• Journal of the Korean institute of surface engineering
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• v.35 no.1
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• pp.5-10
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• 2002

This study was performed to investigate the influence of spraying condition to the coating layer properties of Fe-Cr-Ni-Mo-Si-B alloy using the HVOF. The investigations, such as thickness measurement, surface roughness, hardness, friction coefficient, resistance of corrosion were carried out. Matrix is prepared by gritting and coating layer is made of Fe-Cr-Ni-Mo-Si-B alloy powder using HVOF. Alumina gritting layers are superior to steel gritting layers. The less spaying distance, the more coating layer properties confirmed. The optimum spraying condition, in this study, was proved as 13inch spraying distance with feed rate 350rpm (78g/min).

• Journal of the Korean Ceramic Society
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• v.41 no.6
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• pp.450-455
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• 2004

NiCr thin films were fabricated by thermal evaporation method using NiCr alloy as evaporating source. NiCr thin films were annealed at various temperatures in air atmosphere in order to investigate effects of annealing conditions on phase change, composition, and microstructures of NiCr films. Typical multilayer was formed after annealing in air atmosphere. This results from the diffusion and oxidation of Cr toward surface during annealing. In the case of annealing at 700$^{\circ}C$, large columnar grains of NiO were formed on Cr-oxide layer through the diffusion and oxidation of Ni over Cr-oxide layer. Especially, NiO layer was formed additionally on surface, sustaining the underlayer structure with the formation of porous Ni layer.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.164-169
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• 2000

The remote measurement system(RMS) as a new experimental method is limited in its application to crack measurements at elevated temperatures because of the oxide layer on the specimen surface. Since TiAlN and Cr coating layers have a high resistance to oxidation and wear, this paper proposed a TiAlN and Cr coating technique for specimens to facilitate the measurement of crack growth behavior using RMS. To investigate the effects of the coating layer, tension and fatigue tests were carried out at room temperature and at 538$^{\circ}C$, using specimens of 1Cr-1Mo-0.25V steel. From the experimental results, it was found that the mechanical properties of the TiAlN and Cr coated specimens were similar to those of the substrate. Accordingly, the TiAlN and Cr coated layer had hardly any influence on the fatigue crack propagation.

• Journal of the Korean institute of surface engineering
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• v.47 no.2
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• pp.63-67
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• 2014

As the demand for fine-pitch FPCB (Flexible Printed Circuit Board) increases, so do the number of applications of sputtered FCCL (Flexible Copper Clad Laminate). Furthermore, as the width between the circuit patterns decreases, greater defects are observed in the migration phenomenon. In this study we observed changes in ion migration in real circuit-pattern width using sputtered FCCL. We found that as the applied voltage and residue thickness of the NiCr seeds increase, ion migration occurs faster. If the NiCr seed layer thickens due to a high cathode power and long deposition time while being sputtered, the NiCr will form a residue that quickly becomes a factor for incurring ion migration.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.60-66
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• 2002

The remote measurement system(RMS) as a new experimental method is limited in its application to crack measurement at elevated temperatures because of the oxide layer on the specimen surface. Since TiAIN and Cr coating layers have a high resistance to oxidation and wear, this paper proposed a TiAIN and Cr coating technique for specimens to facilitate the measurement of crack growth behavior using RMS. To investigate the effects of the coating layer, tension and fatigue tests were carried out at room temperature and at $538^{\circ}C$. The test material was 1Cr-1Mo-0.25V steel which is widely used as a turbine rotor material. From the experimental results, it was found that the mechanical properties of the TiAIN and Cr coated specimens were similar to those of the substrate. Accordingly, the TiAIN and Cr coated layer had hardly any influence on the fatigue crack propagation.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3535-3542
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• 2023

Eutectic reactions of five kinds of Cr-coated Zr alloy cladding with different base materials (Zr-Nb-Sn alloy or Zr-Nb alloy), different coating thicknesses (6~22.5 mm), and different coating materials (Cr single layer or Cr/CrN bilayer) were studied using Differential Scanning Calorimetry (DSC). The DSC experiments demonstrated that the onset temperatures of the Cr single layer coated specimens were almost identical to ~1308 ℃, regardless of base materials or coating thicknesses. This study demonstrated that the Cr/CrN bilayer coated Zr-Nb-Sn alloy has a slightly (~10 ℃) higher eutectic onset temperature compared to the single Cr-coated specimen. The eutectic region characterized by post-eutectic microstructure proportionally increases with coating thickness. The post-eutectic characterization with different holding times at high temperature (1310-1330 ℃) reveals that progression of Zr-Cr eutectic requires time, and it dramatically changed with exposure time and temperature. The practical value of the time gain in non-instantaneous eutectic formation in terms of safety margin, however, seems to be limited.

