• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.5
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• pp.517-524
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• 1992

In this study, 0.10Pb(SbS11/2TSnS11/2T)OS13T-(0.90-x)PbZrOS13T (0.25 x 0.40) ceramics were fabricated by the atmospheric method. The sintering temperature and time were 1250[$^{\circ}C$] and 2[2hr], respectively. The structureal, dielectric and piezoelectric properties with composition of PbTiOS13T were studied. As the results of XRD ans SEM, the crystal structure of a specimen was rhombohedral, lattice constant and average grain size were decreased with increasing the contents of PbTiOS13T. Relative dielectric constant and Curie temperature were increased with increasing the contents of PbTiOS13T, 0.10PSS-0.40PT-0.50PZ specimen had the highest values of 904 and 265[$^{\circ}C$], respectively. In increasing of PbTiOS13T contents form 25[mol%] to 40[mol%], piezoelectric charge constant and electromechanical coupling factors were increased form 114[pC/N] to 142[pC/N], 17[%] to 24[%] and mechanical quality factor were decreased with increasing the contents of PbTiOS13T. In the 0.10PSS-0.40PT-0.50PZ specimens, those values were 14.2[kV/cm] and 9.43[x10S0-6TC/cmS02T], resectively.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.321-324
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• 1991

In this study, $(Sr{\cdot}Pb)TiO_3$ series ceramics which is used in high voltage were fabricated by the mixed oxide method, and the electrical conduction mechanism and D.C. breakdown voltage characteristics of the specimens in accordance with the contents of $Bi_2O_3{\cdot}3TiO_2$ were investigated. As a result, the leakage current was increased with the contents of $Bi_2O_3{\cdot}3TiO_2$ and the measuring temperature. At room temperature, the leakeage current was showed a tendency of saturating when D.C. electrical field of $l5{\sim}30$[kV/cm] was applied to the specimen. As a result of breakdown voltage characteristics. breakdown strength was decreased when the contents of $Bi_2O_3{\cdot}3TiO_2$ were increased. On the other hand, in the temperature region below $60[^{\circ}C]$, the electronic breakdown was occured, and in the temperature region from 60 to $200[^{\circ}C]$, the thermal breakdown was occured by the Joule heat and the dissipation factor.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.383-386
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• 1998

The microwave dielectric properties and sintering properties of the xCaTi $O_{3}$-yMgTi $O_{3}$-z(L $i_{1}$2/N $d_{1}$2/)Ti $O_{3}$ systems were investigated for the development of microwave dielectric materials. Dielectric constants decreased with increasing the amounts of MgTi $O_{3}$ and increased with reducing the amounts of MgTi $O_{3}$ and increased with reducing (L $i_{1}$2/N $d_{1}$2/)Ti $O_{3}$ contents. The microscopic structures were mixed phase with a little second phase. We found some compositions with .tau.$_{f}$ changed from positive to negative value with increasing MgTi $O_{3}$ or (L $i_{1}$2/N $d_{1}$2/)Ti $O_{3}$ contents. The microscopic strucstures were mixed phase with a little second phase. We found some compositions with .tau.$_{f}$ =0ppm/.deg.C. these compmsitions exhibited the stable dielectric properties on the various sintering temperatures.res.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1095-1096
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• 2006

When $Y_2O_3$ was added to Ti-excess $BaTiO_3$ ((Ba+Y)/Ti =1), the area occupied by $Y^{3+}$ ion was confirmed by its microstructure development, electrical conductivity behavior and lattice constant. Grain growth inhibition was observed when the content of donor dopant exceeded a critical value ($x{\approx}.0.01$) in $BaTiO_3+x(0.5Y_2O_3+TiO_2)$ system. A donor-doped behavior was observed at various Y contents ($0.2\sim3.0$ mol% Y) when $Y_2O_3$ was added to $TiO_2$-excess $BaTiO_3$. As Y content was increased, (002) and (200) peaks shifted to higher angles and the lattice constant (a and c axis) decreased gradually.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.359-362
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• 1988

In this papers, in order to decreased the ZnO varistor breakdown voltage, additives the $TiO_2$ with ZnO varistors. The effects of addition $TiO_2$ with ZnO varistor are discussed. Observation of ZnO varistor microstructures are photospectroscopy and SEM, and variation of phase are XRD analysis. Experimental results, the more increased the $TiO_2$ contents the more decreased the mean grain size of ZnO. Also, results of XRD analysis, the more increased the $TiO_2$ contents the more increased the spinel structures.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.190-192
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• 1994

