• 한국정밀공학회지
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• 제32권2호
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• pp.159-166
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• 2015

Slot-die coating is well known technique to guarantee a uniformly coated layer and is compatible with roll-to-roll process. In actual roll-to-roll slot-die coating process, the lateral difference of coated layer thickness is observed. An experimental study was performed to improve the coating quality. Coating speed and coating gap were selected as the experimental factors. A full factorial, statistical method was conducted to optimize the process conditions. Based on the results of repeated experiment, the lowest deviation of lateral thickness (700 nm, <10%) was achieved at 10 m/min coating speed and $300{\mu}m$ coating gap. This result has significance because such optimized process guideline can be utilized with all process improvement in various coating applications.

• 한국표면공학회지
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• 제32권6호
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• pp.709-716
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• 1999

Ceramic is select for an alternative substrate material for high-speed circuits due to its low-thermal expansion. As, in this study, ceramic was prepared by ISG (interlayer sol-gel) process using metal salts and a metal alkoxide as the starting materials. Generally ceramic substrate is used electroless copper plating for the metallization. But it has been indicate weakely the adhesion strength between the substrate and copper layer. Therefore, this research, using the ISG process on the preparation of homogeneous and possible preparation at law temperature fabricated sol solution. Using of the dip coating method was coated for the purpose of giving the anchoring effect on the coating layer and enhancing the adhesion strength between the $Al_2$O$_3$ substrate and copper layer. This study examined primary the characteristic of the sol making condition and differential thermal analysis (DTA) X-ray diffraction (XRD) were mearsured to identify the crystal phase of heat treatment specimens. The morphology of the coated films were studied by scanning electron microscopy(SEM). As a resurt, XRD analysis was obtained patterns of $\alpha$-cordierite after heat-treatment about 2 hours at $1000^{\circ}C$. SEM analysis could have seen a large number of voids on coated film. The more contants of$ Al_2$$O_3$ Wt% was increased the more voids was advanced. Peel adhesion strength has a maximum in the contants of the TEOS:ANE of 1:0.7 mole%. In this case, adhesion strength has been measured 1150gf, peel adhesion strength were about 10 times more than uncoated of the ceramics film.

• 한국생산제조학회지
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• 제18권6호
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• pp.629-635
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• 2009

In this research, KP-4, one of the plastic mold steels, was coated with the AlTiN from one layer to four layers by the PVD method in the $\Phi$ 8mm cemented carbide ball end mill. Coated KP-4 was processed with various conditions. For example, slope of $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ the spindle rotation speed was changed from 10,000rpm to 16,000rpm, the tool feeding speed was changed from 1,300mm/min to 1,700mm/min, the depth of cut was also changed from 0.3mm to 0.9mm, and etc. Cutting component force according to the coating layer number, and surface roughness were studied. The cutting component force showed a good agreement better the up ward direction than the down ward direction under all experimental conditions. In case of the condition per the material shape, it was lessen when the tool have larger angle because the average effective diameter of the tool is larger. The surface roughness showed good condition in case of the up ward than the down ward direction. And, in the 3rd layer of AlTiN coating, it showed the most suitable condition.

• 열처리공학회지
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• 제8권1호
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• pp.44-52
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• 1995

The specimen for laser hardening have been carried out using SM45C which is coated with black paint or graphite for better absorption. Segmented mirror was used in order to produce a square beam ($10{\times}10mm$) at the surface with a homegeneous intensity distribution across the beam. $CO_2$-Laser power was changed from 2kW to 4kW and transfer velocity was varied from 0.1m/min to 2.0m/min. The maximum hardness and case depth of SM45C steel are 790Hv and 1.5mm by laser hardening. When the surface of specimens was melted during laser hardening. the surface hardness of SM45C steel was decreased. The surface hardness of 2 layer coated specimen(black paint: $15.4{\mu}m$, graphite coating: $9.5{\mu}m$) was increased than that of 1 layer coated specimen. It is desirable to prepare 2 or more coating layer on the steel surface in order to sufficient case depth and hardness in laser hardening. The graphite coating on the specimen surface was obtained more uniform temperature distribution than black paint coating in laser hardening process.

• 한국초전도ㆍ저온공학회논문지
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• 제23권4호
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• pp.10-13
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• 2021

Recently, cable conductors composed of numerous coated conductors have been developed to transport huge current for large-scale applications, for example accelerators and fusion reactors. Various cable conductors such as CORC (Conductor on round core), Roebel Cable, and TSTC (Twisted stacked tape cable) have been designed and tested to apply for large-scale applications. But, these cable conductors cannot improve the engineering critical current density (J_e) because they are made by simple stacking of coated conductors. In this study, multi-HTS (High temperature superconductor) layers on one substrate (MHOS) wire was fabricated to increase the engineering critical current density by using the exfoliation of superconducting layer from substrate and silver diffusion bonding method. By the repetition of these processes, the 10 m long 6-layer MHOS conductor was successfully fabricated without any intermediate layers like buffer or solder. 6-layer MHOS conductor exhibited a high critical current of 2,460A/12mm-w. and high engineering critical current density of 1,367A/mm² at liquid nitrogen temperature.

