• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.177-179
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• 2011

The purpose of this study is to enhance an adhesion between substrate and Diamond-like Carbon (DLC) film. DLC has many outstanding properties such as low friction, high wear resistance and corrosion resistance. However, it is difficult to achieve enough adhesion because of weak bonding between DLC film and the substrate. For improvement adhesion, a layer between DLC film and the substrate was prepared by dual post plasma. DLC film was deposited on nitrided layer by linear ion source. The composed compound layer between substrate and DLC film was investigated by Glow Discharge Spectrometer (GDS) and Scanning Electron Microscope (SEM). The synthesized bonding structure of DLC film was analyzed using a micro raman spectrometer. Mechanical properties were measured by nano-indentation. In order to clarify the mechanism for improvement in adhesive strength, it was observed by scratch test.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.85-91
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• 2006

The fraction of $\varepsilon\;and\;\gamma$'-iron nitride in compound layer is predicted by x-ray diffraction using direct comparison method. The validity of formulation models was checked by comparing calculated results with metallographic analysis of iron nitride compound layer grown on steel S45C by gas nitriding. The fraction of $\varepsilon$ calculated by the three phase model, porous-$Fe_3N$/ dense-$Fe_3N$/ mixed layer with $Fe_3N\;and\;Fe_4N$, is 80 percent of that analyzed by etching technique. The $\varepsilon$ fraction predicted by mixed layer model is 122 percent of that measured by microscope.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.6
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• pp.371-377
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• 2001

스테인리스강의 주요 특징은 우수한 내식성에 있다. 그럼에도 불구하고 스테인리스강은 질화시키면 스테인리스강의 주요 특징인 내식성의 저하가 불가피하다. 그러나 경우에 따라서는 내식성이 다소 희생되더라도 내모성 향상을 목적으로 SUS 304소재를 이용한 피스톤링이나 SUS 420 J2소재를 사용하는 마이크로 샤프트 등과 같은 많은 제품에 대하여 질화처리를 실시하고 있다. 스테인리스 제품에 얼룩이 없는 질화처리를 실시하기 위해서는 앞에서 소개한 방법 이외에 표면활성화를 위한 분말처리법 등이 많이 사용되고 있으며, 그 예로 일본의 마테크(주)에서 제조하여 (주)사마루에서 시판하고 있는 활성분체질화제(APN법, DCA)을 사용하여 질화시키는 방법등도 있다. 이와 같이 외국에서는 프라즈마법이 아닌 일반 가스질화에 의한 스테인리스강의 질화에 대한 많은 연구가 이루어지고 산업화 되어 있지만 현재 국내에서는 이에 대한 연구가 거의 이루어지고 있지 않은 실정이다. 따라서 앞으로는 국내에서도 이러한 분야에 대한 보다 많은 관심과 연구 및 기술보고 등이 활성화되어야 할 것으로 생각된다.

• Journal of the Korean institute of surface engineering
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• v.50 no.4
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• pp.272-276
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• 2017

The response of AISI 310 type austenitic stainless steel to the novel low temperature plasma carburizing process has been investigated in this work. This grade of stainless steel shows better corrosion resistance and high temperature oxidation resistance due to its high chromium and nickel content. In this experiment, plasma carburizing was performed on AISI 310 stainless steel in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-Ar-CH_4$ gas mixtures. The working pressure was 4 Torr (533Pa approx.) and the applied voltage was 600 V during the plasma carburizing treatment. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. The phase of carburized layer formed on the surface was confirmed by X-ray diffraction. The resultant carburized layer was found to be precipitation free and resulted in significantly improved hardness and corrosion resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.175-177
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• 2012

