• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1034-1042
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• 1996

Various $TiO_2-SiO_2$ composite powders were prepared by the modified sol-gel method using 1-dodecanol as DCCA (Dryng Control Chemical Additive ). Their characterizations were carried out and their photocatalytic catalysis was examined on the evolution reaction of hydrogen. The weight losses at $500^{\circ}C$ of only $TiO_2$ and $SiO_2$ powders were 33. 0wt% and 42.5wt%, respectively, and those of the $TiO_2/SiO_2$ powders ($TiO_2/SiO_2=25/75$, 50/50 and 75/25) were about $70.0{\pm}3.0wt%$. The released substances from the powders were almost organic matters. The as-prepared powders except only $TiO_2$ powder were amorphous. Transformation of anatase to rutil was hindered by $SiO_2$ component and the crystallinity of anatase was decreased with increasing $SiO_2$ contents. The as-prepared powders were bulky states. By heating at $600^{\circ}C$ for 1 hr $TiO_2-SiO_2$ powders ($TiO_2=100%$, $TiO_2/SiO_2=75/25,\;50/50$) showed agglomerates consisted of particles in submicron, but those of $TiO_2/SiO_2=25/75$ and $SiO_2=100%$ were still bulky states. Specific surface area of the powders heat-treated at $600^{\circ}C$ for 1hr was increased with $SiO_2$ concents and their pore sizes were also depended on $SiO_2$ contents. The photocatalytic activity of $TiO_2/SiO_2=75/25$ heat-treated at $600^{\circ}C$ for 1hr was 0.240mo1/h.g-cat as $H_2$ evolution rate. This value was about 2.0 times that of P-25(Degussa P-25) as a standard photocatalyst.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.106-106
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• 2003

반도체 소자의 고집적화에 따라 채널길이와 배선선 폭은 점차 줄어들고, 이에 따라 단채널효과, 소스/드레인에서의 기생저항 증가 및 게이트에서의 RC 시간지연 증가 등의 문제가 야기되었다. 이를 해결하기 위하여 자기정렬 실리사이드화(SADS) 공정을 통해 TiSi2, CoSi2 같은 금속 실리사이드를 접촉 및 게이트 전극으로 사용하려는 노력이 진행되고 있다. 그런데 TiSi2는 면저항의 선폭의존성 때문에, 그리고 CoSi2는 실리사이드 형성시 과도한 Si소모로 인해 차세대 MOSFET소자에 적용하기에는 한계가 있다. 반면, NiSi는 이러한 문제점을 나타내지 않고 저온 공정이 가능한 재료이다. 그러나, NiSi는 실리사이드 형성시 NiSi/Si 계면의 산화와 거침성(roughness) 때문에 높은 누설 전류와 면저항값, 그리고 열적 불안정성을 나타낸다. 한편, 초고집적 소자의 배선재료로는 비저항이 낮고 electro- 및 stress-migration에 대한 저항성이 높은 Cu가 사용될 전망이다. 그러나, Cu는 Si, SiO2, 실리사이드로 확산·반응하여 소자의 열적, 전기적, 기계적 특성을 저하시킨다. 따라서 Cu를 배선재료로 사용하기 위해서는 확산방지막이 필요하며, 확산방지재료로는 Ti, TiN, Ta, TaN 등이 많이 연구되고 있다.

• Journal of the Korean Ceramic Society
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• v.54 no.4
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• pp.340-348
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• 2017

$SiC_f/SiC$ composites were joined using a $60{\mu}m-thick$ $Ti_3AlC_2$ or $Ti_3SiC_2$ MAX phase tape. The filler tape was inserted between the $SiC_f/SiC$ composites containing a 12 wt.% $Al_2O_3-Y_2O_3$ sintering additive. The joining was performed to a butt-joint configuration at $1600^{\circ}C$ or $1750^{\circ}C$ in an Ar atmosphere by applying 3.5 MPa using a hot press. Microstructural and phase analyses at the joining interface confirmed the decomposition of $Ti_3AlC_2$ and $Ti_3SiC_2$, indicating the joining by solid-state diffusion. The results showed sound joining interface without the presence of cracks. Joining strengths higher than 150 MPa could be obtained for the joints using $Ti_3AlC_2$ or $Ti_3SiC_2$ at $1750^{\circ}C$, while those for joined at $1600^{\circ}C$ decreased to 100 MPa approximately without the deformation of the joining bodies. The thickness of initial filler tape was reduced significantly after joining because of the decomposition and migration of MAX phase owing to the plasticity at high temperatures.