• 한국표면공학회지
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• 제54권4호
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• pp.171-177
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• 2021

This paper is concerned with the surface hardness measurement of NiP-coated AA7050 using different loads from 10 to 100 g. The surface hardness was observed to increase from 180 to 600 H_v with increasing NiP layer thickness, depending on the load applied for indentation. When NiP coating thickness is thinner than 2 ㎛, the surface hardness of NiP-coated AA7050 was mainly determined by AA7050 substrate, while it was significantly increased by NiP coating layer when NiP coating thickness is thicker than 2 ㎛. Hardness of AA7050 substrate itself was not dependent on the applied load but the hardness of NiP-coated AA7050 was largely influenced by the load applied for indentation. The largest difference of hardness between 10 g and 100g of applied loads, was obtained at the NiP thickness of about 8 ㎛ above which the measured hardness at 10 g reached a maximum value of about 600 H_v. It was also observed that indentation-induced plastic deformation next to the indented zone occurs when NiP layer is 5.64 times thicker than the depth of impression formed by indentation.

• Corrosion Science and Technology
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• 제21권1호
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• pp.68-76
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• 2022

Several technologies are employed to protect substrates from corrosion and erosion damage. In particular, arc thermal spray coating technology is widely used as anti-corrosive technology for steel and concrete structures and is applied to offshore plants and petrochemical and drilling facilities. In this investigation, solid particle impingement erosion experiments were performed on an arc thermal spraying-coated specimen using 85% Al-14% Zn-1% Zr wire rod in KR-RA steel. This study investigated the effect of fluorosilicone sealing on the erosion resistance characteristics of the thermal spray coating layer. The erosion rates of the thermal spray-coated and sealed specimens were 4.1×10^-4 and 8.5×10^-4, respectively. At the beginning of the experiment, the fluorosilicone sealant was almost destroyed by the impact of the solid particles. The destruction time for the coating layer was 10 minutes for the thermal spray-coated specimen and 13 minutes for the sealed specimens, indicating that the sealed specimens had better erosion resistance characteristics to solid particle impingement.

• Tribology and Lubricants
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• 제34권2호
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• pp.67-73
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• 2018

Ni-Al intermetallic coating technology is an available method for the strengthening of aluminum substrate. In this study, Ni-Al intermetallics were coated on an aluminum substrate through a reaction synthesis process at a temperature lower than melting point of aluminum. And the sliding wear properties of the coatings have been investigated to verify their usability and compared the wear properties with those of a cast Al-12.5%Si alloy and an anodizing layer on aluminum. Results show that the wear rate of the coating layer greatly increased at 1 m/s and 1.5 m/s when compared with that of the cast Al-12.5%Si alloy. Much pitting damages were observed on the worn surfaces at these sliding speeds, unlike at other sliding speeds. The wear of the intermetallic coating layer at these sliding speeds seems to be increased by pitting as a consequence of adhesion. In contrast, wear of the coating layer at other speeds hardly occurs, regardless of wear periods. Nevertheless, the wear properties of the intermetallic coating layer on the aluminum substrate through the reaction synthesis process are more stable than those of anodized aluminum and are superior to those of the cast Al-12.5%Si alloy in a steady-state wear period.

• 한국광학회지
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• 제24권5호
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• pp.271-278
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• 2013

다층박막이 있는 기층에 단축이방성 배향막이 코팅되어 있을 때 비스듬히 입사한 빛의 유효반사계수 표현들을 유도하였다. 유효반사계수들과 타원상수들을 다층박막의 미지상수들은 물론 단축이방성 배향막의 광학이방성의 크기와 광축의 방향 그리고 배향막의 두께로 표현하였다. 이를 바탕으로 배향막의 정상굴절률과 이상굴절률, 배향된 두께 그리고 광축의 방위각과 기울임각을 다층박막의 두께나 조성비 등과 함께 타원법이 가지고 있는 높은 수준의 측정 정밀도를 유지하며 기존의 모델링 분석방법으로 결정할 수 있도록 하였다.

• 한국재료학회지
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• 제26권3호
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• pp.160-165
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• 2016

To increase the capacitance of an Al electrolytic capacitor, the anodic oxide film, $Al_2O_3$, was partly replaced by an $Al_2O_3-ZrO_2$ (Al-Zr) composite film prepared by the vacuum infiltration method and anodization. The microstructure and composition of the prepared samples were investigated by scanning electron microscopy and transmission electron microscopy. The coated and anodized samples showed multi-layer structures, which consisted of an inner Al hydrate layer, a middle Al-Zr composite layer, and an outer $Al_2O_3$ layer. The thickness of the coating layer could go up to 220 nm when the etched Al foil was coated 8 times. The electrical properties of the samples, such as specific capacitance, leakage current, and withstanding voltages, were also characterized after anodization at 100 V and 600 V. The capacitances of samples with $ZrO_2$ coating were 36.3% and 27.5% higher than those of samples without $ZrO_2$ coating when anodized at 100 V and 600 V, respectively.