• Journal of the Korean Society for Heat Treatment
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• v.22 no.5
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• pp.267-274
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• 2009

Titanium Chromium Nitrided (TiCrN) coatings were deposited on stainless steel 316 L and Si (100) wafer by inductively coupled plasma assisted D.C. magnetron sputtering at the various sputtering power on Cr target and $N_2/Ar$ gas ratio. Increasing the sputtering power of Cr target, XRD patterns were changed from TiCrN to nitride $Cr_2Ti$. The maximum hardness was $Hk_{3g}$ 3900 at $0.3\;N_2/Ar$ gas ratio. The thickness of the TiCrN films increased as the Cr target power increased, and it showed over $Hk_{5g}3100$ hardness at 100 W, 150 W. TiCrN films were deposited by the ICP assisted DC magnetron sputtering shown good wear resistance as the $N_2/Ar$ gas ratio was 0.1, 0.3.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.291-297
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• 1999

The plasma etching of tungsten thin films has been studied with $SF_6$ gas in RIE system. The etch rate of ${\alpha}$-phase W film with $SF_6$ gas plasma has been showed to depend strongly on process parameters ($SF_6$, $SF_6-N_2$ gas). Effect of $N_2$ addition and etching selectivity between W film and photoresist have also been studied in detail. Etching profiles between W film and photoresist were investigated by SEM. The compounds on W surface after $SF_6-N_2$ gas plasma treatment were examined by XPS and the concentration of F ions was detected by OES during plasma on.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.2
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• pp.87-93
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• 2004

Nitrocarburizing was carried out with various $CH_4$ gas composition with 4 torr gas pressure at $570^{\circ}C$ for 3 hours and post oxidation was carried out with 100% $O_2$ gas atmosphere with 4 torr at different temperatures for various time. In the case of plasma nitrocarburizing, It is that the ratio of ${\varepsilon}-Fe_{2-3}$(N, C) and ${\gamma}^{\prime}-Fe_4$(C, N), which comprise the compound layer phase, depend on concentrations of $N_2$ gas and $CH_4$ such that when the concentration of $N_2$ and $CH_4$ increased, the ratio of ${\gamma}^{\prime}-Fe_4$(C, N) decreased, but the ratio of ${\varepsilon}-Fe_{2-3}$(N, C) increased. The thickness of compound layer consistently increased as gas concentration increased regardless of $N_2$ and $CH_4$ expect when the concentration of $CH_4$ was 3.5 volume%, it decreased insignificantly. When oxidizing for 15min in the temperature range of $460{\sim}570{^\circ}C$, the study found small amount of $Fe_3O_4$ at the temperature of $460{^\circ}C$ and also found that amounts of $Fe_2O_3$. and $Fe_3O_4$ on the surface and amount of ${\gamma}^{\prime}-Fe_4$(C, N) in the compound layer increased as the increased over $460^{\circ}C$, but the thickness of the compound layer decreased. Corrosion resistance was influenced by oxidation times and temperature.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.71-77
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• 2022

To increase biomass utilization, rice husk-based activated carbon (RHAC) followed by nitrogen plasma surface treatment was prepared and the electric double-layer capacitor performance was investigated. Through nitrogen plasma surface treatment, up to 2.17% of nitrogen was introduced to the surface of RHAC, and in particular the sample reacted for 5 min with nitrogen plasma showed dominant formation of pyrrolic/pyridine N functional groups. In addition, mesopores were formed on the RHAC material by the removal of silica, and the surface roughness of the carbon material increased by nitrogen plasma surface treatment, resulting in the formation of many micropores. As a result of cyclic voltammetry measurement, at a scan rate of 5 mV/s, the specific capacitance of the RHAC treated with nitrogen plasma increased up to 200 F/g, showing an 80.2% improvement compared to that of using untreated RHAC (111 F/g). This is attributed to the synergetic effect of the introduction of pyrrolic/pyridine-based nitrogen functional groups and the increase of the micropore volume on the surface of the carbon material. This study has a positive effect on the environment in terms of recycling waste resources and using plasma surface treatment.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.255-265
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• 1995

Stainless steel type 304L has been nitrided in the low pressure (600Pa) and high nitrogen (80% $N_2$+20% $H_2$) environment for 5 hours by the square-wave-pulsed-d.c. plasma as a function of temperature $400{\sim}550^{\circ}C$ and pulsation. At the lower temperature range of $400{\sim}500^{\circ}C$ and at the relatively high ratio of pulse duration to pulse period. "S-phase" has been developed in the form of thin nitrided surface layer which has many cracks, leading to be nearly impossible for the industrial anti-wear and anti-corrosion applications. At the higher temperature up to $550^{\circ}C$ with the increasing ratio of the pulse duration to pulse period up to $50{\mu}s/100{\mu}s$, the nitrided layer, whose growth rate has increased also, has been composed mainly of CrN and $Fe_4N$ phases and has become thick, uniform and nearly crack-free.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.2
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• pp.91-97
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• 2000

The structure and mechanical properties of TiN and TiCN thin films deposited on STD61 steel substrates by the RF-sputtering methods has been studied by using XPS, XRD, micro-hardness tester, scratch tester, and wear-resistance tester. XPS results showed that the TiCN thin film formed with chemical bonding state. The TiN thin films grew with (111) orientation having the lowest strain energy by compressive stress, whereas the TiCN thin films grew with both (111) and (200) orientation, but (200) orientation having the lowest surface energy becomes dominant as carbon contents increase. The pre-etching treatment of substrate did not affect on the preferred orientation of thin films, but it played an important role in improving mechanical properties of thin films such as the hardness, adhesion and wear- resistance. Especially, the TiCN thin films showed the superior wear resistances due to high hardness and low friction coefficient compared with TiN thin films.

