Effects of Ar gas Composition on the Characteristics of Surface Layers Formed on AISI 316L Stainless Steel During Low-Temperature Plasma Nitriding after Low-Temperature Plasma carburizing

이인섭 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5

A 2-step low-temperature plasma process (the combined carburizing and post- nitriding) increases both the surface hardness and the thickness of the hardened layer and the corrosion resistance compared to individually processed low-temperature nitriding and low-temperature carburizing techniques. The 2-step low-temperature plasma process was carried out to improve both the surface hardness and the corrosion resistance of AISI 316L stainless steel. The influence of the Ar gas level in the atmosphere during the nitriding step on the surface properties was investigated. The expanded austenite (rN) was formed on all the treated surface. The thickness of rN was increased up to about 15 μm, and the thickness of the entire hardened layer was determined to be about 40 μm. The surface hardness reached 1200 HV0.1, which is about 5 times higher than that of the untreated sample (250 HV0.1). The thickness of the rN layer increased with increasing Ar gas content in the atmosphere. The corrosion resistance in the austenitic stainless steel processed by using the 2-step low temperature plasma was also much enhanced compared to that in the untreated austenitic stainless steel due to the high concentration of N on the surface. A 2-step low-temperature plasma process (the combined carburizing and post- nitriding) increases both the surface hardness and the thickness of the hardened layer and the corrosion resistance compared to individually processed low-temperature nitriding and low-temperature carburizing techniques. The 2-step low-temperature plasma process was carried out to improve both the surface hardness and the corrosion resistance of AISI 316L stainless steel. The influence of the Ar gas level in the atmosphere during the nitriding step on the surface properties was investigated. The expanded austenite (rN) was formed on all the treated surface. The thickness of rN was increased up to about 15 μm, and the thickness of the entire hardened layer was determined to be about 40 μm. The surface hardness reached 1200 HV0.1, which is about 5 times higher than that of the untreated sample (250 HV0.1). The thickness of the rN layer increased with increasing Ar gas content in the atmosphere. The corrosion resistance in the austenitic stainless steel processed by using the 2-step low temperature plasma was also much enhanced compared to that in the untreated austenitic stainless steel due to the high concentration of N on the surface.

Evaluating Antistatic Performance of Plasma-treated Polyester

Kan, C.W. The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.6

Use of low temperature plasma treatment has been attempted in the textile industry and there the has been some success in the dyeing and finishing processes. In this paper, an attempt was made to apply low temperature plasma treatment to improve the antistatic property of polyester fabric. The polyester fabrics were treated under different conditions with low temperature plasma. An orthogonal array testing strategy was employed for obtaining the optimum treatment condition. After low temperature plasma treatment, the polyester fabrics were evaluated with different characterization methods, Under the observation of scanning electron microscope, the surface structure of the polyester fabric treated by low temperature plasma was found to be seriously altered which provided more capacity for polyester to capture moisture and hence increased the static charges dissipation. The relationship between moisture content and half-life decay time for static charges was studied and the results showed that the increase in moisture content would result in shortening of the time for static charges dissipation. Moreover, the antistatic property of the low temperature plasma treated polyester fabric was greatly improved. In addition, the antistatic property of the polyester fabric treated by low temperature plasma was compared with that of the polyester fabric treated with a commercial antistatic finishing agent.

Evaluation of the Promotion for Antibacterial Activity on Cibotium barometz J. Smith with Low-Temperature Plasma from Electric Currents and Magnetic Fields

Seoul-Hee Nam,Man-Seok Han,김규천 한국자기학회 2022 Journal of Magnetics Vol.27 No.4

Many studies have been conducted in pursuit of health and safety. This study aims to suggest a preventive and therapeutic plan to address dental caries by confirming the antibacterial effect of Cibotium barometz J. Smith (Cibotium barometz J. S), a natural material, on Streptococcus mutans (S. mutans), a type of bacteria that can cause dental carries, and to maximize the efficiency of antibacterial activity by applying low-temperature plasma from electric currents and magnetic fields. Low-temperature plasma can be applied to living tissue without thermal damage, and the composition of plasma is diverse, so the application field is increasing. Cibotium barometz J. S extract was treated with S. mutans diluted to 1 × 105 CFUs/mL from low concentration (0.01 mg/mL) to high concentration (45 mg/mL) for 6 and 24 hours. CFUs (colony forming units) were counted for the corresponding time, and lowtemperature plasma was used in combination to maximize antibacterial effect. The higher the concentration of Cibotium barometz J. S extract, the higher the death rate was, and antibacterial activity increased when combined with low-temperature plasma, compared to using Cibotium barometz J. S extract alone. The application of low-temperature plasma improves the penetration of Cibotium barometz J. S extract safely and effectively to suppress the occurrence of dental caries, and has good antibacterial effect. Therefore, low-temperature plasma is considered excellent in promoting oral health.

