• Journal of the Korean institute of surface engineering
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• v.57 no.1
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• pp.14-21
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• 2024

For this study, CrAlN multilayer coatings were deposited on SKD61 substrates using a multi-arc ion plating technique. The structural characteristics of the CrAlN multilayer coatings were evaluated using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Additionally, the adhesion of the coatings was assessed through scratch testing, and the mechanical strength was evaluated using nanoindentation and tribometric tests for frictional properties. The results show that the CrAlN multilayer coatings possess a uniform and dense structure with excellent mechanical strength. Hardness measurements indicated that the CrAlN coatings have high hardness values, and both the coating adhesion and wear resistance were found to be improved compared to CrN. The addition of aluminum is anticipated to contribute to enhanced durability and wear resistance.

• Journal of the Korean Society of Radiology
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• v.4 no.1
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• pp.25-30
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• 2010

The objective of this study was to compare the resolution and density appropriate to diagnosis in chest PA radiography. In comparing the resolution, we radiographed with conventional radiography, computed radiography(CR) and digital radiography(DR) using the linear resolution phantom(Nuclear Associates-Carle Place. N.Y.). 2 radiologists and 3 radiological technologists read the resolution value by the blind test. DR, conventional radiography and CR measured 3.95, 3.58, 3.48 resolution value respectively. In analysing the density, we chose the fifty normal chest CR and DR and conventional film. We estimated the density using by densitometer(X-rite company-Model 301) in seven regions(lung field, lung field margine, mediastinum I, mediastinum II, heart shadow I, heart shadow II, diaphragm) of chest film. We adapted to analysis the Japanese chest X-ray evaluating method and table. It was scored 0(farthest density value) to 2(nearest density value). DR scored 2 at mediastinum I, mediastinum II, heart shadow I, heart shadow II and diaphragm. On the contrary with, CR scored 2 at lung field and lung field margine. Consequently, DR superior than CR and conventional radiography film compairing density and resolution. It was due to small pixel size and post processing algorithm with digital radiography.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.135-141
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• 1994

With the variation of Cr content and $N_2$ flow ratio, the soft magnetic properties, corrosion resistance and reactivity of the sputtered nanocrystalline FeZrCrN thin flims were investigated. In case of FeZrCrN thin films, a saturation magnetization was decreased with increasing $N_2$ flow ratio. In addition, good soft magnetic properties were obtained at the flow ratio of 3% $N_2$. The $Fe_{64.9}Zr_{8.8}Cr_{5.8}N_{20.5}$ nanocrystalline thin film after annealing at $550^{\circ}C$ exhibited the saturation magnetization of 12.5kG, low coercivity of 0.4 Oe and high permeability of 2600 at 5 MHz. Films containing up to 7.5% Cr showed an enhanced corrosion resistance and reduced reactivity with the bonding glass without degradation of soft magnetic properties, although the saturation magnetization was decreased slightly with the Cr addtion.

• Journal of the Korean Ceramic Society
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• v.45 no.3
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• pp.161-166
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• 2008

The multi-films of a metallic film and a transparent conducting oxide (TCO, indium-tin oxide, ITO) film were formed on the stainless steel 316 and 304 plates by a sputtering method and an E-beam method and then the external metallic region of the stainless steel bipolar plates was converted into the metal nitride films through an annealing process. The multi-film formed on the stainless steel bipolar plates showed the XRD patterns of the typical indium-tin oxide, the metallic phase and the metal substrate and the external nitride film. The XRD pattern of the thin film on the bipolar plates modified showed two metal nitride phases of CrN and $Cr_2N$ compound. Surface microstructural morphology of the multi-film deposited bipolar plates was observed by AFM and FE-SEM. The metal nitride film formed on the stainless steel bipolar plates represented a microstructural morphology of fine columnar grains with 10 nm diameter and 60nm length in FE-SEM images. The electrical resistivity of the stainless steel bipolar plates modified was evaluated.