• Journal of Environmental Science International
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• v.20 no.7
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• pp.907-917
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• 2011

This study investigated the application of experimental design methodology to optimization of conditions of air-plasma and oxygen-plasma oxidation of N, N-Dimethyl-4-nitrosoaniline (RNO). The reactions of RNO degradation were described as a function of the parameters of voltage ($X_1$), gas flow rate ($X_2$) and initial RNO concentration ($X_3$) and modeled by the use of the central composite design. In pre-test, RNO degradation of the oxygen-plasma was higher than that of the air-plasma though low voltage and gas flow rate. The application of response surface methodology (RSM) yielded the following regression equation, which is an empirical relationship between the RNO removal efficiency and test variables in a coded unit: RNO removal efficiency (%) = $86.06\;+\;5.00X_1\;+\;14.19X_2\;-\;8.08X_3\;+\;3.63X_1X_2\;-\;7.66X_2^2$ (air-plasma); RNO removal efficiency (%) = $88.06\;+\;4.18X_1\;+\;2.25X_2\;-\;4.91X_3\;+\;2.35X_1X_3\;+\;2.66X_1^2\;+\;1.72X_3^2$ (oxygen-plasma). In analysis of the main effect, air flow rate and initial RNO concentration were most important factor on RNO degradation in air-plasma and oxygen-plasma, respectively. Optimized conditions under specified range were obtained for the highest desirability at voltage 152.37 V, 135.49 V voltage and 5.79 L/min, 2.82 L/min gas flow rate and 25.65 mg/L, 34.94 mg/L initial RNO concentration for air-plasma and oxygen-plasma, respectively.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.1
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• pp.48-54
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• 2011

This study was conducted to investigate the effects of dandelion (Teraxacum platycarpum) extracts obtained by only water and with ultrasonification on antioxidative system and lipid metabolism in high cholesterol-fed rats. Five groups of rats were given high cholesterol diets for 8 weeks. The control group received without dandelion extracts and the other four groups received with one of dandelion extracts for 4 weeks respectively ; TP-N-1(100 mg/kg/day of Teraxacum platycarpum water extract), TP-N-2(200 mg/kg/day of Teraxacum platycarpum water extract), TP-S-1(100 mg/kg/day of Teraxacum platycarpum water-ultrasonification extract), TP-S-2(200 mg/kg/day of Teraxacum platycarpum water-ultrasonification extract). The results are summarized as follows; The hepatic and plasma TBARS levels significantly decreased in the dandelion extracts groups compared to those of no treatment group. Especially the group TP-N-2 was comparatively best among those. TP-N-2 groups had significantly higher levels of glutathione peroxidase (GSH-Px) and catalase activities. There was no significant difference between dandelion extracts groups and no treatment group in SOD levels. In plasma triglyceride level, plasma FFA level, TP-S-2 group had significantly lower levels than that of the other groups. In plasma glucose levels, dandelion extracts group were similar to those of normal rats. Plasma total cholesterol levels significantly decreased in the TP-S-2 group compared to those of the other groups. HDL levels were also significantly higher than those of the other groups. Compared with those of no treatment group, dandelion extract groups had significantly higher levels of LDL. In liver total cholesterol level, TP-S-2 groups had significantly lower levels than that of the other groups. Compared with those of no treatment group, dandelion extracts groups had significantly lower levels of liver triglyceride, but especially the TP-S-2 group showed comparatively the best significant effect among those. TBARS, triglyceride, LDL, FFA levels significantly decreased in TP-S-2 groups compared to the other four groups. HDL levels was also significantly higher than the other four groups. According to the above result, it could be suggested that ultrasonic extraction have the upper hand in lipid metabolism and water extraction have the advantage of antioxidative system.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.222-222
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• 2000

PBGA(Plastic Ball Grid Array) is composed of some materials such as PCB(Printed Circuit Board), epoxy molding compound, die attach and so on. Reliability of PBGA package is weak compared with plastic packages. The weak points of reliability are the lower resistance to popcorn cracking, which is induced by moisture absorption in PCB, and the pressure cooker test corrosion, which is the basic problem due to the material characteristics of PCB. Introducing the PCB baking and the plasma treatment cleared the popcorn cracking phenomenon. The PCB baking and plasma treatment reduced the epoxy void by eliminating the source of moisture vaporization during the epoxy curing and enhanced the adhesion between PCB and epoxy. Also, plasma treatment enhanced the wettability of epoxy on PCB. The problem of corrosion is cleared using multi-functional epoxy. This type of EMC(Epoxy Molding Compound) is recommended in package using PCB as a substrate. (Received November 19, 1999)

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.10-13
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• 2010

We studied the effect of $O_2$ plasma treatments on the electrical property of Ti / Al ohmic contacts to N-face n-type GaN. The surface of N-face, n-type GaN has been treated with $O_2$ plasma for 120 s before the deposition of bilayered electrodes, Ti (50 nm) / Al (35 nm), and its contact resistance was compared with that of the reference sample without $O_2$ plasma. As a result, we found that the ohmic contact was reduced from $4.3\;{\times}\;10^{-1}\;{\Omega}cm^2$ to $1.25\;{\times}\;10^{-3}\;{\Omega}cm^2$ by applying $O_2$ plasma on the surface of n-type GaN, which was attributed to the reduction in the Schottky barrier height (SBH), caused by nitrogen vacancies formed during the $O_2$ plasma process.