• 한국세라믹학회지
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• 제37권1호
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• pp.96-101
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• 2000

Comparative studies on microstructure, and mechanical and anti-oxidation properties between TiN and Ti-Si-N films were performed. The Ti-Si-N films were deposited on high-speed steel and silicon wafer substrates by plasma-assisted chemcial vapor deposition(PACVD) technique. The Si addition to TiN film caused to change the microstructure such as grain size refinement, randomly multi-oriented microstructure, and nano-sized codeposition of silicon nitride in the TiN matrix. The Ti-Si-N film, contains Si content of ∼7 at.%, showed the micro-hardness value of ∼3400 HK, which was higher than the pure TiN film whose hardness was ∼1500HK. The Ti-Si(7 at.%)-N film also showed much improved anti-oxidation properties compared with those of the pure TiN film. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film was formed and retarded further oxidation of the nitridelayer. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film which was characterized by nano-sized precipitates of silicon nitride phase in the TiN matrix and randomly oriented grains.

• 한국세라믹학회지
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• 제37권4호
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• pp.345-353
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• 2000

Carbon nanofibers were prepared from the decomposition of various carbon-containing gases over pure Ni, pure Fe and their alloys with Cu. They yields, properties, and structure of carbon nanofibers obtained from the various reaction conditions were analyzed. Type of reacting gas, reaction temperature and catalyst composition were changed as the reaction variable. With Ni-Cu catalysts, the maximum yields of carbon nanofibers were obtained at temperatures between 550 and 650$^{\circ}C$ according to the reacting gas mixtures of C2H2-H2, C2H4-H2 and C3H8-H2, and the surface areas of the carbon nanofibers produced were 20∼350㎡/g. In the case of CO-H2 mixture, the rapid deposition of carbon nanofibers occurred with Fe-Cu catalyst and the maximum yield were obtained around 550$^{\circ}C$ with the range of surface areas of 140∼170㎡/g. The electrical resistivity of carbon nanofiber regarded as the key property of filler for the application of electromagnetic interference shielding was very sensitive to the type of reactant gas and the catalyst composition ranging 0.07∼1.5Ωcm at a pressure of 10000 psi, and the resistivity of carbon nanofibers produced over pure nickel catalyst were lower than those over alloy catalysts. SEM observation showed that the carbon nanofibers produced had the diameters ranging 20∼300 nm and the straight structure of carbon nanofibers changed into the twisted or helical conformation by the variation of reacting gas and catalyst composition.

• 한국세라믹학회지
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• 제20권2호
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• pp.166-172
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• 1983

In this study the sillicon-alloyed isotropic pyrolytic carbon was deposited in the tumbling bed from the pyrolysis of propane and silicon tetrachloride and investigated whether the silicon-alloyed isotropic pyrolytic carbon deposited in this study was usable as bionaterial or not. The silicon-allyed isotropic pyrolytic carbon was varied by controlling the process variables such as propane con-concentration and the argon flow rate flowing in to the silicon tetrachloride bubbler at a fixed reaction bed tempera-ture of 120$0^{\circ}C$ a rotation of reaction tube of 40 rpm a bed particle weight of 7.5 g and a total flow rate of 21/min; the propane concentration was varied from 10 to 70 and the argon flow rate flowing into the silicon tetrachloride bubble from 0 to 1000 cc/min. The results show that the silicon-alloyed isotropic pyrolytic carbon was obtained at all conditions investigated, . And then the alloyed silicon content is rangion from 7 to 14.5 wt%. The density and deposition rate of deposited silicon-alloyed isotropic carbon increased axxording to silicon content and propane concentration. And the apparent crystal-size(Lc) of pyrolytic carbon is not changed with silicon content. The density and apparant crystallite size are respec-tively in the range of 1.94 to 2.06 and 20 to 25$\AA$ It is shown that the silicon-alloyed isotropic pyrolytic carbon ob-tained in this experiment is usable as biomaterial.

• 한국세라믹학회지
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• 제52권5호
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• pp.304-307
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• 2015

To reduce the lateral conduction loss of thin-film-processed cathodes, the microstructure of the thin-film cathode is engineered to contain a denser bridging layer in the middle. By doing so, the characteristic crack-like pores that separate the cathode domains in thin-film-processed cathodes and hamper lateral conduction are better connected and, as a result, the sheet resistance of the cathode is effectively reduced by a factor of 5. This induces suppression of the lateral conduction loss and expansion of the effective current collecting area; the cell performance is improved by more than 30%.

• 한국세라믹학회지
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• 제49권6호
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• pp.556-560
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• 2012

Nanocrystalline CrN coatings were deposited by DC and ICP-assisted magnetron sputtering on Si (100) substrates. The influences of the ICP power on the microstructural and crystallographic properties of the coatings were investigated. For the generation of the ICP, radio frequency was applied using a dielectric-encapsulated coil antenna installed inside the deposition chamber. As the ICP power increased from 0 to 500W, the crystalline grain size decreased. It is believed that the decrease in the crystal grain size at higher ICP powers is due to resputtering of the coatings as a result of ion bombardment as well as film densification. The preferential orientation of CrN coatings changed from (111) to (200) with an increase in the ICP power. The ICP magnetron sputtering CrN coatings showed excellent surface roughness compared to the DC magnetron sputtering coatings.