• Journal of Welding and Joining
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• v.14 no.4
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• pp.99-108
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• 1996

The microstructure and bond strength are examined on the SiC/SiC and SiC/mild steel joints brazed by the Ag-Ti based alloys with different Ti contents. In the SiC/SiC brazed joints, the thickness of the reaction layers at the bond interface and the Ti particles in the brazing alloy matrices increase with Ti contents. When Ti is added up to 9 at% in the brazing alloy. $Ti_3SiC_2$ phase in addition to TiC and $Ti_5Si_3$ phase is newly created at the bond interface and TiAg phase is produced from peritectic reaction in the brazing alloy matrix. In the SiC/mild steel joints brazed with different Ti contents, the microstructure at the bond interface and in the brazing alloy matrix near SiC varies similarly to the case of SiC/SiC brazed joints. But, in the brazing alloy matrix near the mild steel, Fe-Ti intermetallic compounds are produced and increased with Ti contents. The bond strengths of the SiC/SiC and SiC/mild steel brazed joints are independent on Ti contents in the brazing alloy. There are no large differences of the bond strength between SiC/SiC and SiC/mild steel brazed joints. In the SiC/mild steel brazed joints, Fe dissolved from the mild steel does not affect on the bond strength of the joints. Thermal contraction of the mild steel has nearly no effects on the bond strength due to the wide brazing gap of specimens used in the four-point bend test. The brazed joints has the average bond strength of about 200 MPa independently on Ti contents, Fe dissolution and joint type. Fracture in four-point bend test initiates at the interface between SiC and TiC reaction layer and propagates through SiC bulk. The adhesive strength between SiC and TiC reaction layer seems to mainly control the bond strength of the brazed joints.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1228-1229
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• 2008

The composites were fabricated 61[vol.%] ${\beta}$-SiC and 39[vol.%] $TiB_2$ powders with the liquid forming additives of 12[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid by pressure or pressureless annealing at 1,650[$^{\circ}C$] for 4 hours. Reactions between SiC and transition metal $TiB_2$ were not observed in the microstructure and the phase analysis of the SiC-$TiB_2$ electroconductive ceramic composites. Phase analysis of SiC-$TiB_2$ composites by XRD revealed mostly of ${\alpha}$-SiC(6H), $TiB_2$, and In Situ $YAG(Al_5Y_3O_{12})$. The relative density, the flexural strength and the Young's modulus showed the highest value of 88.32[%], 136.43[MPa] and 52.82[GPa] for pressure annealed SiC-$TiB_2$ composites at room temperature. The electrical resistivity showed the lowest value of 0.0162[${\Omega}{\cdot}cm$] for pressure annealed SiC-$TiB_2$ composite at 25[$^{\circ}C$]. The electrical resistivity of the pressure annealed SiC-$TiB_2$ composite was positive temperature coefficient resistance (PTCR) but the electrical resistivity of the pressureless annealed SiC-$TiB_2$ composites was negative temperature coefficient resistance(NTCR) in the temperature ranges from 25[$^{\circ}C$] to 700[$^{\circ}C$].