Microwave dielectric properties of $0.15(Ba_xSr_{0.05})O-0.15(Sm_{2(1-y)}Nd_{2y})O_3-0.7TiO_2$ ($x=0.9{\sim}1.0[mol.]$, y=6[m/0]) and $0.15(Ba_{0.95}Sr_{0.05})O-0.15(Sm_{2(1-y)}Nd_{2y})O_3-zTiO_2$(y=6[m/o], $z=0.66{\sim}0.7[mol.]$) ceramics were investigated with the contents of BaO and $TiO_2$. In the specimen with contents of BaO (0.975[mol.]), dielectric constant, quality factor and temperature coefficient of resonant frequency have good values of 76.52, 3001(at 3[GHz]), +0.71[ppm/$^{\circ}C$], respectively. In the specimen with contents of $TiO_2$(0.69[mol.]), dielectric constant, quality factor and temperature coefficient of resonant frequency showed the maximum values of 80.89, 3057(at 3[GHz]), +26.12[ppm/$^{\circ}C$], respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1097-1098
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• 2006

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. Silica coated $BaTiO_3$ powders were prepared by sol-gel method. The particle size of the $BaTiO_3$ powders were $\sim35$ nm and the thickness of the $SiO_2$ coating layer was $\sim5$ nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion. The Zeta potential of $SiO_2$ coated $BaTiO_3$ was getting close to that of pure silica with a more negative charge, compared with that of the uncoated $BaTiO_3$. The onset temperature of shrinkage curves shifted to higher temperatures with increasing $SiO_2$ contents

• Advances in materials Research
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• v.9 no.2
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• pp.99-107
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• 2020

Reinforced aluminum alloy base composites have become increasingly popular for engineering applications, since they usually possess several desirable properties. Recently, Warm Accumulative Roll Bonding (WARB) process has been used as a new novel process to fabricate particle reinforced metal matrix composites. In the present study, TiO₂ particles are used as reinforcement in aluminum metal matrix composites fabricated through warm accumulative roll bonding process. Firstly, the raw aluminum alloy 1060 strips with TiO₂ as reinforcement particle were roll bonded to four accumulative rolling cycles by preheating for 5 min at 300℃before each cycle. The mechanical and bonding properties of composites have been studied versus different volume contents of TiO₂ particles by tensile test, peeling test and vickers micro-hardness test. Moreover, the fracture surface and peeling surface of samples after the tensile test and peeling test have been studied versus different amount of TiO₂ volume contents by scanning electron microscopy. The results indicated that the strength and the average vickers micro-hardness of composites improved by increasing the volume content of TiO₂ particles and the amount of their elongation and bonding strength decreased significantly.

• Journal of the Korean institute of surface engineering
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• v.48 no.2
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• pp.43-49
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• 2015

This study reports a fabrication of $TiO_2$ on the surface of dental implants by pulsed d.c. magnetron sputtering from a Ti target. A systematic investigation on the microstructure and mechanical properties of $TiO_2$ films was carried out with the variation of $O_2$ contents and substrate temperatures. The effects of deposition parameters on the fabricated structures were investigated by X-ray diffraction (XRD) technique and field emission scanning electron microscope (FE-SEM). Hydrophilic properties were evaluated by measuring water contact angles on the film surface. With increasing $O_2$ contents up to 40%, surface roughness of $TiO_2$ film increased while relatively smooth surface was obtained with 50% $O_2$ contents. Surface roughness and adhesion strength both increased as substrate temperature increased up to $200^{\circ}C$. From these results, hydrophilic and adhesive properties of the present $TiO_2$ films synthesized with 40% $O_2$ at $200^{\circ}C$ are regarded to be suitable for bio-compatible applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1990.10a
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• pp.68-70
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• 1990

(1-X)(Sr$\_$7/9/Pb$\_$2/9/)$\_$(1-y)/(Ca$\_$1/5/Mg$\_$4/5/)$\_$y/TiO$_3$+X(BiO$_2$O$_3$$.$3TiO$_2$) (y=0.145, 0$\leq$X$\leq$0.08) ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 1180∼1230[$^{\circ}C$], 2[hr], respectly. The grain size were grown with increasing the contents of Bi$_2$O$_3$$.$3TiO$_2$, but decreased more and less in the specimens which had more than 0.04[mol].