• 한국세라믹학회지
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• 제49권6호
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• pp.642-647
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• 2012

$TiO_2$ thin films for a pulse power capacitor were deposited by RF magnetron sputtering. The effects of the deposition gas ratio and thickness on the crystallization and electrical properties of the $TiO_2$ films were investigated. The crystal structure of $TiO_2$ films deposited on Si substrates at room temperature changed to the anatase from the rutile phase with an increase in the oxygen partial pressure. Also, the crystallinity of the $TiO_2$ films was enhanced with an increase in the thickness of the films. However, $TiO_2$ films deposited on a PET substrate showed an amorphous structure, unlike those deposited on a Si substrate. An X-ray photoelectron spectroscopy(XPS) analysis revealed the formation of chemically stable $TiO_2$ films. The dielectric constant of the $TiO_2$ films as a function of the frequency was significantly changed with the thickness of the films. The films showed a dielectric constant of 100~110 at 1 kHz. However, the dissipation factors of the films were relatively high. Films with a thickness of about 1000nm showed a breakdown strength that exceeded 1000 kV/cm.

• 한국세라믹학회지
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• 제48권5호
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• pp.335-341
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• 2011

Continuous SiC fiber-reinforced SiC-matrix composites ($SiC_f$/SiC) had been fabricated by electrophoretic infiltration combined with ultrasonication. Nano-sized ${\beta}$-SiC added with 12 wt% of $Al_2O_3-Y_2O_3$ additive and Tyranno$^{TM}$-SA3 fabric were used as a matrix phase and fiber reinforcement, respectively. After hot pressing at 5 different conditions, the density, microstructure and mechanical properties of $SiC_f$/SiC were characterized. Hot pressing at relatively severe conditions, such as $1750^{\circ}C$ for 1 and 2 h, resulted in a brittle fracture behavior due to the strong fiber-matrix interface in spite of their high flexural strength. On the other hand, toughened $SiC_f$/SiC composite could be achieved by hot pressing at milder condition because of the formation of weak interface in spite of the decreased flexural strength. These results proposed the importance of weak fiber-matrix interface in the fabrication of ductile $SiC_f$/SiC composite.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.445-449
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• 2018

Chromium plating is a common surface treatment technique extensively applied in industry due its excellent properties which include substantial hardness, abrasion resistance, corrosion resistance, surface color, and luster. In this study, the effect of $MoS_2$ particles of the composite coating was investigated. To improve the lubrication of mold, $Cr-P-C/MoS_2$ composite plating was studied by varying the $MoS_2$ content. The current efficiency of the composite plating incorporated $MoS_2$ particles was increased at $MoS_2$ contents of 0.5 and 1.0 g/l due to the incorporation of fine particles. On the other hand, when the content of $MoS_2$ is 1.0 g/l or more, the current efficiency is lowered due to an increase in impact on the cathode surface. In order to evaluate the mechanical properties of Scratch test were conducted. Scratch test confirmed the lubricity and abrasion resistance characteristics revealed that the composite plating with added $MoS_2$ had relatively low surface roughness and uniform surface modification to improve its properties.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.479-482
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• 2018

Polystyrene superstructure films show faint rainbow color, and this low color saturation limits its wide application. In this paper, polystyrene superstructure films with single bright blue color were prepared by vertical deposition self-assembly method using polystyrene microspheres with average diameter of $310{\pm}10nm$ as raw material. Polystyrene superstructure films were modified by adding nano-carbon powder, and effect of the amount of nano-carbon powde on color performance was studied. The results showed that without addition of nano-carbon powder, the superstructure films showed a faint rainbow color, while with addition of nano-carbon power, the superstructure films exhibited a single bright blue under the same natural light source. Changing the amount of nano-carbon powder addition could adjust color saturation of the film. With increasing the amount of nano-carbon powder addition from 0.008 wt% to 0.01 wt%, color saturation of the superstructure film increased gradually. Further increasing the amount of nano-carbon powder addition to 0.011wt%, color saturation of the superstructure film didn't increase anymore and tended to get dark.

• 센서학회지
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• 제31권4호
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• pp.255-259
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• 2022

In this study, we fabricated ZnS substrates with excellent transmittance in the mid-infrared region (3-5 ㎛) using hot pressing instead of conventional chemical vapor deposition (CVD). Diamond-like carbon (DLC) was coated on either one or both sides of the ZnS substrates to improve their mechanical properties and transmittance efficiency. To reduce the reflectance and further improve transmittance in the mid-infrared region, anti-reflection (AR) coating was designed for DLC/ZnS /AR and AR/ ZnS /AR structures. The coating structure, microstructure, and optical properties of the AR-coated ZnS substrates were subsequently investigated by employing energy dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared (FTIR) spectroscopy. The FTIR spectroscopy results demonstrated that, in the mid-infrared region, the average transmittance of the samples with AR coating on one and both sides increased by approximately 18% and 27%, respectively. Thus, AR coating improved the transmittance of the ZnS substrates.