• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.10a
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• pp.24-24
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• 1997

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.04a
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• pp.19-20
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.171-171
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• 2000

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.54-55
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• 1999

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.13-14
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• 2000

• Journal of Surface Science and Engineering
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• v.44 no.5
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• pp.190-195
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• 2011

Diamond-like carbon (DLC) has many outstanding properties such as low friction, high wear resistance and corrosion resistance. However, it is difficult to achieve enough adhesion on the metal substrates because of weak bonding between DLC film and the metal substrate. The purpose of this study is to enhance an adhesion of DLC film. For improving adhesion, the substrate was treated by active screen plasma nitriding before DLC film deposing. Nitrided substrates were investigated by Glow Discharge Spectrometer (GDS), Micro-Vickers Hardness. DLC films were deposited on several metals by linear ion source, and characteristics of the films were investigated using nano-indentation, Field Emission Scanning Electron Microscope (FESEM). The adhesion was measured by scratch tester. The adhesion of DLC films was increased when nitriding layer was formed before DLC deposition. Therefore, the adhesion of DLC film can be enhanced as increasing the hardness of materials.

• Journal of Surface Science and Engineering
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• v.51 no.1
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• pp.54-61
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• 2018

Plasma Nitriding treatment was performed on STS 204Cu stainless steel samples at a temperature of $400^{\circ}C$ for 15 hours with varying $N_2$ content as 10%, 15% and 25%. Regardless of the content of $N_2$, S-Phase which is a hardened layer of Nitrogen (N) supersaturated phase, was formed in the surface of plasma treated samples. When $N_2$ content was 25%, the thickness of the hardened layer reached up to about $7{\mu}m$ and the surface hardness reached a value of $560Hv_{0.05}$, which is about 2.5 times higher than that of untreated sample (as received $220Hv_{0.05}$). From potentiodynamic polarization test, it was observed that compared to as received sample, the corrosion potential and the corrosion current density of the plasma treated samples were decreased regardless of the $N_2$ content, but the corrosion resistance was not increased much due to the precipitation of $Cr_2N$. On the other hand, pitting potential of the samples treated with 10% and 15% $N_2$ was higher than that of as received sample, however, the samples treated with 25% exhibited a lower pitting potential. Therefore, 10% $N_2$ content was selected as optimum plasma nitriding condition and to further increase both the thickness and surface hardness and the corrosion resistance of the hardened layer, different $CH_4$ content such as 1%, 3% and 5% was introduced into the plasma nitriding atmosphere. With 1% $CH_4$, the thickness of the hardened layer reached up to about $11{\mu}m$ and the surface hardness was measured as about $620Hv_{0.05}$, which is about 2.8 times that of as received sample. And the corrosion resistance of the plasma treated sample by using 1% $CH_4$ was improved significantly due to much higher pitting potential, and lower corrosion current density. When the $CH_4$ content was more than 1%, the thickness and surface hardness of the hardened layer decreased slightly and the corrosion resistance also decreased.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.174-179
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• 2003

Thin copper films were grown by electrodeposition on copper seed layers which were grown by sputtering of an ultra-pure copper target on tantalum nitride-coated silicon wafers and subsequently, cleaned in ECR plasma. The copper films were then subjected to ⅰ) vacuum annealing, ⅱ) rapid thermal annealing (RTA) and ⅲ) rapid thermal nitriding (RTN) at various temperatures over different periods of time. XRD, SEM, AFM and resistivity measurements were done to ascertain the optimum heat treatment condition for obtaining film with minimum resistivity, predominantly (111)-oriented and smoother surface morphology. The as-deposited film has a resistivity of ∼6.3 $\mu$$\Omega$-cm and a relatively small intensity ratio of (111) and (200) peaks. With heat treatment, the resistivity decreases and the (111) peak becomes dominant, along with improved smoothness of the copper film. The optimum condition (with a resistivity of 1.98 $\mu$$\Omega$-cm) is suggested as the rapid thermal nitriding at 400oC for 120 sec.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1468-1475
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• 2023

Enhancement of wear resistance of components used in fast reactors is necessary for long service life of the components. Plasma nitriding is a promising surface modification technology to impart high hardness and improved wear resistance of various steel components. This study discusses the characterization of chrome nitrided SS316L casing ring used in secondary sodium pump of fast breeder reactor and its stability under long term sodium exposure. Microstructural and hardness analysis showed that stress relieved component could be chrome nitrided successfully to a thickness of about 100 ㎛. Assessment of in-sodium performance of the chrome nitrided casing ring subjected to long term exposure up to 5000h at 550℃, showed retention of chrome nitrided layer with a case depth almost similar to that before sodium exposure. A slight decrease in the hardness was observed due to prolonged high temperature sodium exposure. Tribological studies indicate very low coefficient of friction indicating the retention of good wear resistance of the coating even after long term sodium exposure.

• Journal of Surface Science and Engineering
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• v.38 no.3
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• pp.126-135
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• 2005

SKD 11 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness and creep strength as well as excellent oxidation resistance. The ion nitrided tool steel containing Mo results in improvement of corrosion resistance, strength at high temperature and pitting resistance, especially in $Cl^-$ contained environment. But the Mo addition causes a disadvantage such as lower oxidation resistance at elevated temperature. In this study, several effects of ion-disadvantage on the oxidation characteristics for SKD 11 steel with various oxidation temperature were investigated. SKD 11 steels were manufactured by using vacuum furnace and solutionized for 1 hr at $1,050^{\circ}C$. Steel surface was ion nitrided at $500^{\circ}C$ for 1 hr and 5 hr by ion nitriding equipment. ion nitrided specimen were investigated by SEM, OM and hardness tester. Oxidation was carried out by using muffle furnace in air at $500^{\circ}C,\;700^{\circ}C\;and\;900^{\circ}C$ for 1hr, respectively. Oxidation behavior of the ion nitrided specimen was investigated by SEM, EDX and surface roughness tester. The conclusions of this study are as follows: It was found that plasma nitriding for 5 hr at $500^{\circ}C$, compared with ion nitriding for 1 hr at $500^{\circ}C$, had a thick nitrided layer and produced a layer with good wear, corrosion resistance and hardness as nitriding time increased. Nitrided SKD 11 alloy for 1hr showed that wear resistance and hardness decreased, whereas surface roughness increased, compared with nitrided SKD 11 alloy for 5 hr. The oxidation surface at $900^{\circ}C$ showed a good corrosion resistance.