운동심리학 : 상온 및 저온 환경의 지속적 운동시 BCAA 추가섭취에 따른 생리적 반응의 비교

김홍수(KimHong-Soo),김기진(KimKi-Jin) 한국체육학회 2003 한국체육학회지 Vol.42 No.2

The purpose of this study was to investigate the possibilities of improving endurance exercise capacity in low temperature through the supplementation of branched-chain amino acid(BCAA) by analyzing the effect of BCAA supplementation on physiological responses during submaximal prolonged exercise between thermoneutral and low temperature. Six male high school long-distance runners participated in the experiment as subjects and were exposed to thermoneytral(22±1℃) and low temperature (5±1℃) conditions with relative humidity of 60±5% for 60 min. Each subject performed 90 min, endurance exercise on the fixed cycle ergometer at 60%VO₂max in two treatment conditions, with the supplementation placebo and BCAA. In the BCAA condition, the subject was supplemented with 200㎖ of BCAA solution prepared by dissolving 200㎎/㎏ in weight of BCAA in 400㎖ of pure water at both 45 min. and 15 min. prior. to exercise. In the placebo condition, placebo(water) was used instead of BCAA in preparing the oral supplement. During the experiment, physiological variables relation to endurance capacity were measured. Although rectal temperature was high in the thermoneutral condition than the low temperature, the differed between BCAA and placebo conditions was not significant. In terms of test session, it decreased after the BCAA supplementation but increased with the exercise. It remained higher than prior to BCAA supplementation at 30 min. after the end of exercise. Heart rate was higher in the thermoneutral condition than the low temperature, but the difference between BCAA and placebo conditions was not significant. It increased with exercise in both temperature conditions, and in the thermoneutral condition it remained higher than prior to BCAA supplementation at 30 min. after the end of exercise. Blood lactate concentration was not affected by treatment. In the thermoneutral condition it increased from the exercise onset for 30 min, and decreased from 90 min. exercise. In the low temperature, however, it increased at 30 min exercise compared to that prior to supplementation and remained in the steady state after that period. While plasma ammonia concentration was not different between temperature conditions, it was higher in the BCAA condition than placebo. In the BCAA condition, it increased during the exercise. In the placebo condition, however, it increased during the exercise but decreased to the level at 30 min exercise at 30 min. after the end of exercise. Taken together, although the environmental temperature affect to the endurance capacity during submaximal prolonged exercise, BCAA supplementation during prolonged exercise in low temperature does not seem to have the possibility of improving endurance exercise capacity and metabolism

대기압 저온 플라즈마 처리에 의한 폴리이미드의 친수화 효과

조중희,강방권,김경수,최병규,김세훈,최원열,Cho, J.H.,Kang, B.K.,Kim, K.S.,Choi, B.K.,Kim, S.H.,Choi, W.Y. 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.2

Atmospheric low-temperature plasma was produced using dielectric barrier discharge (DBD) plate-type plasma reactor and high frequency of 13.56 Hz. The surfaces of polyimide films for insulating and packaging materials were treated by the atmospheric low-temperature plasma. The contact angle of 67$^{\circ}$ was observed before the plasma treatment. The contact angle was decreased with deceasing the velocity of plasma treatment. In case of oxygen content of 0.2 %, electrode gap of 2 mm, the velocity of plasma treatment of 20 mm/sec, and input power of 400 W, the minimum contact angle of 13$^{\circ}$ was observed. The chemical characteristics of polyimide film after the plama treatment were investigated using X-ray photoelectron spectroscopy (XPS), and new carboxyl group bond was observed. The surfaces of polyimide films were changed into hydrophilic by the atmospheric low-temperature plasma. The polyimide films having hydrophilic surface will be very useful as a packaging and insulating materials in electronic devices.

3차원 소자 제작을 위한 ICP Type Remote PEALD를 이용한 저온(< 300℃) SiO₂ 및 SiON 박막 공정

김대현,박태주,Kim, Dae Hyun,Park, Tea Joo 한국반도체디스플레이기술학회 2019 반도체디스플레이기술학회지 Vol.18 No.2

Direct plasma-enhanced atomic layer deposition (PEALD) are widely used for $SiO_2$ and SiON thin film process in current semiconductor industry. However, this exhibits poor step coverage for three-dimensional device structure due directionality of plasma species as well as plasma damage on the substrate. In this study, to overcome this issue, low temperature (< $300^{\circ}C$) $SiO_2$ and SiON thin film processes were studied using inductively coupled plasma (ICP) type remote PEALD with various reactant gases such as $O_2$, $H_2O$, $N_2$ and $NH_3$. It was confirmed that the interfacial properties such as fixed charge density and charge trapping behavior of thin films were considerably improved by hydrogen species in $H_2O$ and $NH_3$ plasma compared to the films grown with $O_2$ and $N_2$ plasma. Furthermore, the leakage current density of the thin films was suppressed for same reason.

