• 한국진공학회지
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• 제12권3호
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• pp.193-199
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• 2003

아크-마그네트론 복합 공정법에 의해 Cu, Ag 도핑된 TiN 나노 복합 화합물 박막을 합성하고 각 금속원소 종류 및 함량에 따른 기계적 특성 및 나노 구조로의 상변화 거동을 관찰하였다. 합성된 박막은 약 40 ㎬의 높은 경도치를 나타내었으며 2 at% 미만의 낮은 금속 원소 함량에서 최대 경도간을 나타내었다. 금속 원소 함량이 증가할수록 결정립 미세화 및 다결정화가 진행되어 초고경도 특성을 나타내는 나노구조 박막이 합성되었으며 도핑되는 금속원소 종류에 따라 나노 구조로의 상변화 기구가 상이함을 관찰하였다. TiN 박막내 도핑된 Cu는 Ti와 일부 결합을 이루면서 Ti의 자리를 치환하는 것으로 나타났으나, Ag는 Ti와 결합을 이루거나 Ti 격자 자리를 치환하는 것이 아니라 독립적으로 결정립계에 존재하여 charge transfer만을 발생시키는 것으로 관찰되었다.

• 한국표면공학회지
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• 제44권5호
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• pp.213-219
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• 2011

Recently aspheric lenses are widely used for superpricision optical instruments, such as cellular phone camera modules, digital cameras and optical communication modules. The aspherical lenses are processed using mold core under high temperature compressive forming pressure. It is imperative to develop superhard protective films for the life extension of lens forming mold core. Especially ta-C films with higher $sp^3$ fractions receive attentions for the life extension of lens forming mold and, in turn, the cost reduction of lenses due to their suprior high temperature stability, high hardness and smooth surfaces. In this study ta-C films were processed on WC mold as a function of substrate bias voltage using FVA (Filtered Vacuum Arc) method. The processed films were characterized by Raman spectroscopy and nano-indentation to investigate bonding nature and hardness, respectively. The film with maximun 87% of $sp^3$ fraction was obtained at the substrate bias voltage of -60 V, which was closest to ta-C film. ta-C films showed better high temperature stability by sustaining relatively high fraction of $sp^3$ bonding even after 2,000 glass lens forming applications.

• 한국표면공학회지
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• 제39권6호
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• pp.245-249
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• 2006

In this study, ternary Ti-Mo-N and new quaternary Ti-Mo-Si-N coatings were synthesized on steel substrates(AISI D2) and Si wafers by a hybrid coating system of arc ion plating (AIP) using Ti target and d.c. magnetron sputtering technique using Mo and Si targets in $N_2/Ar$ gaseous mixture. Ternary Ti-Mo-N coatings were substitutional solid-solution of (Ti, Mo)N and showed maximum hardness of approximately 30 GPa at the Mo content of ${\sim}10$. %. The Ti-Mo-Si-N coating with the Si content of 8.8 at. % was a composite consisting of fine (Ti, Mo)N crystallites and amorphous $Si_3N_4$ phase. The hardness of the Ti-Mo-Si(8.8 at. %)-N coatings exhibited largely increased hardness value of ${\sim}48$ GPa due to the microstructural evolution to the fine composite microstructure and the refinement of (Ti, Mo)N crystallites. The average friction coefficient of the Ti-Mo-Si-N coatings largely decreased with increase of Si content. The microstructures of Ti-Mo-Si-N coatings were investigated with instrumental analyses of XRD, XPS, and HRTEM in this work.

• The Korean Journal of Ceramics
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• 제3권1호
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• pp.1-4
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• 1997

Diamond film (24$\mu\textrm{m}$) were prepared by Microwave Plasma Chemical Vapor Deposition method from a reactive CO/H$_2$ mixtures. Micro-Raman spectroscopy and micro-cathodoluminescence study were carried out along the crosssection and correlated to SEM observation. CL image of cross-section was also investigated. Peak position, FWHM of Raman spectrum were determined using Lorentzing fit. The stress in this sample is 0.4~0.7 GPa compressive stress, and along the distance the compressive stress reduced. The Raman peak broadening is dominated by phonon life time reduction at grain boundaries and defect sites. Defects and impurities were mainly present inside the film, not at Silicon/Diamond interface.

• Journal of Welding and Joining
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• 제20권1호
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• pp.47-54
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• 2002

Powder type Ag system insert metals were manufactured by ball milling process. The variables of milling process such as milling media, revolution speed and powder/ball weight ratio were constant except the milling time. The milling times were selected for 24, 48 and 72 hours. The insert metals made by milling process were evaluated by performing scanning electron microscope, x-ray and DSC(differential scanning calorimetry) analysis, and further in terms of wettability test. The selected insert metals that have the good characteristics compared to commercial insert metals were applied to make the brazed joints of the steel/steel and the steel/WC superhard particles. The characterizations of those brazed joints were also conducted by microstructural observations, shear tensile tests and microhardness measurements. The results indicated that milling time of 48 hours for making powder type insert metals was the best condition showing the small amount of oxides residue, low wetting angle and stable microstructure. The brazed joints that applied the 48 hours milled insert metal were very sound condition indicating the shear tensile value of $2.29{\times}102$ MPa and the microhardness of 138VHN. Further, the amount of the porosity was appeared to be lower than that of the commercial insert metals.

• 한국표면공학회지
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• 제38권3호
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• pp.100-105
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• 2005

Cr-Si-C-N coatings were deposited on steel substrate (SKD 11) by a hybrid system of arc ion plating (AIP) and sputtering techniques. From XRD, XPS, and HRTEM analyses, it was found that Cr-Si-C-N had a fine composite microstructure comprising nano-sized crystallites of Cr(C, N) well distributed in the amorphous phase of $Si_3N_4/SiC$ mixture. Microhardness of Cr(C, N) coatings and Cr-Si-N coatings were reported about $\~22 GPa$ and $\~35 GPa$, respectively. As the Si was incorporated into Cr(C, N) coatings, The Cr-Si-C-N coatings having a Si content of $9.2 at.\%$ showed the maximum hardness value. As increased beyond Si content of $9.2 at.\%$, the interaction between nanocrystallites and amorphous phase was gone, the hardness was reduced as dependent on amorphous phase of $Si_3N_4/SiC$. In addition, the average coefficient of Cr-Si-C-N coatings largely decreased compared with Cr(C, N) coatings.