• 한국재료학회지
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• 제12권11호
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• pp.889-893
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• 2002

The reactions of $Cu/Ti/SiO_2$ structures at temperatures ranging from 200 to $700^{\circ}C$ have been studied for various Ti thicknesses. The reaction products initially formed, at around $300^{\circ}C$, were a series of Cu-Ti intermetallics ($Cu_3$Ti/CuTi) with the oxygen dissolved in the Ti moving from the compounds into the remaining unreacted Ti. At $500^{\circ}C$, the $Cu_3$Ti was converted into Cu-rich intermetallics, $Cu_4$Ti, which grew at the expense of the CuTi due to the increased oxygen content in the Ti. In addition, the outdiffusion of Ti, to the Cu surface, and the $Ti-SiO_2$ reactions, caused an abrupt increase in the oxygen content in the Ti layer, which placed thermodynamic restraints on further Ti reactions. Furthermore, thinner Ti layers showed a higher increasing rate of oxygen accumulation for the same consumption of Ti, which led to significantly reduced Ti consumption. The $SiO_2$ film under the Ti diffusion barrier was more easily destroyed with increasing Ti thickness.

• 한국세라믹학회지
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• 제35권8호
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• pp.791-794
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• 1998

• 한국재료학회지
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• 제11권3호
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• pp.203-206
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• 2001

SrTiO$_3$첨가량 및 소결온도에 따른 YIG 소결체의 미세구조 및 자기적 특성변화에 대하여 조사하였다. 소량의 SrTiO$_3$소결재를 첨가한 결과 소결체의 격자상수는 약간 증가하였으며, 이는 소결시 $Y^{+3}$, Fe$^{+3}$이온이 이온반경이 상대적으로 큰 Sr$^{+2}$, Ti$^{+4}$이온으로 치환되었기 때문인 것으로 추정된다. SrTiO$_3$소결재를 0.2mo1% 첨가하고, 142$0^{\circ}C$에서 소결한 소결체의 밀도는 이론밀도의 98%이상의 치밀화를 얻을 수 있었다. 상온에서의 포화자화값(M$_s$)은 SrTiO$_3$소결재의 첨가량이 증가함에 따라 약간 감소하였으나 큰 변화는 없었다. 더욱이 온도에 따른 보자력 (H$_c$)의 변화는 없었다.

• 대한치과기공학회지
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• 제35권4호
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• pp.295-302
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• 2013

Purpose: The grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys in order to develop Ti alloys for dental applications with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-10%Zr-X%Cr(X=0,1,3) 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 one of the four rotational speeds of the wheel (12000, 18000, 25000 or 30000rpm) by applying a force(100gf). Grindability was evaluated by measuring the amount of metal volume removed per minute(grinding rate) 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 the results with those of cp-Ti(commercially pure titanium) Results: It was observed that the grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys increased with an increase in the Cr concentration. More, they are higher than cp-Ti, particularly the Ti-10%Zr-3%Cr alloy exhibited the highest grindability at all rotational speeds except 12000rpm. There was significant difference in the grinding rate and grinding ratio between Ti-10%Zr-3%Cr alloy and cp-Ti at all rotational speeds(p<0.05). Conclusion: The Ti-10%Zr-3%Cr alloy exhibited better grindability at high rotational speeds, great potential for use as a dental machining alloy.

• 공업화학
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• 제33권1호
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• pp.64-70
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• 2022

본 연구에서는 NH₃-SCR에서 VWTi촉매의 저온 탈질효율 증진을 위해 Sb을 첨가하여 실험을 수행하였으며 Sb 첨가에 있어 다양한 소성온도(400~700 ℃)에서 제조하였다. NH₃-SCR 실험 결과 Sb 소성온도 500~600 ℃에 해당하는 VWSbTi(500)와 VWSbTi(600) 촉매가 300 ℃ 이하의 저온에서 가장 우수한 탈질성능을 나타냈으며, 소성온도에 따른 물리화학적 특성을 확인하고자 BET, XRD, Raman, XPS, H₂-TPR, NH₃-TPD 분석을 수행하였다. VWSbTi(500)와 VWSbTi(600)의 경우 W=O종의 생성에 따라 암모니아 산점이 증가하였으며 텅스텐의 전자밀도 증가에 따른 우수한 redox 특성으로 저온에서 우수한 활성을 나타내었다. 또한 VWSbTi(700)의 경우 V₂O₅ 결정구조가 형성되어 활성이 저하됨에 따라 Sb 첨가과정에 있어 최적의 소성온도를 확인하였다.

• 한국세라믹학회지
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• 제39권4호
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• pp.413-419
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• 2002

$Al_2O_3$/TiC/SiC, $Al_2O_3$/SiC 및 $Al_2O_3$/TiC 복합체들을 고온가압소결로 제조하여 이들의 균열저항거동과 기계적 성질을 비교해 보았다. $Al_2O_3$에 $0.8{\mu}m$의 TiC가 30vol% 첨가된 $Al_2O_3$/TiC는 단일체 $Al_2O_3$와 비슷한 균열저항거동을 보이며 파괴인성은 전반적으로 10% 이내의 증가를 보이는데 그쳤지만 강도는 약 30% 증가하였다. $Al_2O_3$에 $3{\mu}m$ SiC가 30vol% 첨가된 $Al_2O_3$/SiC는 SiC 입자의 균열 접속으로 인해 증가하는 균열저항거동을 뚜렷이 보이면서 파괴인성이 긴 균열에서 약 75% 증가하였으나 강도는 다소 감소했다. $Al_2O_3$/TiC에 SiC 입자가 30 vol% 첨가된 $Al_2O_3$/TiC/SiC 복합체의 경우 단일체 $Al_2O_3$에 비해 긴 균열 거리에서 파괴인성이 50% 이상 증가된 6.6 MP${\cdot}\sqrt{m}$에 이르렀으며 강도 값도 약 20% 상승하였다. 그러나 큰 SiC 입자의 첨가로 인해 TiC 입자만 첨가된 $Al_2O_3$/TiC 복합체보다는 강도가 다소 낮았다. 또한 SiC 입자만 첨가된 $Al_2O_3$/SiC 복합체보다는 파괴인성이 다소 낮았는데, 이는 작은 TiC 입자들이 SiC 입계를 거칠게 만들어 균열접속을 일으키는 SiC 입자의 뽑힘 현상을 방해하였기 때문이다.

