• Journal of Korean Society of Steel Construction
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• v.28 no.5
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• pp.373-382
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• 2016

Painting or thermally sprayed metal coating is often used in corrosion protection of steel structures. In recently, duplex coating system which combines thermally sprayed metals with paint is selected as a new generic type of coatings on steel structures under the highly corrosive environments. In this study, the structural steel specimens were surface treated, thermally sprayed with zinc, zinc-15%aluminum alloy, aluminum and aluminum-5%magnesium alloy, and finally sealing or painted with acrylic urethane. And as a reference specimens, steel specimens were painted with acrylic urethane after surface treatment. Circular defects with 1.0, 3.0 and 5.0 mm in diameters and line defect with 2.0 mm width, which reach the steel substrate were created on all specimens. The specimens were exposed into an environmental testing chamber controlled by the ISO 20340, which is a laboratory cyclic accelerated exposure test condition of spraying/UV/low temperature, for up to 175 days. Based on the corrosion tests, corrosion deterioration from the initial defects were evaluated and weathering performance of the specimens are compared.

• 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.

• 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.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.451-458
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• 2002

플라즈마 용사법에 의한 섬유강화 복합 소재를 개발하면서 독특한 미세구조가 발견되었다. 이러한 형상은 코팅의 물리적 특성과 직접적으로 관련이 있다고 사료된다 섬유강화 코팅의 구조를 밝히기 위해 고배율 전자현미경이 사용되었으며 분석을 통해 일반적 용사코팅 의 미세구조가 내부에 투입된 강화 섬유(FIBER 또는 WHISKER)에 의해 변형되며 열적으로 anisotropic한 상태로 되었음을 보여주었다.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.97-108
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• 2016

Thermally sprayed metals or organic coatings is often used in corrosion protection of steel structures. Duplex coating systems of thermally sprayed metal in combination with organic coating are selected as a new generic type of coatings on steel structures under the highly corrosive environments. In this study, three types of corrosion tests were carried out on four types of thermal sprayed specimens with sealing: zinc, zinc-15%aluminum alloy, aluminum and aluminum-5%magnesium alloy, four types of duplex coated specimens; thermally sprayed metals in combination with paint of acrylic urethane, and painted specimens. NORSOK M-501, Wet/dry cyclic seawater tests and outdoor exposure tests of nine types of specimens were conducted. From the corrosion test results, weathering performance of them were presented.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.319-319
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• 2015

본 연구에서는 강재의 부식 방지를 목적으로 기존의 도장 방식법에 비해 내식성 및 내구성을 향상시키기 위해 아크 용사코팅법을 적용하였다. 실험은 실제 환경을 고려하여 캐비테이션 환경 하에서 다양한 전기화학적 실험을 동시에 병행하여 캐비테이션-부식 복합손상 거동을 분석하고자 하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06a
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• pp.72-82
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• 1995

본 연구에서는 고온 내마모 부품에 사용되는 지르코니아계 세라믹을 이용하여 spray drying법으로 알루미나의 첨가량을 변화시킨 지르코니아-알루미나 복합 분말을 사용하여 플라즈마 용사법에 의해 코팅을 얻었다. 얻어진 코팅의 고온에서의 마모, 마찰 특성의 변화를 살펴보고자 하였다. 마모, 마찰실험은 상온~180$^{\circ}$C까지 수행하였으며 마모전과 후의 변화를 XRD, TEM, SEM 등을 이용하여 관찰하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1035-1040
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• 2011

This research was performed on a microfilter made of a hybrid material (ceramic + metal) that was coated with ceramics on the metal-filter surface by using the thermal spray method. The ceramic powders used were $Al_2O_3+40TiO_2$ powder with a particle size of $20{\mu}m$ and $Al_2O_3$ (98%+)powder with a particle size of $45{\mu}m$. The metal filters were filter-grade $20{\mu}m$, $30{\mu}m$, and $50{\mu}m$ sintered metal powder filters (SIKA-R 20 IS, 30 IS, 50 IS; Sinter Metals Filters) and filter-grade $75{\mu}m$ sintered mesh filter with five layers. Ceramic-coated filters that were coated using the thermal spray method had a great influence on powder material, particle size, and coating thickness. However, these filters showed a fine performance when used as micro-filters.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.757-765
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• 1998

This study was performed to investigate the influence of fuel/oxygen ratio (F/O= 3.2, 3.0, 2.8) on the oxidation behavior of two kinds of (20wt%NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$, and 7wt%NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$) composite powder with different manufacturing method. The results show that the oxidation behavior between the 20wt% NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$ and 7wt% NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ coating was widely different. The surface morphology of the coating composed of 7wt% NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ was changed to porous with F/O ratio by the aggressive evolution of gas phases($\textrm{CO}_2$, CO and $\textrm{CrO}_3$) and the oxide cluster composed of Ni and Cr were grown after oxidation at $1000^{\circ}C$ for 50 hours. But the surface morphology of the coating composed of 20wt% NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$ was not changed to porous after oxidation at $1000^{\circ}C$ for 50 hours. Therefore, the reason for high oxidation rate is due to activation of $\textrm{Cr}_{3}\textrm{C}_{2}$ to oxidation by entrapped oxygen gases within coating layer, and to closely relate with the decomposition of $\textrm{Cr}_{3}\textrm{C}_{2}$ to $\textrm{Cr}_{7}\textrm{C}_{3}$ phase. Accordingly, On the evidence of these results, the study about the oxidation behavoir of the HVOF sprayed $\textrm{Cr}_{3}\textrm{C}_{2}$ coating depending on hydrogen flow rate must be done.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.116-116
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• 2013

(Ni-22Cr-10Al-1Y)와 ($ZrO_2-25CeO_2-2.5Y_2O_3$)로 구성되는 금속/세라믹 복합코팅을 대기용사(ASP; air plasma spay)으로 철 기판위에 1:3, 2:2, 3:1의 무게비로 혼합하여 제조하였다. 용사된 코팅은 금속이영지역과 세라믹잉여지역으로 구별되고, 용사중에 NiCrAlY중의 Al이 선택적으로 산화되어 Al2O3가 계면에 존재하였다. 복합코팅은 $NaCl-Na_2SO_4$ 용융염에서 $800{\sim}900^{\circ}C$, 50시간 동안 부식실험을 실시하였다. 부식생성물은 NiO, $Cr_2O_3$, ${\alpha}-Al_2O_3$가 생성되는데, 부식이 진행되면서 용해되었다. 용융염 부식이 진행되는 동안에 Cr, Al이 외방확산하였고, Na, Cl, S는 내부로 확산되었다. 시간 및 온도뿐만 아니라 금속의 양이 증가할수록 코팅의 내식성은 저하되었다.