A corrosion resistance and hard nitrocarburized layer was distinctly formed on 310 austenitic stainless steel substrate by DC plasma nitrocarburizing. Basically, 310L austenitic stainless steel has high chromium and nickel content which is applicable for high temperature applications. In this experiment, plasma nitrocarburizing was performed in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-N_2-CH_4$ gas mixtures. After the experiment structural phases, micro-hardness and corrosion resistance were investigated by the optical microscopy, X-ray diffraction, scanning electron microscopy, micro-hardness testing and Potentiodynamic polarization tests. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. XRD indicated a single expanded austenite phase was formed at all treatment temperatures. Such a nitrogen and carbon supersaturated layer is precipitation free and possesses a high hardness and good corrosion resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.189-189
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• 2012

여기서는 오스테나이트 스테인리스강에 내구성능을 부여하기 위하여 여러 가지 공정온도 조건 중에서 플라즈마 이온질화 처리하여 질화층을 제작하였다. 이와같은 이온질화 층들에 대해서 형성기구를 해석함을 물론 경도, 마모 및 충격 시험들의 기계적 특성과 염수분무시험(Salt Spray Test), 침지 자연전위($E_{coor}$), 전기화학적 양분극 부식 특성을 평가하였다. 이들 층은 표면, 경화 깊이, 미세조직 및 결정구조를 분석하였고, 질화층 표면의 기계적 특성 및 부식 특성과의 상관관계를 해명-정리하였다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.357-362
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• 2001

The purpose of this study is to investigate the effect of nitriding on the fatigue strength and fatigue life of turbine rotor steel (ICr-lMo-0.25V), and acquire data on the fatigue strength of nitrided turbine rotor steel at high temperature (538$^{\circ}C$). Specimens were nitrided with various layer thicknesses (160$\mu$m, 270$\mu$m and 290$\mu$m) using the nitemper method. A microstructure analysis, microhardness test, surface roughness test, and fracture surface analysis were also carried out at room temperature in order to investigate the mechanical properties of the nitrided specimens.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.184-190
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• 1988

ZrN powder was prepared from the powder mixture of ZrCl4 and Al by the halogenide process in nitrogen gas flow (100-150ml/min) at the temperatures from 200$^{\circ}$to 1050$^{\circ}C$. ZrN powder was formed about 600$^{\circ}C$ and in the slow nitriding reaction, however, an intermediate product of Al3Zr was formed. The fine powder (0.1-10$\mu\textrm{m}$) of single phase ZrN was obtained at 1050$^{\circ}C$ after 1 hour. The lattice parameter and crystallite size of ZrN were 4.5787A and 360A, respectively. According to SEM observation, the particles were apt to agglomerates. The apparent activation energy for the formation of ZrN was approximately 13.2kcal/mole(750$^{\circ}$-1000$^{\circ}C$).

• Journal of the Korean Ceramic Society
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• v.44 no.7
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• pp.354-357
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• 2007

The nitriding and post-sintering behavior of silicon powder compact containing sintering additives of 2.3 wt% and 7 wt% were investigated in this study. Regardless of the liquid phase content, elongated large grains of a typical morphology evolved in the post-sintered specimens. Phase analysis revealed a complete phase transformation into ${\beta}-Si_3N_4$ in both porous systems. Oxynitride second phases (mellilite) precipitated in the latter, while those were free in the former containing less amount of liquid phase. The post-sintering condition that yielded a favorable microstructure for a filter application was achieved when the specimens were soaked at $1800^{\circ}C$ for 2 h. It was found that the thermal conductivity of porous $Si_3N_4$ ceramics is dominated by the porosity more than this factor is influenced by the addition of $Al_2O_3$.

• Journal of the Korean institute of surface engineering
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• v.43 no.3
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• pp.154-158
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• 2010

Numerical analysis is done to investigate the effects of pulse bias on the plasma processing characteristics like ion doping and ion nitriding by using fluid dynamic code with a 2D axi-symmetric model. For 10 mTorr of Ar plasma, -1 kV of pulse bias was simulated. Maximum sheath thickness was around 20 mm based on the electric potential profile. The peak electron temperature was about 20 eV, but did not affect the averaged plasma characteristics of the whole chamber. Maximum ion current density incident on the substrate was 200 $A/m^2$ at the center, but was decreased down to 1/10th at radius 100 mm, giving poor radial uniformity.