• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.159-160
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• 2007

저온 플라즈마 침탄 처리 후 연속적인 공정으로 저온 플라즈마 질화를 실시하여 내식성과 표면경도를 향상시키는 처리에서 질화처리 시 Ar 가스가 표면특성에 미치는 영향을 조사 하였다. 모든 시편의 경도가 미처리재 보다 약4배 증가하였으며, Ar가스의 양이 증가할수록 N의 침투깊이가 깊어졌다. 전체 경화증의 두께는 거의 일정하였고, 경화층은 모재보다 내식성이 증가되어 단면조직사진에서 밝게 나타났다.

• Journal of Welding and Joining
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• 제15권6호
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• pp.57-65
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• 1997

A study was undertaken to determine the influence of welding variables such as shielding and plasma gases, torch standoff, travel speed and heat input, etc. on the quality of plasma arc welds in Zircaloy-4 sheet, 2mm thick. Effect of shielding gases and their flow rates on the mechanical properties of Zircaloy-4 welds by plasma arc welding were determined in terms of tensile, bardness and bend tests. The microstructure and fracture surface of Zircaloy-4 welds were investigated by optical and scanning electron microscopies. In addition, the causes of porosity and undercut in plasma arc welds of Zircaloy-4 were also investigated. Zircaloy-4 weld bead width and depth by helium shielding gas showed a wider and deeper than those by argon. It was found that Zircaloy-4 welds with shielding gas of helium did dxhibit a little smoother and uniform weld beads than those with shielding gas of argon. It was also found that the optimum gas flow rates for Zircaloy-4 welding were 0.45l/min for plasma gas with Ar and 4.5 - 6 l/min for shielding gas with He. In addition, there was no big difference in the microstructure and fracture surface of the weld metals made by either Ar shielding gas or He shielding gas.

• Journal of Welding and Joining
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• 제27권2호
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• pp.44-50
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• 2009

The characteristics of arc pressure, current density and heat flux distribution are important factors in understanding physical arc phenomena, which will have a marked effect on the penetration, size and shape of a weld in TIG welding. The purpose of this study is to find out the effect of the heat flux on the melting efficiency and penetration shape in TIG welding using the results of the previous investigators. The conclusions obtained permit to draw a proper method which derived the heat flux distributions by arc pressure distribution measurements, but previous researchers calculated heat flux and current distribution with the heat intensity measurements by the calorimetry. Heat flux of Ar gas arc was concentrated at the central part and distributed low from the arc axis to the radial direction, that of He mixing arc was lower than that of Ar gas, and it was wide distributed to radial direction. That showed a similar characteristic with the Nestor's by calorimetry calculated values. Throughout heat flux drawn in this study was discussed melting efficiency and penetration shape on Ar gas and He mixing gas arc.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.25-28
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• 2001

In this paper, we have investigated the effects of gas flow rate, rf power, process pressure and Ar addition on reactive ion etching of InP, InGaAs and InAlAs using Sic14 and Cl$_2$ gases. The etch rates were measured by using a surface profiler. The etched profiles, sidewall roughness, and surface morphology were observed by scanning electron microscopy and by atomic force microscopy. The selective etching of InGaAs to InP and InAlAs was studied by varying the etching parameters. It was found that Cl$_2$ gas is more efficient for the selective etching of InGaAs to InAlAs than SiCl$_4$ gas. The etch selectivity of InGaAs to InAlAs is strongly dependent on the rf power and the process pressure.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.128-128
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• 2010

In this study, we investigated the evolution and reduction of the surface roughness during the high-speed chemical dry thinning process of Si wafers. The direct injection of NO gas into the reactor during the supply of F radicals from NF3 remote plasmas was very effective in increasing the Si thinning rate, due to the NO-induced enhancement of the surface reaction, but resulted in the significant roughening of the thinned Si surface. However, the direct addition of Ar and N2 gas, together with NO gas, decreased the root mean square (RMS) surface roughness of the thinned Si wafer significantly. The process regime for the increasing of the thinning rate and concomitant reduction of the surface roughness was extended at higher Ar gas flow rates. In this way, Si wafer thinning rate as high as $20\;{\mu}m/min$ and very smooth surface roughness was obtained and the mechanical damage of silicon wafer was effectively removed. We also measured die fracture strength of thinned Si wafer in order to understand the effect of chemical dry thinning on removal of mechanical damage generated during mechanical grinding. The die fracture strength of the thinned Si wafers was measured using 3-point bending test and compared. The results indicated that chemical dry thinning with reduced surface roughness and removal of mechanical damage increased the die fracture strength of the thinned Si wafer.

• 한국기계가공학회지
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• 제12권2호
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• pp.49-54
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• 2013

Recently welding of aluminum material is actively carried out to make lightweight in the fields of LNG vessels, aircraft, chemical plants, etc. To obtain high strength, hardness and elongation, elements such as manganese, zinc, silicon, etc should be added in aluminum alloy, which has been improved on the mechanical properties like precipitation hardening, age hardening, loosening, corrosion resistance acid resistance. Ar gas is used as a shielding gas of MIG welding for aluminum, also $N_2$, $O_2$, $CO_2$, $H_2$ etc can be added depending on the composition of the alloy. In this study, Ar + $O_2$, Ar, and He were used for welding, hardness, penetration status and changes in composition of penetrated parts were compared and analyzed. This made it possible to know the status and changes of the process in the penetrated parts depending on used gas throughout this study.