• 대한치과기공학회지
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• 제23권2호
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• pp.223-230
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• 2002

Pure titanium and Ti6Al4V alloy have been mainly used as implant materials but the cytotoxicity of V, neurotoxicity of Al resulting in Alzheimer disease had been reported. This paper was described the influence of composition of Ti-Nb alloys with 3 wt%Nb, 20 wt%Nb on the microstructure and corrosion resistance. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at $1000^{\circ}C$ for 24hr. The alloys were rolled in $\beta$ and ${\alpha}+{\beta}$ regions. The corrosion resistance of Ti alloys were evaluated by potentiodymic polarization test in 0.9% NaCl and 5% HCl solutions. The results can be summarized as follows: 1. The microstructure was transformed from $\alpha$ phase to ${\alpha}+{\beta}$ phase by adding Nb 2. The hardness of Ti-20Nb alloy was greater than Cp- Ti, Ti-3Nb alloy. 3. The corrosion resistance of Ti-20Nb alloy was better than that of Cp-Ti, Ti-3Nb alloy in 0.9%NaCl and 5%HCl solutions.

• 열처리공학회지
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• 제10권2호
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• pp.138-149
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• 1997

TiN and AlN are ceramic materials with extensive applications due to its excellent mechanical and chemical properties at elevated temperature. The purpose of this research is to develop the method for the synthesis of ternary nitride powder, titanium-aluminum-nitrogen system, which have an excellent property of both TiN and AlN. The ternary nitride such as $Ti_3AlN$, $Ti_2AlN$ and $Ti_3Al_2N_2$ can be synthesized by the interdiffusion nitriding method in Ar gas, however, the ternary nitride coexist with TiN, AlN, $Ti_3Al$ and ${\alpha}$-Ti. The ternary nitride are stable below $1400^{\circ}C$, but these are gradually decomposed into TiN, $Ti_3Al$ and AlN above $1400^{\circ}C$. The thermal oxidation characteristics of the Ti-Al-N compound synthesized by the interdiffusion nitriding method is superior to that of the TiN+AlN mixed powder, and the oxidation for both materials show the differential behaviors.

• 한국수소및신에너지학회논문집
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• 제3권2호
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• pp.25-33
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• 1992

With the aim to obtain $TiO_2$ films with an increased photorespones and absorbance in the visible region of the solar spectrum, the direct oxidation of titanium alloys were performed. In this study, $Ti-Ga_2O_3$ alloy was prepared by mixing, pressing and arc melting of appropriate amounts of titanium and $Ga_2O_3$ powder. Electrochemical measurements were performed in three electrode cell using electrolyte of 1M NaOH solution. The oxide films on $Ti-Ga_2O_3$ alloy was composed of $Ti_2O$, TiO, $TiO_2$, $Ga_2TiO_5$. The free energy efficiency (${\eta}e$) of $Ti-Ga_2O_3$ oxide films had 0.8~1.3 % and were increased with the increase of $Ga_2O_3$ content up to 10wt %. The onset potential ($V_{on}$) had -0.8V~0.9V ranges and were shifted to anodic direction with the increase of $Ga_2O_3$ content. The spectral response of Ti-$Ga_2O_3$ oxides were similar to the response of the $TiO_2$ and their $E_g$ were observed to 2.90~3.0eV. Variations of onset potential($V_{on}$) associated with electrolyte pH were -59mV/pH. This probably reflects the nature of the bonding of $OH^-$ ion to the $TiO_2$ surface, a common phenomena in the transition-metal oxides.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.286-287
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• 2006

Barium titanate ($BaTiO_3$) glycolate particles were synthesized at temperature as low as $100^{\circ}C$ through glycothermal reaction by using $Ba(OH)_2{\cdot}8H_2O$ and amorphous titanium hydrous gel as precursors and ethylene glycol as solvent. The particle size and morphology of $BaTiO_3$ glycolate powders can be controlled by varying the reaction conditions such as the reaction temperature and Ba:Ti molar ratio of starting precursors. After glycothermal treatment at $220^{\circ}C$ for 24 h in 1.25:1(Ba:Ti), the average particle size of the $BaTiO_3$ glycolate powder was about 200-400 nm and low agglomeration. $BaTiO_3$ powders were formed by heat-treating the glycolate powder in air at $500-1000^{\circ}C$. As a result, the size of $BaTiO_3$ crystallites changed from around 50-300 nm. It is also demonstrated that the size and shape of $BaTiO_3$ particles investigated as a function of calcination temperature. The $BaTiO_3$ particles obtained from optimum synthesis condition were pressed, sintered and measured for the dielectric property. The $BaTiO_3$ ceramics sintered at $1250^{\circ}C$ for 2 h had 98 % of theoretical density. The ceramics have an average grain size of about $1\;{\mu}m$ and displays the high dielectric constant (~3100) and low dielectric loss (<0.1) at room temperature.