• Journal of Welding and Joining
• /
• 제20권6호
• /
• pp.762-768
• /
• 2002

In this study, the low temperature toughness was evaluated by using the instrumented Charpy impact testing procedures for A15083-O aluminum alloy used in the LNG carrying and storage tank. The specimens were GMA(Gas Metal Arc) welded with four different mixing shield gas ratios (Ar100%+He0%, Ar67%+He33%, Ar50%, and Ar33%+He67%), and tested at four different temperatures(+25, -30, -85, and $-196^{\circ}C$) in order to investigate the influence of the mixing shielding gas ratio and the low temperature. The specimens were divided into base metal, weld metal, fusion line, and HAZ specimen according to the notch position. From experiment the maximum load and displacement were shown the highest and He lowest at $-196^{\circ}C$ than the other test temperatures. The absorption energy of weld metal notched specimens was not nearly depends on test temperature and mixing shield gas ratio because the casting structure was formed in weld metal zone by melting welding wire. On the other hand, the others specimens was shown that the lower temperature, the higher absorption energy slightly up to $-85^{\circ}C$ but the energy was decreased so mush at $-196^{\circ}C$.

• 한국세라믹학회지
• /
• 제31권8호
• /
• pp.886-892
• /
• 1994

Structural and electrical properties of BaTiO3 thin films deposited on Pt/SiO2/Si substrates by RF magnetron sputtering method have been investigated. Crystallization behavior and electrical properties were studied for the films deposited under various sputtering gas compositions (Ar+O2 gas mixture) and substrate temperatures. All the films deposited above 50$0^{\circ}C$ were all crystallized and their preferred orientation changed from (001) to (111) with the addition of oxygen gas. The dielectric constant of films deposited in pure argon was about 110 and showed little dependence on the substrate temperature. But that was increased as the ratio of O2/Ar increased and its substrate temperature dependence was discernible. The highest dielectric constant reached to 550. In addition, the films deposited in mixed gas showed stable dielectric properties against the frequency and temperature.

• 한국레이저가공학회지
• /
• 제6권1호
• /
• pp.25-31
• /
• 2003

5052 aluminum alloy sheets of 2mm thickness were butt welded using a continuous wave Nd:YAG laser with and without Ar shielding gas. Vickers hardness, transverse-weld tensile and bulge tests were carried out to investigate the effect of Ar shielding gas on the mechanical properties and formability of laser welds. Porosity in the weld metals was investigated using an optical microscope. Mechanical properties and formability of 5052 aluminum alloy laser welds were degraded compared to those of base metal. However, those properties were improved due to the reduced size and number of porosity when Ar shielding gas was used.

• 한국레이저가공학회지
• /
• 제6권2호
• /
• pp.19-26
• /
• 2003

6061 aluminum alloy sheets were I-square butt welded using a continuous wave Nd:YAC laser. Heat inputs were varied from 54.6 to 80 J/mm for butt welding using different sets of the laser power and the weld speed. I-square butt welds were also made with and without Ar shielding gas. The effect of Ar shielding gas and heat input on the mechanical properties and formability was investigated using Vickers hardness, transverse-weld tensile and bulge test. Porosity on the weld beads and sections and hot crack on the fracture surfaces of transverse-weld tensile test specimens were investigated using optical and scanning electron microscopy The experimental results showed that mechanical properties and formability of 6061 aluminum alloy laser welds were degraded compared to those of base metal. Mechanical properties and formability of 6061 aluminum alloy laser welds were not substantially changed when Ar shielding gas was supplied or heat inputs were varied.

• 한국레이저가공학회지
• /
• 제9권1호
• /
• pp.25-29
• /
• 2006

This study aimed to investigate the change of mechanical properties with the rolling direction and shielding condition during laser welding of AZ31 magnesium alloy. AZ31 magnesium alloy sheets of 1mm thickness were welded using a continuous wave Nd:YAG laser with and without Ar shielding gas. The effect of Ar shielding gas and rolling direction on the mechanical properties were investigated using Vickers hardness, transverse-weld tensile. Porosity in the weld metals was investigated using an optical microscope. The experimental results showed that mechanical properties of AZ31 magnesium alloy laser welds were upgraded compared to those of base metal. Mechanical properties of AZ31 magnesium alloy laser welds were not substantially changed when Ar shielding gas was supplied.

• 한국표면공학회지
• /
• 제29권5호
• /
• pp.424-429
• /
• 1996

Thin films of Ti-Ni alloy were formed by sputtering under various Ar gas pressures and r. f. powers to investigate the optimum sputtering conditions and to demonstrate their shape memory effect. The composition and structure of the films were examined by electron micro-probe analysis and scanning electron microscope. These films were annealed in order to crystallize them. The mechanical property of the annealed films was evaluated by a conventional bending test. The transformation tmeperatures were determined by differential scanning calorimetry. The shape memory behaviour was examined quantiatatively by changing in sample temperature under various constant loads. It was found that the Ar gas pressure had a critical effect on the mechanical property of the thin film,s although the r.f. power also affected it. The films formed at a high Ar gas pressure were too brittle to be bent successfully. However, the films formed at a low Ar gas pressur could be bent and their shape memory behavior was found to be comparable with that of bulk Ti-Ni alloys.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
• /
• pp.92-95
• /
• 2003

In this paper, the emission properties of electrodeless fluorescent lamp were discussed using the inductively coupled plasma. To transmit the electromagnetic energy into the chamber, a RF power of 13.56MHz was applied to the antenna and considering the Ar gas pressure and the RF electric power change, the emission spectrum, Ar-I line, luminance were investigated. At this time the input parameter for ICP RF plasma, Ar gas pressure and RF power were applied in the range of 10~60m Torr, 10~300W respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
• /
• pp.17-21
• /
• 2000

A Study on the electron energy distribution function in $SF_6+Ar$ mixtures gas used by MCS-BE algorithm, the electron swam parameters in the 0.5% and 0.2% $SF_6+Ar$ mixtures are measured by time of flight method over the E/N(Td) range from 30 to 300(Td). A two-term approximation of the Boltzmann equation analysis and Monte Carlo simulation have been also used to study electron transport coefficients. The electron energy distribution function has been analysed in $SF_6$ gas and $SF_6+Ar$ mixtures at E/N : 200(Td) for a case of the equilibrium region in the mean electron energy. The measured results and the calculated results have been compared each other.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권1호
• /
• pp.20-23
• /
• 2004

In this paper, the emission properties of electrodeless fluorescent lamp were discussed using the inductively coupled plasma. To transmit the electromagnetic energy into the chamber, a RF power of 13.56 [MHz] was applied to the antenna and considering the Ar gas pressure and the RF electric power change, the emission spectrum, Ar I line, luminance were investigated. At this time, the input parameter for ICP RF plasma, Ar gas pressure and RF power were applied in the range of 10∼60 [mTorr], 10∼300 [W], respectively. From emission intensity and lumnance intensity results, the mode transition from E-mode to H-mode was observed. This implies that this method can be used to find an optimal RF power for efficient light illumination in an electrodeless fluorescent lamp.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 C
• /
• pp.1695-1697
• /
• 2003

In this paper the emission properties of electrodeless fluorescent lamp were discussed using the inductively coupled plasma. To transmit the electromagnetic energy into the chamber a RF power of 13.56MHz was appied to the antenna and considering the Ar gas pressure and the RF electric power change, the emission spectrum, Ar-I line, luminance were investigated. At this time the input parameter for ICP RF plasma, Ar gas pressure and RF power were applied in the range of 10${\sim}$60m Torr, 10${\sim}$300W respectively.