Influence of Temperature and Time on Low-Temperature Plasma Nitrocarburizing of AISI 304L Austenitic Stainless Steel

이인섭 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.3

The major drive for the applications of low-temperature plasma treatment in nitrocarburizing of austenitic stainless steels lies in improved surface hardness without degraded corrosion resistance. The low-temperature plasma nitrocarburizing was performed in a gas mixture of N2, H2 and a carbon-containing gas such as CH4. The in uence of the processing temperature (380-430℃) and time (4-20 h) on the surface properties of the nitrocarburized layer was investigated. The resultant nitrocarburized layer was a dual-layer structure, which was comprised of a N-enriched layer (γN) with a high nitrogen content on top of a C-enriched layer (γC) with a high carbon content, leading to a significant increase in surface hardness and corrosion resistance. Chromium nitride was formed in the N-enriched layer only for the specimen treated at 430℃. The surface hardness and the layer thickness increased up to about 1200 HV0.01 and 15μm with increasing temperature and time, respectively. No loss in corrosion resistance was observed, except for the specimen treated at 430℃. The major drive for the applications of low-temperature plasma treatment in nitrocarburizing of austenitic stainless steels lies in improved surface hardness without degraded corrosion resistance. The low-temperature plasma nitrocarburizing was performed in a gas mixture of N2, H2 and a carbon-containing gas such as CH4. The in uence of the processing temperature (380-430℃) and time (4-20 h) on the surface properties of the nitrocarburized layer was investigated. The resultant nitrocarburized layer was a dual-layer structure, which was comprised of a N-enriched layer (γN) with a high nitrogen content on top of a C-enriched layer (γC) with a high carbon content, leading to a significant increase in surface hardness and corrosion resistance. Chromium nitride was formed in the N-enriched layer only for the specimen treated at 430℃. The surface hardness and the layer thickness increased up to about 1200 HV0.01 and 15μm with increasing temperature and time, respectively. No loss in corrosion resistance was observed, except for the specimen treated at 430℃.

UV photon assist ionization for low temperature plasma

Chae, S.H.,Seo, S.H.,Chang, H.Y. Elsevier 2006 CURRENT APPLIED PHYSICS Vol.6 No.2

<P><B>Abstract</B></P><P>A new type plasma source has been developed for the generation of low temperature plasma. The plasma generation process consists of two steps, the generation of metastable neutral gas by injecting a low energy electron beam (the thermionic source) and the ionization of the metastable neutral gas by application of a UV light source. The key characteristic of this plasma source is the capability of producing extremely low temperature plasma.</P><P>In the experiment, the filament heating current is 6.5A and the electron acceleration voltage varies from 16V to 25V. Plasma parameters are measured by a single Langmuir probe. The plasma density increases 100%, from 4.5×10<SUP>9</SUP>cm<SUP>−3</SUP> to 9.8×10<SUP>9</SUP>cm<SUP>−3</SUP> in Ar 30mTorr when the neutrals excited by the e-beam are exposed to the UV light. However, the electron temperature is still low, i.e., ∼0.5eV. A similar result is observed in the case of Xe.</P>

Optical emission spectroscopy and collisional-radiative modeling for low temperature Ar plasmas

Chai, Kil-Byoung,Kwon, Duck-Hee Elsevier 2019 Journal of quantitative spectroscopy & radiative t Vol.227 No.-

<P><B>Abstract</B></P> <P>Reliability of electron temperature and density diagnostics by an optical emission spectroscopy and a collisional radiative modeling is investigated by being compared with a Langmuir probe diagnostics for capacitively-coupled and inductively-coupled Ar plasmas in the ranges of electron temperature 1.2–2.2 eV and density 4.0 × <SUP> 10 9 </SUP> − 8.0 × <SUP> 10 11 </SUP> cm <SUP> − 3 </SUP> . Particular attention has been paid to radiation trapping and electron energy distribution function (EEDF) regarding the modeling. It is found that the two-temperature EEDF model gives better agreement of electron temperature diagnostics with the Langmuir probe measurement for non-Maxwellian plasma. The radiation trapping with an escape factor for finite size cylinder geometry reduces the discrepancy between the modeled and measured spectral line intensities compared to an escape factor for plane parallel geometry, specially for the optically thick 811.5 nm transition to the metastable level whose population depends on the diffusion rate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Diagnostics of electron temperature and density for low temperature Ar plasma by an optical emission spectroscopy combined with a collisional-radiative (CR) model has been investigated and compared with a Langmuir probe diagnostics. </LI> <LI> The CR model considers two-temperature electron energy distribution function and an escape factor for finite cylinder geometry in a capacitively-coupled plasma and an inductively-coupled plasma. </LI> <LI> Two-temperature EEDF model works well with the non-Maxwellian plasmas and the finite-cylinder escape factor gives plasma emission spectra close to the measured spectra. </LI> </UL> </P>

Production of pure hydrogen from methane by low temperature plasma processing

조동련,Hae-Na Kim,Minguen Lee,Eun-Kyung Choi 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12

Production of pure hydrogen from methane by a low temperature plasma process coupled with catalytic reaction was investigated. In low temperature plasma, methane molecules were converted to thin solid films and hydrogen. The conversion of methane and the hydrogen yield depended on the flow rate of methane and the discharge power for the low temperature plasma process. They increased as the flow rate decreased and the discharge power increased. A conversion as high as 87.4% and hydrogen yield as high as 67% could be obtained, but the purity of the hydrogen was less than 90%. The purity could be increased to 100% by coupling the low temperature plasma process with a catalytic reaction using a plasma-catalyst hybrid system.