• 한국표면공학회지
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• 제38권5호
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• pp.202-206
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• 2005

Nitriding treatments were conducted on tool steel (SKD 61) at a temperature of $500^{\circ}C$ for 5 hr using high vacuum direct current (DC) plasma, with ammonia and argon as source gases. The structural and compositional changes produced in the nitrided layers by applying different ratios of Ar to $NH_{3}\;(n_{Ar}/n_{NH3}) were investigated using glancing x-ray diffraction (GXRD), optical microscopy, atomic force microscopy (AFM), micro-Vickers hardness testing, and pin-on-disc type tribometer. Nitriding case depths of around of $50{\mu}m$ were produced, varying slightly with different ratios of $n_{Ar}/n_{NH3}. It was found that the specimen surface hardness was 1150 Hv with $n_{Ar}/n_{NH3}=1, increasing to a maximum value of 1500 Hv with $n_{Ar}/n_{NH3}=5. With a further increase in ratio to $n_{Ar}/n_{NH3}=10, the surface hardness of the specimen reduced slightly to a value of 1370 Hv. These phenomena were caused by changes of the crystallographic structure of the nitride layers, i.e the $\gamma'-Fe_{4}N$ phase only was observed in the sample treated with $n_{Ar}/n_{NH3}$=1, and the intensity of the $\gamma'-Fe_{4}N$ phase were reduced but new phase of $\varepsilon'-Fe_{3}N$, which was known as a high hardness, with increasing $n_{Ar}/n_{NH3}. Also, the relative weight loss of counterface of the pin-on-disc with unnitrided steel was 0.2. And that of nitrided steel at a gas mixture ($n_{Ar}/n_{NH3}) of 1, 5, 7, and 10 was 0.4, 0.7, 0.6, and 0.5 mg, respectively. This means that the wear resistance of the nitrided samples could be increased by a factor of 2 at least than that of unnitrided steel.

• 자원리싸이클링
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• 제25권3호
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• pp.49-54
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• 2016

본 연구에서는, 아크 플라즈마 정련을 이용하여 지르콘샌드($ZrSiO_4$)를 지르코니아($ZrO_2$)와 실리카($SiO_2$)로 분리하였다. 실리카를 마이크로웨이브 침출을 통해 제거하고 고순도의 지르코니아를 얻었다. 플라즈마 퓨전은 두 가지 공정을 순차적으로 진행하였다. Ar 100% 분위기에서 환원 공정을 거친 후, Ar-$H_2$ 혼합 가스를 통해 정련과정을 거쳤다. 진공 챔버 내에서 냉각 후 지르코니아와 실리카로 이루어진 고상을 얻었다. 마이크로웨이브 침출을 위해 $240^{\circ}C$, 20% 황산용액을 사용하였다. 분석 결과 고순도(98.6%)의 지르코니아를 얻을 수 있었다.

• 한국산학기술학회논문지
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• 제15권10호
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• pp.5933-5938
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• 2014

본 연구에서는 Atos 60의 시험편에 혼합가스의 변화에 따른 FCA용접을 하였고, 용접특성 분석 위하여 용접공정상의 실시간 모니터링 시스템과 용접 후 기계적 성질을 평가 하였다. Ar 80%+$CO_2$ 20% 혼합하고 낮은 속도로 용접한 경우 가장 미려한 비드와 스패터 발생이 적게 나타났으며, 반면 $CO_2$ 100%인 경우 스패터가 많이 발생하는 것을 확인하였다. 정상단락이 발생하는 저전류 영역으로 혼합가스의 사용에 대한 스패터 발생을 확인 할수 있는 조건이며, $CO_2$ 100%인 경우 각층의 단락율은 약 2배 이상 높았고, Peak의 분포가 많은 아크의 불안정 상태로 나타났다. 인장시험결과 Ar 80%+$CO_2$ 20%, Ar 90%+$CO_2$ 10%, $CO_2$ 100%의 항복강도는 각각 511MPa, 507MPa, 469MPa 이었으며, $CO_2$ 100%의 항복강도 보다 각각 약 8.9% 8.1% 향상되었다. 인장강도는 각각 622MPa, 609MPa, 581MPa로 $CO_2$ 100%의 인장강도 보다 각각 약 7.0%, 4.8% 향상되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.127-128
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• 2009

CCP방식의 식각에 있어서 CF4/O2 Plasma Etch에 Ar을 첨가함으로써 Etch특성이 어떻게 변화하는지를 조사하였다. FE-SEM를 이용하여 Etch Profile를 측정하였다. 또한 Elipsometer와 Nanospec을 이용하여 Etch rate를 측정하였다. Ar의 비율이 전체의 47%정도를 차지하였을 때까지 Etch Profile이 향상되었다가 그이후로는 다시 감소하는 것을 볼 수 있었다. Ar을 첨가할수록 etch rate은 계속 향상되었다. Ar을 첨가하는 것은 물리적인 식각으로 반응하여 Etch rate의 향상과 적정량의 Ar을 첨가했을 때 Etch profile이 향상되는 결과를 얻었다.