• Corrosion Science and Technology
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• v.9 no.1
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• pp.20-28
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• 2010

According to the bipolar model, ion selectivity of some species in the passive film is important factor to control the passivation. An increase of cation selectivity of outer layer of the passive film can stabilize the film and improves the corrosion resistance. Therefore, the formation and roles of ionic species in the passive film should be elucidated. In this work, two types of solution (hydrochloric or sulfuric acid) were used to test high N and Mo-bearing stainless steels. The objective of this work was to investigate the formation of oxyanions in the passive film and the roles of oxyanions in passivation of stainless steel. Nitrogen exists as atomic nitrogen, nitric oxide, nitro-oxyanions (${NO_x}^-$), and N-H species, not nitride in the passive film. Because of its high mobility, the enriched atomic nitrogen can act as a reservoir. The formation of N-H species buffers the film pH and facilitates the formation of oxyanions in the film. ${NO_x}^-$ species improve the cation selectivity of the film, increasing the oxide content and film density. ${NO_x}^-$ acts similar to a strong inhibitor both in the passive film and at active sites. This facilitates the formation of chromium oxide. Also, ${NO_x}^-$ can make more molybdate and nitric oxide by reacting with Mo. The role of Mo addition on the passivation characteristics of stainless steel may differ with the test environment. Mo exists as metallic molybdenum, molybdenum oxide, and molybdate and the latter facilitates the oxide formation. When nitrogen and molybdenum coexist in stainless steel, corrosion resistance in chloride solutions is drastically increased. This synergistic effect of N and Mo in a chloride solution is mainly due to the formation of nitro-oxyanions and molybdate ion. Oxyanions can be formed by a 'solid state reaction' in the passive film, resulting in the formation of more molybdate and nitric oxide. These oxyanions improve the cation selectivity of the outer layer and form more oxide and increase the amount of chromium oxide and the ratio of $Cr_2O_3/Cr(OH)_3$ and make the film stable and dense.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.7-9
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• 2007

Thin films of CrAlSiN were deposited on SKD11 tool steel substrate using Cr and AlSi cathodes by a cathodic arc plasma deposition system. The influence of process parameters on the deposited film properties were investigated. The oxidation characteristics of the films were studied at temperatures ranging from 800 and 1000+C up to 50 h in air. The films showed superhardness and good oxidation resistance..

• Proceedings of the Korean Vacuum Society Conference
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• 1994.02a
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• pp.65-67
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• 1994

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1301-1307
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• 1995

Pitting corrosion of TiN film deposited on Inconel 600 by plasma assisted chemical vapor deposition (PACVD) was investigated. Cyclic potentiodynamic polarization (CPP) tests were conducted in order to determine the pit nucleation potentials, Enp, of the TiN-deposited sample and the bare Inconel 600 in deaerated NaCl solution at 25, 135 and 20$0^{\circ}C$. The effects of the TiN film thickness, the solution temperature and the Cl- concentration on Enp were studied. Enp of the TiN-deposited sample which had the film thickness above 1${\mu}{\textrm}{m}$ were higher than those of the bare Inconel 600 by 300~600mV at all the solution temperatures, implying the pitting resistance improvement of the TiN film. The morphologies of the pits generated after immersion test were examined with a scaning electron microscopy. The higher was the solution temperature, the more corrosion products, mainly composed of Cr and Ni oxides, were formed.

• Journal of the Korean institute of surface engineering
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• v.45 no.3
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• pp.123-129
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• 2012

Nanocrystalline CrN coatings were fabricated by DC and ICP (inductively coupled plasma) assisted magnetron sputtering techniques. The effect of ICP power, ranging from 0 to 500 W, on coating microstructure, preferred orientation mechanical properties were systematically investigated with HR-XRD, SEM, AFM and nanoindentation. The results show that ICP power has an significant influence on coating microstructure and mechanical properties of CrN coatings. With the increasing of ICP power, coating microstructure evolves from the columnar structure of DC process to a highly dense one. Grain size of CrN coatings were decreased from 11.7 nm to 6.6 nm with increase of ICP power. The maximum nanohardness of 23.0 GPa was obtained for the coatings deposited at ICP power of 500 W. Preferred orientation in CrN coatings also vary with ICP power, exerting an effective influence on film nanohardness.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.646-648
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• 2008

The multi-films of a metallic film and a transparent conducting oxide (TCO, indium-tin oxide, ITO) film were formed on the stainless steel 316 and 304 plates by a sputtering method and an E-beam method and then the external metallic region of the stainless steel bipolar plates was converted into the metal nitride films through an annealing process. The multi-film formed on the stainless steel bipolar plates showed the XRD patterns of the typical indium-tin oxide, the metallic phase and the metal substrate and the external nitride film. The XRD pattern of the thin film on the bipolar plates modified showed two metal nitride phases of CrN and $Cr_2N$ compound. Surface microstructural morphology of the multi-film deposited bipolar plates was observed by AFM and FE-SEM. The electrical resistivity of the stainless steel bipolar plates modified was evaluated.