• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.172.1-172
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• 2000

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.561-565
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• 2012

Due to their unique combination of properties, Si-based ceramics, such as silicon carbide (SiC), silicon nitride ($Si_3N_4$) and silicon oxide ($SiO_2$ as fused silica), have a range of industrial applications in fields such as the chemical industry, aluminum manufacturing, oil and gas production and solar cell production. For each materials group, examples of typical applications from various industry sectors are presented while taking into account the property fingerprint.

• Applied Microscopy
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• v.44 no.2
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• pp.79-82
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• 2014

Aluminum nitride (AlN) powder was easily synthesized by the direct nitridation of Al melt containing ~20 wt.% Mg catalyst and the nitriding behavior was investigated by thermodynamic calculation and through observations of electron microscopy and X-ray diffraction. The addition of Mg catalyst decreased the nitriding temperature below $1,000^{\circ}C$, which is comparable to the high nitriding temperature of $1,400^{\circ}C$ required in carbothermal method. It was caused by a significant increase of the solubility of nitrogen gas due to the increase of Mg catalyst in Al melt. The dissolved nitrogen gas met Mg catalyst and was transformed into metastable $Mg_3N_2$. Finally the metastable phase reacted with Al to AlN.

• Corrosion Science and Technology
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• v.22 no.4
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• pp.232-241
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• 2023

The mechanical properties of the hydrogen valve responsible for supplying and blocking hydrogen gas in a hydrogen fuel cell electric vehicle (FCEV) were researched. Mechanical properties by hydrogen embrittlement were investigated by coating chromium nitride (CrN) and titanium nitride (TiN) on aluminum alloy by arc ion plating method. The coating layer was deposited to a thickness of about 2 ㎛, and a slow strain rate test (SSRT) was conducted after hydrogen embrittlement to determine the hydrogen embrittlement resistance of the CrN and TiN coating layers. The CrN-coated specimen presented little decrease in mechanical properties until 12 hours of hydrogen charging due to its excellent resistance to hydrogen permeation. However, both the CrN and TiN-coated specimens exhibited deterioration in mechanical properties due to the peeling of the coating layer after 24 hours of hydrogen charging. The specimens coated at 350 ℃ presented a significant decrease in ultimate tensile strength due to abnormal grain growth.

• Journal of the Korean Ceramic Society
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• v.31 no.1
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• pp.79-87
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• 1994

Aluminum nitride was hydrolyzed in contact with water, evolving the reaction heat of 172 cal/g within 12 hours to form alumina trihydrates. At 4$0^{\circ}C$ >, amorphous alumina hydrate was easily produced by the spontaneous breaks of AlN particle at the beginning of the hydrolysis process, while bayerite was formed by the dissolution-recrystallization processes of amorphous alumina hydrate at the temperature between 4$0^{\circ}C$ and 6$0^{\circ}C$, and pseudo-boehmite was generated on the surface of AlN particle by the condensation process of the corresponding phase at 6$0^{\circ}C$ <. The longer the hydrolysis timje or the higher the value of pH in solution, the more the bayerite phase was produced. However, pseudo-boehmite was easily generated under the following favorable conditions; when the hydrolysis reaction occured rapidly at the beginning and when the absorption of OH radical on the surface of AlN particle was disturbed by ethyl alcohol in a solution. However, aluminum nitride was hardly hydrolyzed in a solution of pH 2.0.

• Korean Journal of Materials Research
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• v.25 no.3
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• pp.138-143
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• 2015

Aluminum nitride, a compound semiconductor, has a Wurtzite structure; good material properties such as high thermal conductivity, great electric conductivity, high dielectric breakdown strength, a wide energy band gap (6.2eV), a fast elastic wave speed; and excellent in thermal and chemical stability. Furthermore, the thermal expansion coefficient of the aluminum nitride is similar to those of Si and GaAs. Due to these characteristics, aluminum nitride can be applied to electric packaging components, dielectric materials, SAW (surface acoustic wave) devices, and photoelectric devices. In this study, we surveyed the crystallization and preferred orientation of AlN thin films with an X-ray diffractometer. To fabricate the AlN thin film, we used the magnetron sputtering method with $N_2$, NH3 and Ar. According to an increase in the partial pressures of $N_2$ and $NH_3$, Al was nitrified and deposited onto a substrate in a molecular form. When AlN was fabricated with $N_2$, it showed a c-axis orientation and tended toward a high orientation with an increase in the temperature. On the other hand, when AlN was fabricated with $NH_3$, it showed a-axis orientation. This result is coincident with the proposed mechanism. We fabricated AlN thin films with an a-axis orientation by controlling the sputtering electric power, $NH_3$ pressure, deposition speed, and substrate temperature. According to the proposed mechanism, we also fabricated AlN thin films which demonstrated high a-axis and c-axis orientations.

• Composites Research
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• v.36 no.2
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• pp.101-107
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• 2023

In this study, aluminum nitride (AlN) reinforced aluminum (Al) matrix composites are fabricated via plasma arc melting under a nitrogen atmosphere. Within a minute of the chemical reaction between Al and N, dispersed AlN with the shape of transient and lamellar layers is in situ formed in the Al matrix. The composite contains 10 vol.% AlN reinforcements with low thermal resistance and strong bonding at the interfaces, which leads to the unique combination of thermal expansivity and conductivity in the resulting composites. The coefficient of thermal expansion of the composite can be further reduced when Si was alloyed into the Al matrix, which proposes the potential of the in situ Al matrix composites for thermal management applications.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.961-968
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• 1996

The aluminum nitride was synthesized by the self-propagating high-temperature synthesis(SHS). The synthe-sis was used aluminum powder mixed with AlN powder as reactant and the control factors affected to synthesis were considered compact density pressure of reaction gas AlN diluent content and aluminum powder size. The SHS reaction conducted with a reactant containing 50% AlN diluent under 0.8MPa nitrogen gas pressure yielded a complete conversion of aluminum powder to AlN powders. The size and purity of AlN produced were found to be comparable with that of AlN produced by the carbothermal nitrogen method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.872-875
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• 2003

Carbon nitride($CN_x$) thin films were deposited on quartz substrates using reactive RF magnetron sputtering system at uarious deposition conditions and investigated dielectric characteristics. Samples for capacitance measurements were of the MIM(Metal-Insulator-Metal) type devices. Aluminum film electrodes were prepared by a vacuum thermal evaporation method before and after the deposition of carbon nitride films. Capacitances were measured by a FLUKE PM6306 RCL Meter at room temperature. Current-voltage(I-V) characteristics and resistivity were measured by a CATS CA-EDA semiconductor test and analyzer. The carbon nitride films showed ${\alpha}-C_3N_4$ and ${\beta}-C_3N_4$ etc. peaks through Raman and FTIR. Observed surface of film and side structure using SEM(Scanning Electron Microscope), and measured thickness of film by ${\alpha}-step$. We can find that the dielectric constant was the lowest value in 50% nitrogen ratio and the resistivity was the highest value in 70% nitrogen ratio.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.483-484
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• 2012