• Electronics and Telecommunications Trends
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• v.21 no.4 s.100
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• pp.62-69
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• 2006

유비쿼터스 정보화사회의 도래와 함께 한정된 주파수자원에 대한 수요가 증가됨에 따라 이를 효율적으로 이용하기 위한 기술이 더욱 각광을 받고 있다. 이중에서도 스펙트럼 환경을 측정하여 사용하지 않은 주파수를 선정, 기존의 전파환경과 양립하면서 통신을 하는 CR 기술은 미래 무선통신의 핵심 기술로 인식되고 있다. CR 기술은 SDR 기술을 기반으로 스펙트럼 센싱(spectrum sensing) 기능을 활용하여 가용한 주파수를 선정하여 통신하는 기본적인 기능과 여러 가지 환경 파라미터를 지속적으로 업데이트하는 learning algorithm이 합쳐진 기술이다. 본 고에서는 CR 기술을 설명하고, CR의 응용으로 현재 표준화가 진행되고 있는 IEEE 802.22 WRAN 표준화 활동과 WG에서 검토되고 있는 기술, 즉 physical layer, MAC layer, 그리고 spectrum sensing의 주요기술을 소개한다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.101-107
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• 2004

각종 전자기기의 소형화, 고성능화 요구에 따라 회로 또는 기판의 고집적화에 따른 대안으로 도입된 COF(Chip On Film)공정에서 PI(polyimide)/buffer layer/Cu의 접착력 개선을 목적으로 본 연구가 진행 되었다. 그리고 buffer layer로써 Cr을 증착 할 때 부착력의 개선을 목적으로 개질처리를 할 때는 RF plasma장비를 사용하였다. 실험 변수로는 peel strength에 대한 buffer layer의 종류와 증착시간, 표면 개질처리시 $O_2$/Ar비이다. Buffer layer의 종류에 따른 접착력은 Cr보다 Ni이 우수하였고 peel strength와 Cu THK는 같은 buffer layer의 증착 structure에서 비례 관계를 나타냈으며, Cr의 증착 시간과 Cu의 증착 시간을 변수로 peel strength test한 값은 Cr증착시간이 30초, Cu증착시간이 20분일때 40g/mm로 최적의 접착력이 나타났다. 증착전 PI의 개질 처리시 $O_2$/Ar 유량비에 따른 peel strength값은 $O_2$/Ar유량비가 증가 할수록 향상되었으며, 2/5에서 최고값인 58g/mm가 나타났다. 그 이상에서는 오히려 감소하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.166-168
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• 2007

스퍼터링법으로 제작된 FCCL은 PI필름(Poly-imide film)과 Cu layer사이에 Tie-coating layer로 Ni-Cr을 많이 사용한다. 하지만 완성된 FCCL에서 페터닝을 실시할 때 Cr성분이 소멸되지 않고 잔존하는 현상으로 누설전류가 발생 한다. 또한 Cr으로 인해 Eatching액의 오염으로 재사용의 어려움도 발생된다. 이러한 원인들은 제품의 특성들을 저하 시키므로 이를 개선할 필요가 있다. 따라서 본 연구에서는 기존의 Tie-coating layer를 대체할 물질로 Acrylic acid를 이용하여 FCCL을 제작하여 표면특성 평가를 위해 Contact angle측정과 부착력을 위한 Peel test측정과 조직분석 및 성분분석을 위해 SEM-EDS를 측정을 통하여 Polymerization을 이용한 Ti-coating layer 개발의 가능성을 확인하였다.

• Korean Journal of Materials Research
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• v.27 no.10
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• pp.563-568
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• 2017

In this study, the coating of an Al-Cr layer on the surface of a Zircaloy-4 alloy was carried out through plasma pretreatment coating and a laser surface melting process. Two different conditions for laser treatment, severe or minimal surface melting of the Zr alloy substrate, were applied to form the final coating. When there was significant surface melting of the Zr alloy, the solidification microstructure of the newly formed coating layer was mainly composed of needle-shaped $Al_3Zr$, Al(Cr) and $Al_7Cr$ phases. On the other hand, the solidification microstructure of the coating layer was mainly composed of Al(Cr) and $Al_7Cr$ phases when there was minimal surface melting of Zr base in the laser process. However, when the coating was maintained at $1100^{\circ}C$ for 2 hours, significant inter-diffusion occurred between the phases in the coating. As a result, the upper part of the coating layer was observed to mainly consist of $Al_3Zr$ and $Al_8Cr_5$ phases, regardless of the laser treatment conditions.