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3767-3771
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• 2012

In this study, we investigate the potential use of $TiO_2@SiO_2$ and $ZnO@SiO_2$ core/shell nanoparticles (NPs) as effective UV shielding agent. In the typical synthesis, $SiO_2$ was coated over different types of $TiO_2$ (anatase and rutile) and ZnO by sol-gel method. The synthesized $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs were characterized by UV-Vis, XRD, SEM and TEM. The UV-vis absorbance and transmittance spectra of core@shell NPs showed an efficient blocking effect in the UV region and more than 90% transmittance in the visible region. XRD and SAED studies confirmed the formation of amorphous $SiO_2$ coated over the $TiO_2$ and ZnO NPs. The FESEM and TEM images shows that coating of $SiO_2$ over the surface of anatase, rutile $TiO_2$ and ZnO NPs resulted in the increase in particle size by ~30 nm. In order to study the UV light shielding capability of the samples, photocatalytic degradation of methylene blue dye on $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs was performed. Photocatalytic activity for both types of $TiO_2$ NPs was partially suppressed. In comparison, the photocatalytic activity of ZnO almost vanished after the $SiO_2$ coating.

• Journal of Surface Science and Engineering
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• v.37 no.3
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• pp.152-157
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• 2004

Ti-Al-N ($Ti_{75}$ $Al_{25}$ N) and Ti-Al-Si-N ($Ti_{69}$ $Al_{23}$ $Si_{8}$N) coatings synthesized by a DC magnetron sputtering technique were studied comparatively with respect to phase characterization and high-temperature oxidation behavior. $Ti_{69}$ $Al_{23}$ $Si_{ 8}$N coating had a nanocomposite microstructure consisting of nanosized(Ti,Al,Si)N crystallites and amorphous $Si_3$$N_4$, with smooth surface morphology. Ti-Al-N coating of which surface $Al_2$$O_3$ layer formed during oxidation suppressed further oxidation. It was sufficiently stable against oxidation up to about $700^{\circ}C$. Ti-Al-Si-N coating showed better oxidation resistance because both surface Ab03 and near-surface $SiO_2$ layers suppressed further oxidation. XRD, GDOES, XPS, and scratch tests were performed.

• Journal of Surface Science and Engineering
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• v.42 no.2
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• pp.73-78
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• 2009

Quinary Ti-Al-Si-C-N films were successfully synthesized on SUS 304 substrates and Si wafers by a hybrid coating system combining an arc ion plating technique and a DC reactive magnetron sputtering technique. In this work, the effect of Si content on the microstructure and mechanical properties of Ti-Al-C-N films were systematically investigated. It was revealed that the microstructure of Ti-Al-Si-C-N coatings changed from a columnar to a nano-composite by the Si addition. Due to the nanocomposite microstructure of Ti-Al-Si-C-N coatings, the microhardness of The Ti-Al-Si-C-N coatings significantly increased up to 56 GPa. In addition the average friction coefficients of Ti-Al-Si-C-N coatings were remarkably decreased with Si addition. Therefore, Ti-Al-Si-C-N coatings can be applicable as next-generation hard-coating materials due to their improved hybrid mechanical properties.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.263-266
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• 2000

This paper is focused on the fabrication of reliable Al/$TiO_2-SiO_2$/Mo antifuse, which could operate at low voltage along with the improvement in on/off state properties. Mo metal as the bottom electrode had smooth surface and high melting point, and was being kept as-deposited $SiO_2$film stable. The breakdown voltage of TiO_2-SiO_2$ stacked antifuse was better than that of same-thickness (100 $\AA$) $SiO_2$antifuse because of Ti diffusion in $SiO_2$. The improving breakdown-voltage and on-resistance can be obtained as well as the influence of hillock in the bottom metal is reduced by using double insulator. Low on-resistance (65 $\Omega$) and low programming voltage (9.0 V) can be obtained in these antifuses with 250 $\AA$ double insulator.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.168-175
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• 1992

The surface and interface morphology as well as the sheet resistance, and uniformity of TiSiz film are significantly improved and the lateral titanium silicide growth over the oxide spacer is minimized by the use of ion beam mixing and rapid thermal annealing in nitrogen ambient. In addition, TiSiz film formations on TiISi and TiISiOz system were also studied.