• Membrane Journal
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• v.17 no.3
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• pp.254-268
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• 2007

Sodium type faujasite(FAU) zeolite layers with diverse materials characteristics(Si/Al ratio, thickness, and structural discontinuity) were hydrothermally grown on a porous $\alpha-Al_2O_3$ tube, and then the $CO_2/N_2$ separation was evaluated at $30^{\circ}C$ for an equimolar mixture of $CO_2$ and $N_2$. Among hydrothermal conditions, $SiO_2$ content in hydrothermal solution seriously affected materials characteristics: with an increment in the $SiO_2$ content, Si/Al ratio, thickness, and structural discontinuity of grown FAU zeolite layer simultaneously increased. The present study reveals that structural discontinuity(intercrystalline voids due to an incomplete densification and cracks induced by GIS Na-P1 phase) is the most important variable affecting the $CO_2/N_2$ separation. Also, it was suggested that the $CO_2$ desorption in permeate side be the rate-determining(slowest) step in the overall $CO_2$ permeation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.128-129
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• 2007

Cr-Al-N, Cr-Si-N 그리고 Cr-Al-Si-N 코팅막을 WC-Co 모재위에 AIP법과 DC 마그네트론 스퍼터링 법을 결합한 하이브리드 시스템을 이용하여 합성하였으며, Si함량에 따른 Cr-Al-Si-N 코팅막의 미세구조, 기계적 특성과 마찰 거동에 관해 비교 연구하였다. Cr-Si-N(${\sim}35GPa$)과 Cr-Al-Si-N(${\sim}55GPa$) 코팅막의 경도값은 CrN(${\sim}23GPa$)과 Cr-Al-N(${\sim}25GPa$) 코팅막과 비교하여 각각 증가하였고, CrN(${\sim}0.50$)과 Cr-Al-N(${\sim}0.84$)의 평균 마찰계수는 Si 함량이 9 at.% 일때, Cr-Si-N(${\sim}0.30$)과 Cr-Al-Si-N(${\sim}0.57$)으로 각각 감소하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.826-831
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• 2009

In this paper, a high power RF amplifier module using AlN substrate of high thermal conductivity has been proposed. This RF amplifier module has the advantage of compact size and effective heat dissipation for the packaging of high power chip. To fabricate the thru-hole and scribing line on AlN substrate, the key parameters of $CO_2$ laser were experimented. And then, microstrip lines and spiral planar inductors were fabricated on an AlN substrate using the thin-film process. The fabricated microstrip lines on the AlN substrate has an attenuation value of 0.1 dB/mm up to 10 GHz. The fabricated spiral planar inductor has a high quality factor, a maximum of about 62 at 1 GHz for a 5.65 nH inductor. Packaging of a RF power amplifier was implemented on an AlN substrate with thru-hole. From the measured results, the gain is 24 dB from 13 to 15 GHz and the output power is 33.65 dBm(2.3 W).

• Journal of the Korean institute of surface engineering
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• v.36 no.2
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• pp.109-115
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• 2003

Quaternary Ti-Al-Si-N films were deposited on WC-Co substrates by a hybrid deposition system of arc ion plating (AIP) method for Ti-Al source and DC magnetron sputtering technique for Si incorporation. The synthesized Ti-Al-Si-N films were revealed to be composites of solid-solution (Ti, Al, Si)N crystallites and amorphous Si3N4 by instrumental analyses. The Si addition in Ti-Al-N films affected the refinement and uniform distribution of crystallites by percolation phenomenon of amorphous silicon nitride, similarly to Si effect in TiN film. As the Si content increased up to about 9 at.%, the hardness of Ti-Al-N film steeply increased from 30 GPa to about 50 GPa. The highest microhardness value (~50 GPa) was obtained from the Ti-Al-Si-N film haying the Si content of 9 at.%, the microstructure of which was characterized by a nanocomposite of nc-(Ti,Al,Si) N/a$-Si_3$$N_4$.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.89-94
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• 2003

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high speed machining. New superhard Ti-Al-Si-W films, characterized by a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous $Si_3 N_4$ matrix, could be successfully synthesized on WC-Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ~50 GPa at the Si content of 9 at.%, respectively. And the X-ray diffraction patterns of Ti-Al-Si-N films with various Si content is investigated. In this study, Ti-Al-Si-N coatings were applied to end-mill tools made of WC-Co material by a hybrid coating system. Cutting tests fir the high-hardened material (STD11,$H_R$)C62 and their performances in high speed cutting conditions were studied. Also, the tool wear and tool lift of Ti-Al-Si-N with various si(6, 9, 19) contents were measured.

