• Journal of Welding and Joining
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• v.7 no.2
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• pp.25-34
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• 1989

The purpose of this work is to coat ZrO$_{2}$ - 8Y$_{2}$O$_{3}$ ceramic on the Al cast alloy(AC-8A) by using the plasma spray method. Two types of coatings which were composed of two and three layer coating were examined. Each coating powder was analyzed for shape and size distribution and X-ray diffraction pattern. For the coated layers, microstructural analysis and performance estimation which was composed of static thermal test, thermal cyclic test and thermal shock test were conducted.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.52-53
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• 2020

The thermal spray coating process is being used to protect the metals and alloys from wear, abrasion, fatigue, tribology, and corrosion failure. Therefore, in the present study, Al and Zn was deposited by plasma arc thermal spray process onto the steel substrate and their performance was assessed. The bond adhesion result shows that Al coating has higher value attributed to compact, dense, and less porous compared to Zn coating which contain defects/pores and uneven morphology assessed by scanning electron microscopy (SEM). Electrochemical results show that the Al coating exhibited higher impedance value compared to Zn in artificial ocean water solution at prolonged exposure periods. However, both coatings show the increment in polarization resistance with exposure periods which reveal that porosity of coatings is filled by the corrosion products.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1205-1210
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• 1999

Far infrared ceramic/aluminum composite powders for thermal spray were fabricated by spray drying method and investigated the characteristics of the plasma sprayed coating layers, I.e. microstructure, phases, thermal shock resistance and spectral emissivity. The shape of the spray dried composite powder was spherical and the particle size distribution was 34~105${\mu}m $. Aluminum was distributed homogeneously in the spray dried composite powder. Spectral emissivity of the plasma sprayed coating layer ranges from 3 to 14${\mu}m $ whereas spectral emissivity of the raw ceramic powder ranges from 8 to 14${\mu}m $. And then spectral emissivity of the coatings was better than that of the raw powder but spectral emissivity was decreased with increasing aluminum content. It was found that aluminum content ranging from 20 to 30wt% was suitable for fabricating far-infrared radiator by plasma spraying method.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.10a
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• pp.131-132
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• 2012

The vacuum plasma coating was performed to analysis the characteristic and find the optimum process conditions for the vacuum plasma spray coating. It was observed that the square shape of powder in case of carbide ceramics does not fluidize well compared to the round shape of powder in case of oxide ceramics so that the plasma spraying is not uniform. The analysis through SEM and EDS mapping shows that the coatings represent excellent structural features with strong resistance against oxidation and satisfied result with vacuum plasma coating.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.481-486
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• 2014

Environmental barrier coatings (EBCs) are used to protect SiC-based ceramics or composites from oxidation and corrosion due to reaction with oxygen and water vapour at high temperatures above $1000^{\circ}C$. Mullite ceramics have been studied for environmental barrier coatings for Si-based ceramics. More recently, rare earth silicate ceramics have been identified as more water vapour-resistant materials than mullite for environmental barrier coatings. In this study, we fabricate mullite and yttrium silicate ceramics by an atmospheric plasma spray coating method using spherical granules fabricated by spray drying. As a result, EBCs with thicknesses in the range of $200-300{\mu}m$ are successfully fabricated without any macroscopic cracks or interfacial delamination. Phase and microstructure analysis are conducted, and the basic mechanical properties, such as hardness and indentation load-displacement curves are evaluated.

• Korean Journal of Materials Research
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• v.24 no.7
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• pp.357-362
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• 2014

Thermal barrier coatings(TBCs) are being applied in many industrial fields such as thermal power generation, aviation and seasonal fields. $ZrO_2-Y_2O_3$(8%) thermal spray coating powders are commercially used as thermal-barrier coating materials to protect against oxidation and corrosion of heat-resistant alloys at elevated temperatures. Currently, $ZrO_2-Y_2O_3$(8%) thermal-spray powder is made using the industrial co-precipitation process, which is very complex and requires a lot of time. In this study, orthorhombic $ZrO_2$ and $Y_2O_3$ powders were fabricated by mechanical mixing, which is more economical than the co-precipitation process. A tetragonal, yttria-stabilized zirconia(YSZ) coating-layer was produced by plasma spraying, using orthorhombic $ZrO_2-Y_2O_3$(8%) powder. Our experimental results indicate that $ZrO_2-Y_2O_3$(8%) mixed powder can be used economically in industry because it is no longer necessary to make this powder by liquid and gas-phase methods.

• Journal of Powder Materials
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• v.30 no.5
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• pp.424-430
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• 2023

YAG phosphor powders were fabricated by the atmospheric plasma spraying method with the spray-dried spherical YAG precursor. The YAG precursor slurry for the spray drying process was prepared by the PVA solution chemical processing utilizing a domestic easy-sintered aluminum oxide (Al₂O₃) powder as a seed. The homogenous and viscous slurry resulted in dense granules, not hollow or porous particles. The synthesized phosphor powders demonstrated a stable YAG phase, and excellent fluorescence properties of approximately 115% compared with commercial YAG:Ce³⁺ powder. The microstructure of the phosphor powder had a perfect spherical shape and an average particle size of approx imately 30 ㎛. As a result of the PKG test of the YAG phosphor powder, the synthesized phosphor powders exhibited an outstanding luminous intensity, and a peak wavelength was observed at 531 nm.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.460-467
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• 2003

Al-SiC$_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis.

• Tribology and Lubricants
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• v.19 no.5
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.65-70
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• 1998

The Spray-ICP technique uses the ICP(Inductively Coupled Plasma) of ultra-high temperature which is produced by r.f power. The ICP is well-kwown as a clean heat source for the preparation of pure ceramic particles because the ICP is a electrodeless-thermal plasma without contamination. In this study,{{{{ { SnO}_{2 } }}}} particles were sythesized from metal salt solution by Spray-ICP technique. The effects of concentration of solution, collecting location of powders were investicated. The prepared {{{{ { SnO}_{2 } }}}} particles from each concentration of solution had same crystalline phase(tetragonal {{{{ { SnO}_{2 } }}}}) a nd the mean size decreased in proportion to the increase of solution concentration. Each {{{{ { SnO}_{2 } }}}} p owders collector in reactor and electrostatic collector had same crystalline phase and morphologies. The mean size of {{{{ { SnO}_{2 } }}}} p articles prepared by Spray-ICP technique was below 30nm.