with Zr, the Ti exhibited better grindability at all circumferential speeds. the Ti-20%Zr alloy has a great potential for use as a dental machining alloy.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.130-130
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• 2018

산업 발전으로 특수합금들이 발달함에 따라 가공할 수 있는 새로운 절삭공구소재들이 개발되어지고 있다. 또한 공구소재보다 코팅개발이 상대적으로 더욱 효과적이기 때문에 코팅 기술 개발이 활발히 진행되고 있다. 일본에서는 새로운 코팅층 물질 개발보다는 기존의 코팅물질을 조합하거나 개량하여 성능을 향상시키는 추세이다. TiAlSiN 박막은 스퍼터링과 음극 아크 소스를 이용한 hybrid 공정을 이용하여 코팅 후 특성을 평가하였다. Ti-50at.%Al의 조성을 갖는 TiAl 합금 타겟은 음극 아크 소스를 이용하여 코팅하였다. 공정 가스는 Ar과 N2의 혼합 가스를 사용하였으며 공정 압력은 $1.0{\times}10^{-2}Torr$이었다. 음극 아크 소스에 인가된 전류는 70 A이었다. TiAlSiN 박막의 Si 함량을 조절하기 위해서 Si은 스퍼터링으로 코팅하였으며 스퍼터링 소스에 인가되는 전력의 세기를 0.29 kW ~ 1.05 kW까지 변화시켰다. 코팅 공정에 사용된 Si 타겟의 순도는 4N이다. TiAlSiN 박막의 Si 함량은 스퍼터링 전력에 따라 3.4 ~ 14.4at%까지 변화하는 것을 확인하였다. TiAlSiN 코팅층의 경도는 초미소 경도계를 이용하여 측정하였으며, Si 함량이 증가하면 TiAlSiN 박막의 경도도 증가하는 것을 확인할 수 있다. TiAlSiN 박막의 Si 함량이 9.2at.%일 때 3000 Hv 이상의 경도를 보였다. TiAlSiN 코팅층의 Si 함량이 14.4at%로 높아지면 경도가 낮아지는 현상을 보였다. TiAlSiN 박막의 Si 함량이 증가하면 내산화성이 향상되는 현상을 확인할 수 있었다.

• 한국표면공학회지
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• 제35권6호
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• pp.391-400
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• 2002

Corrosion characteristics of Ti, Ti/Cr coated and plasma-nitrided surface for stainless steel containing Ti have been studied. Stainless steels containing 0.09-0.92wt% Ti were fabricated by using vacuum furnace and solutionized for 1hr at 105$0^{\circ}C$. Ti and Cr coatings were done on solutionized stainless steel surface by EB-PVD. The Ti coated specimen were coated by Cr and were nitrided by plasma at $450^{\circ}C$ for 5hr. Microstructure and phase analysis were performed using SEM, OM and EDX. Corrosion behavior of the coated specimen was investigated by electrochemical test. The coated surface was of fine columnar structure. The Ti/Cr coated surface was denser than the Ti coated and the Ti coated-nitrided surfaces. The corrosion and pitting potential increased in proportion to the Ti content, coating temperature, coating thickness and formation of stable oxide film. The current density in active and passive region decreased in the case of Ti/Cr coated sample and Ti coated-nitrided samples. Especially the plasma nitrided specimen after Ti coating have a good corrosion resistance compared with the Ti coated specimen. The number and size of pits decreased as Ti content of matrix increased.

• 한국표면공학회지
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• 제36권1호
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• pp.89-98
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• 2003

Corrosion characteristics of Ti, Ti/Cr coated and plasma-nitrided surface for stainless steel containing Ti have been studied. Stainless steels containing 0.09-0.92wt% Ti were fabricated by using vacuum furnace and solutionized for 1hr at $1050^{\circ}C$. Ti and Cr coatings were done on solutionized stainless steel surface by EB-PVD. The Ti coated specimen were coated by Cr and were nitrided by plasma at $450^{\circ}C$ for 5hr Microstructure and phase analysis were performed using SEM, OM and EDX. Corrosion behavior of the coated specimen was investigated by electrochemical test. The coated surface was of fine columnar structure. The Ti/Cr coated surface was denser than the Ti coated and the Ti coated-nitrided surfaces. The corrosion and pitting potential increased in proportion to the Ti content, coating temperature, coating thickness and formation of stable oxide film. The current density in active and passive region decreased in the case of Ti/Cr coated sample and Ti coated-nitrided samples. Especially the plasma nitrided specimen after Ti coating have a good corrosion resistance compared with the Ti coated specimen. The number and size of pits decreased as Ti content of matrix increased.

• 한국진공학회지
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• 제1권1호
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• pp.67-72
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• 1992

고에너지 반사 전자회절기(RHEED) 및 투과전자현미경(HRTEM)을 이용하여 Si(111)-7 $\times$ 7 면에서의 Ti 박막의 성장 mode와 Si(111) 면에서의 C54 TiSi2의 정합성장 을 조사하였다. 초고진공에서 Si(111)-7 $\times$ 7 표면에 상온에서 Ti를 증착하면 Ti/Si 계면에 서 비정질의 Ti-Si 중간막이 먼저 형성되고 그 위에 Ti 박막은 다결정으로 성장하였다. 160ML의 Ti를 증착한 시료를 초고진공 내에서 75$0^{\circ}C$로 10분 열처리하면 C54 TiSi2가 정합 성장하였으며 이는 HRTEM 격자상 및 TED Pattern으로 확인할 수 있었다. TiSi2/Si(111) 시 료를 다시 $900^{\circ}C$로 가열하면 TiSi2위에 단결정 Si층이 [111] 방향으로 성장하였다.