• Journal of the Korean Ceramic Society
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• v.45 no.10
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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.

• Journal of Technologic Dentistry
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• v.27 no.1
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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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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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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• v.29 no.3
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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}$.

• Korean Journal of Materials Research
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• v.25 no.7
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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.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.2
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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.

• Korean Journal of Materials Research
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• v.3 no.1
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• pp.43-49
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• 1993

Excellent deep drawability and strain aging rsistance are obtained by the addition of alloying elements such as Ti and Nb which can form carbide and nitride easily into Al killed extra low carbon steel. Recrystallization textures and mechanical properties of the three different extra low carbon steels with B containing Nb only, Ti only, and both Nb and Ti, respectively, along with have been compared. Inverse pole figure shows that (100) and (111) texture intensities of Nb containing steel changed a lot during the annealing treatment and the degree of texture-structural change in the steel containing both Nb and Ti is about the same as that in the Ti-containing 5teel. After annealing the pole figure shows that the {Ill} < 110 > and {112} < 110> textures are the strongest in the cold rolled state and the annealed state, respectively. However, there is little difference in texture structure among the three kinds of steels. There is a tendency that the steel containing both Nb and Ti the grain size of which is the smallest is the highest in hardness. Nb-containing steel is the next and Ti -containing steel is the last in hardness.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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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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• v.12 no.2
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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.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.45-52
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• 1995

The photocatalytic activity of TiO$_2$ was investigated as a function of added amount of Nb$_2$O$_{5}$, heat treatment temperature and the decomposition rate of 1 mM dichloroacetic acid(DCA). Mixed oxides of TiO$_2$ and Nb$_2$O$_{5}$ was prepared by the sol-gel process. The addition of Nb$_2$O$_{5}$ into TiO$_2$ has deleterious effect on the decomposition rate of DCA, which was decreased as the amount of Nb$_2$O$_{5}$ was increased. The excess electrons due to the doping of Nb$_2$O$_{5}$ into TiO$_2$ can promote the reduction process instead of oxidation or recombination rate with electron holes. The most efficient photocatalyst was the one heat treated at 40$0^{\circ}C$ for an hour as far as the heat treatment temperature is concerned. The lower the pH of the solution, the higher the quantum yield.tum yield.