• Clean Technology
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• v.17 no.2
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• pp.166-174
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• 2011

The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $H_2$/CO-temperature programmed reduction ($H_2$/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of $T_{50%}$ was shifted ca. $30^{\circ}C$ to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of $CO_2$ on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated $Al^{3+}$ sites obtained through $^{27}Al$ NMR analysis is well correlated the catalytic performance.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.732-736
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• 2013

AlN epilayers were grown on a c-plane sapphire substrate using hydride vapor phase epitaxy (HVPE). A series of AlN epilayers were grown at $1120^{\circ}C$ with V/III ratios 1.5, 2.5 and 3.5, and the influence of V/III ratio on their properties was investigated. As the V/III ratio was increased, the surface roughness (RMS roughness), Raman shift of $E_2$ high peaks and full-width at half-maximum (FWHM) of symmetrical (002) & asymmetrical (102) of the AlN epilayers increased. However, the intensities of the Raman $E_2$ high peaks were reduced. This indicates that the crystal quality of the grown AlN epilayers was degraded by activation of the parasitic reaction as the V/III ratio was increased. Smooth surface, stress free and high crystal quality AlN epilayers were obtained at the V/III ratio of 1.5. The crystal quality of AlNepilayers is worsened by the promotion of three-dimensional (3D) growth mode when the flow of $NH_3$ is high.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.2
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• pp.77-81
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• 2011

Aluminum nitride (AlN) thin films were prepared by using nitrogen ion beam assisted reactive radio frequency (RF) magnetron sputtering on the glass substrates without intentional substrate heating. After deposition, the effect of nitrogen ion beam energy on the structural and optical properties of AlN films were investigated by x-ray diffraction (XRD), atomic force microscope (AFM) and UV-Vis. spectrophotometer, respectively. AlN films deposited with $N^+$ ion irradiation at 100 eV show the higher (002) peak intensity in XRD pattern than other films. It means that $N^+$ ion energy of 100 eV is the favorable condition for low temperature crystallization. AFM images also show that surface average roughness is increased from 1.5 to 9.6 nm with $N^+$ ion energy in this study. In an optical observation, AlN films which deposited by $N^+$ ion beam energy of 100 eV show the higher transmittance than that of the films prepared with the other $N^+$ ion beam conditions.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.658-659
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• 2006

Magnetron sputtered TiN, (Ti, Al)N and TiN/(Ti, Al)N multilayer coatings grown on cemented carbide substrates have been characterized by using electron probe microanalysis (EPMA), X-ray diffraction (XRD), scanning electron spectroscopy (SEM), nanoindentation, scratcher and cutting tests. Results show that TiN coating is bell mouth columnar structures, (Ti, Al)N coating is straight columnar structures and the modulation structure has been formed in the TiN/(Ti, Al)N multilayer coating. TiN/(Ti, Al)N multilayer coating exhibited higher hardness, better adhesion with substrate and excellent cutting performance compared with TiN and (Ti, Al)N coating.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.368-372
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• 2011

Aluminum nitride (AlN) has excellent thermal conductivity, whereas it has some disadvantage such as low sinterability. In this study, the effects of sintering additive content and sintering condition on thermal conductivity of pressureless sintered AlN ceramics were examined on the variables of 1~3 wt% sintering additive ($Y_2O_3$) content at $1900^{\circ}C$ in $N_2$ atmosphere with holding time of 2~10 h. All AlN specimens showed higher thermal conductivity as the $Y_2O_3$ content and holding time increase. The formation of secondary phases (yttrium aluminates) by reaction of $Y_2O_3$ and $Al_2O_3$ from AlN surface promoted the thermal conductivity of AlN specimens, because the secondary phases could reduce the oxygen contents in AlN lattice. Also, thermal conductivity was increased by long sintering time because of the uniform distribution and the elimination of the secondary phases at the grain boundary by the evaporation effect during long holding time. A carbothermal reduction reaction was also affected on the thermal conductivity. The thermal conductivity of AlN specimens sintered at $1900^{\circ}C$ for 10 h showed 130~200W/mK according to the content of sintering additive.