• 한국세라믹학회지
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• 제45권10호
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• pp.638-643
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• 2008

Biomimetic apatite formation and deposition behaviors of Ti-6Al-7Nb and Ti-6Al-4V plates in simulated body fluids(SBF) under various conditions were examined. In case of regular samples without collagen treatments the weight gain due to apatite precipitation on the surface in Ti-6Al-4V was found to be higher than in Ti-6Al-7Nb. In case of collagen-coated samples, the weight gain in Ti-6Al-4V continued to be higher than in Ti-6Al-7Nb, but the difference between the two became smaller. Both Ti-6Al-7Nb and Ti-6Al-4V samples with collagen coating exhibited an appreciable increase of weight gain, which may be caused by the interaction between collagen and $Ca^{+2}$ ions. The weight gain was found to be not much affected by the addition of collagen to SBF. The ill-defined granular structure in the presence of collagen can be associated with the increasing volume fraction of amorphous calcium phosphate.

• 대한치과기공학회지
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• 제27권1호
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• pp.19-25
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• 2005

Ti6Al4V alloy have been mainly used as implant materials. Ti-6Al-4V alloy instead of pure Ti is being widely used as biomaterials has some characteristics such as high fatigue strength, tensile strength. But it has been reported recently that vanadium component expresses cytotoxicity and carcinogenicity and aluminium component is related with dementia of Alzheimer type. In order to overcome their detrimental effects, $\beta$-phase stabilizer Nb was chosen in the present study, in addition Ta and Hf were added to Ti-40wt.%Nb alloy to improve its mechanical properties. This paper was described the influence of heat treatment of Ti-40Nb alloys with 2wt%Ta, 2wt%Hf on the mechanical properties. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at 1050$^{\circ}C$ for 24 hr. and then were aged after solution heat treat at $\alpha+\beta$ and $\beta$ regions. The mechanical properties of Ti alloys were analysed by hardness test, tensile test, elongation test and SEM test. The results can be summarized as follows: 1. The mechanical properties Ti-40wt.%Nb were improved when 2wt.% Ta and 2wt.%Hf were added. 2. The higher tensile strength value and elongation at solution heat treat was higher than solution heat treat and then were aged.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.196-197
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• 2005

The $ZnNb_2O_6$ ceramics with 3wt% CuO and $B_2O_2$(1,3,5wt%) were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $1000^{\circ}C\sim1050^{\circ}C$ for 3hr. in air. The structural properties were investigated with sintering temperature by XRD and SEM. Also, the microwave dielectric properties were investigated with sintering temperature. Increasing the sintering temperature, the peak of second phase ($Cu_3Nb_2O_8$) was increased. But no significant difference was observed as sintering temperature. In the $ZnNb_2O_6$ ceramics with 3wt% CuO and 5wt% $B_2O_3$ sintered at $1025^{\circ}C$ for 3hr, the dielectric constant, quality factor, temperature coefficient of the resonant frequency were 22.92, 20,271GHz, -14.27ppm/$^{\circ}C$, respectively.

• Nuclear Engineering and Technology
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• 제29권3호
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• pp.196-200
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• 1997

The variation of sintered density and fain size in ex-AUC, ex-ADU and granulated ex-ADU UO$_2$ pellets in which 0.1~1.0wt% Nb$_2$O$_{5}$ were doped were examined. Pellets were sintered in an atmosphere of H$_2$ at 1$700^{\circ}C$ for 4h. All the specimens tested shooed more than 94% T.D.(Theoretical Density). Sintered density decreased with increasing the amount of Nb$_2$O$_{5}$. Powder types had little influence on the sintered density. Pore size distribution was shifted to the larger ones as Nb$_2$O$_{5}$ was added. The increase of total pore volume and grain growth due to the addition of Nb$_2$O$_{5}$ were thought to be the cause of the sintered density decrease. The largest grain size was seen in the 1. 0wt% Nb$_2$O$_{5}$ doped ex-AUC UO$_2$ pellets. Their average size was 13.9 ${\mu}{\textrm}{m}$.m}$.

• 한국재료학회지
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• 제25권7호
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• pp.317-321
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• 2015

The effects of Nb doping on the crystal structure, microstructure, and dielectric ferroelectric and piezoelectric properties of $(Bi_{0.5}Na_{0.5})_{0.935}Ba_{0.065}Ti_{(1-x)}Nb_xO_3-0.01SrZrO_3$ (BNBTNb-SZ, with ${\chi}=0$, 0.01 and 0.02) ceramics have been investigated. X-ray diffraction patterns revealed that all ceramics have a pure perovskite structure with tetragonal symmetry. The grain size of the ceramics slightly decreased and a change in grain morphology from square to spherical shape was observed in the Nb-doped samples. The maximum dielectric constant temperature ($T_m$) increases with increasing amount of Nb; however, ferroelectric-relaxor transition temperature ($T_{F-R}$) and maximum dielectric constant (${\varepsilon}_m$) values decrease gradually. Nb addition disrupted the polarization hysteresis loops of the BNBT-SZ ceramics by leading a reduction in the remnant polarization coercive field and piezoelectric constant.

• 열처리공학회지
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• 제35권2호
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• pp.88-95
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• 2022

Titanium alloy for bio-medical applications have been developed to reduce the toxicity of alloying elements and avoid the stress-shielding effect which is caused by relatively high elastic modulus compared to bone. Ti-39Nb-6Zr (TNZ40) alloy of elastic modulus exhibits around 40 GPa in the case of beta single phase. However, the strength of this alloy is lower than the other types of titanium alloys. Many research found that adding oxygen to beta-titanium alloys is beneficial for improving the strength through solid solution strengthening. In this study, TNZ40 ingots with addition of O were prepared by an arc remelting process (Ti-39Nb-6Zr-0.16O (wt.%), Ti-39Nb-6Zr-0.26O (wt.%)). Thermo-mechanical processing (i.e., heat treatment, cold swaging and aging heat treatment) has been performed under various conditions. Therefore, the aim of this study is to investigate the effect of oxygen content and ω phase formation on microstructure and mechanical properties.

• 한국재료학회지
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• 제3권1호
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• pp.43-49
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• 1993

AI킬드한 극저탄소강에 Ti, Nb등의탄화물 또는 질화물 형성원소를 첨가하면 우수한 디프드로잉특성과 내시효성을 나타내는 강판을 얻을 수 있다고 알려져 있으므로 본 연구에서는 Ti및 Nb를 단독 또는 동시에 첨가하거나 B를 추가로 첨가한 고강도 극저탄소 강판을 제조하여 각각의재결정 집합조직과 기계적 성질을 측정비교하여 보았다. 역극점도에 나타난 집합조직강도의 변화를 조사한 결과 어닐링처리에 의하여 (100)면 강도와 (111)면 강도의 변화가 가장 많이 나타난 것은 Nb첨가강이며, Nb와 Ti를 단독으로 첨가한 강과 Ti를 단독으로 첨가한 강은 변화정도가 비슷하였다.극점도를 비교하면,Nb와 Ti를 동시에 첨가한강, Nb를 단독으로 첨가한 강 그리고 Ti를 단독으로 첨가한강 모두 냉간 압연한 상태에서는{112}<110>집합조직이 발달하였으며 어닐링처리한 후에는 {111}<112>집합조직이 잘 발달하였다. 그러나 세 종류의 강간에 집합조직의 차이는 별로 없었다. 결정립도와 관계가 깊은 경도에서는 결정립도가 가장 작은 Nb 및 Ti동시첨가강에서 경도가 가장 높고, Nb단독첨가강, Ti단독첨가강의 순서로 감소하는 경향을 보였다.

• 한국세라믹학회지
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• 제36권3호
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• pp.325-331
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• 1999

SrWO4가 첨가된 (Sr1-xBax)(Mg1/3Nb2/3)O3의 마이크로파 유전특성에 관하여 조사하였다. 관찰된 조성영역에서 Sr(Mg1/3Nb2/3)O3과 Ba(Mg1/3Nb2/3)O3은 (Sr1-xBax)(Mg1/3Nb2/3)O3고용체를 형성하고 SrWO4의 첨가는 고용체의 소결성을 향상시켜 소결온도 155$0^{\circ}C$에서 상대밀도 97% 이상을 얻었다. 소결한 시편의 EDS분석결과, SrWO4의 첨가량이 많은 시편에서 2차상이 존재하는 것을 알수 있었다. 순수한 Sr(Mg1/3Nb2/3)O3에 SrWO4를 0.01 mole첨가하여 1550~1$600^{\circ}C$에서 소결한 시편의 유전특성은 $\varepsilon$r 30, Q$\times$fo$\geq$55000,$ au$f -23 ppm/$^{\circ}C$이었다. 0.01 mole SrWO4가 첨가된 (Sr1-xBax)(Mg1/3Nb2/3)O3 고용체의 유전율과 온도계숙가 x에 따라 점차적으로 계속 증가하였고 Q$\times$fo는 x$\leq$0.25에서 x에 따라 감소하고 x$\geq$0.3에서 다시 증가하였다. (Sr0.65Ba0.35)(Mg1/3Nb2/3)O3+0.01SrWO4의 조성을 갖는 시편에서 $\varepsilon$r 34.4, Q$\times$fo$\geq$55000,$\tau$f 0 ppm/$^{\circ}C$이었다.

• Transactions on Electrical and Electronic Materials
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• 제12권2호
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• pp.72-75
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• 2011

In this study, $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3+0.9$ mol% $K_{5.4}Cu_{1.3}Ta_{10}O_{29}+x$ mol% $K_4CuNb_8O_{23}$ (x = 0, 0.2, 0.6, 0.8) ceramics were prepared by a conventional mixed oxide method. Their microstructure and electric properties were investigated. The secondary phase was made by virtue of $K_4CuNb_8O_{23}$ (KCN) addition in the $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3$ system ceramics. However, the sinterability of the ceramics increased with increasing $K_4CuNb_8O_{23}$ content. At the 0.6 mol% $K_4CuNb_8O_{23}$ added composition ceramics sintered at $1,060^{\circ}C$, kp and $d_{33}$ showed the optimum values of 0.39 and 145 pC/N, respectively, suitable for piezoelectric actuator application.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 춘계학술발표회 초록집
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• pp.45-52
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• 1995

광 촉매로 널리 알려진 TiO$_2$의 광 분해 거동의 변화를 관찰하기 위하여 Nb$_2$O$_{5}$를 첨가하여 sol-gel 용법으로 제조한 후 DCA(dichloroacetic acid) 의 광분해 효율을 측정하였다. Sol-gel process 과정에서 첨가된 Nb$_2$O$_{5}$의 농도 및 열처리 온도변화에 따른 광분해 효율을 관찰한 결과, Nb$_2$O$_{5}$를 첨가한 후 40$0^{\circ}C$에서 한시간 동안 열처리 한 광 촉매의 광분해 효율이 가장 높게 나타났다. 또한 열처리 온도와 무관하게 Nb$_2$O$_{5}$의 양이 증가할수록 광분해 효율은 감소하는 것으로 관찰되었다. 이는 excess electron 의 증가로 환원 반응 혹은 recombination rate기 증가하기 때문이라고 사료된다. 분해 대상 물질의 pH가 낮을수록 광분해 효율이 증가하는 것을 알 수 있었다.알 수 있었다.