• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1994년도 추계 학술발표 강연 및 논문 개요집
• /
• pp.170-170
• /
• 1994

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
• /
• pp.80-80
• /
• 1999

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1997년도 한국재료학회 추계학술발표회
• /
• pp.128-128
• /
• 1997

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1993년도 춘계학술발표회
• /
• pp.31-31
• /
• 1993

• Journal of Welding and Joining
• /
• 제32권6호
• /
• pp.35-40
• /
• 2014

The contact tip for gas metal arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. If the contact tip is damaged, it is a cause of lowering the welding productivity due to removal of welding defects and replacement of contact tip. In case of the use of a contact tip for a long time the arc is unstable because the processed hole in the contact tip center is larger, and the variation of aiming position of the welding wire causes a seam tracking error. In this study, gas metal arc welding experiments using contact tip of three different materials were performed. The contact tips with Cu-P, Cu-Cr, and Cu-ODS were used at the experiments, and the welding characteristics by each contact tip were evaluated. After welding contact tip appearance, welding spatter adhesion amount of the nozzle, and weld bead appearance were evaluated. The welding current and welding voltage were measured to verify arc stability during arc welding.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.632-635
• /
• 2004

The purpose of this paper is to investigate the effect of arc current and contact velocity on the erosion of silver-based contact materials to be used in low voltage circuit breakers. The opening velocity during breaking, which is constant, ranges between 2m/s to 6m/s in the 415V $25kA_{rms}$. Contact erosion is evaluated by measuring the mass change of the cathode and anode. The results show that the increase in opening velocity from 2m/s to 6m/s leads to a decrease in the contact erosion. It is shown that the material transfer from one electrode to another depends on the transfer charge and the opening velocity of the contacts. The contact pairs of AgWC/AgCdO are superior to $AgWC/AgSnO_2In_2O_3$ or AgWC/AgC contact pairs in the contact erosion.

• 한국재료학회지
• /
• 제13권7호
• /
• pp.465-472
• /
• 2003

Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au ohmic contacts to n-type InGaAs were investigated for applications to AlGaAs/GaAs HBT emitter ohmic contacts. In the Pd/Ge/Ti/Pt ohmic contact minimum specific contact resistivity of $3.7${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by rapid thermal annealing at $^400{\circ}C$/10 sec. In the Pd/Ge/Ti/Au ohmic contact, minimum specific contact resistivity of $1.1${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by annealing at 40$0^{\circ}C$/10 sec but the ohmic performance was degraded with increasing annealing temperature due to the reaction between the ohmic contact materials and the InGaAs substrate. However, non-spiking planar interface and relatively good ohmic contact (high-$10^{-6}$ /$\Omega$$\textrm{cm}^2$) were maintained after annealing at $450^{\circ}C$/10 sec. Therefore, these thermally stable ohmic contact systems are promising candidates for compound semiconductor devices. RF performance of the AlGaAs/GaAs HBT was also examined by employing the Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au systems as emitter ohmic contacts. Cutoff frequencies were 63.5 ㎓ and 65.0 ㎓, respectively, and maximum oscillation frequencies were 50.5 ㎓ and 51.3 ㎓, respectively, indicating very successful high frequency operations.

• 소성∙가공
• /
• 제20권2호
• /
• pp.99-103
• /
• 2011

Many parameters influence the frictional behavior of steel sheet during stamping. The contact pressure between a die and a sheet during stamping is one of them. Thus, this parameter is investigated for high strength steel (HSS) sheets, which are widely used for auto body panels due to their potential for weight reduction. Since HSS extend the limits of contact pressure for mild steel, the effect of this parameter on friction cannot be ignored. To investigate the influence of contact pressure on the frictional behavior of steel sheets, a flat type of friction test was conducted on three different steel sheets under various contact pressures. For bare steel sheets, the curve representing the relationship between contact pressure and friction coefficient exhibits a U shape. Coated steel sheets show a similar tendency except at low contact pressure. For these materials, when the contact pressure is very low, the friction coefficient slightly increases with pressure before it starts to decrease. The test results show that the effect of contact pressure on frictional behavior of steel sheet is not negligible even for contact pressures that are lower than the strength of HSS sheet.

• 한국재료학회지
• /
• 제14권8호
• /
• pp.573-578
• /
• 2004

Newly developed silicide materials for ULSI should have the appropriate electrical property of low resistant as well as process compatibility in conventional CMOS process. We prepared $NiCoSi_x$ silicides from 15 nm-Co/15 nm-Ni/Si structure and performed contact dry etch process to confirm the dry etch stability and compatibility of $NiCoSi_x$ layers. We dry etched the photoresist/SiO/silicide/silicon patterns with $CF_4\;and\;CHF_3$ gases with varying powers from 100 to 200 W, and pressures from 45 to 65 mTorr, respectively. Polysilicon and silicon active layers without silicide were etched $0\sim316{\AA}$ during over etch time of 3min, while silicon layers with proposed $NiCoSi_x$ silicide were not etched and showed stable surfaces. Our result implies that new $NiCoSi_x$ silicides may replace the conventional silicides due to contact etch process compatibility.

• 치위생과학회지
• /
• 제10권3호
• /
• pp.177-183
• /
• 2010

탄성 고무인상재의 종류인 폴리설파이드(polysulfide), 폴리이써(polyether), 부가중합형 실리콘(addition silicone)에서 점주도(consistency)가 Type III인 인상재를 각각 1종류 선택하여 증류수 $3.3{\mu}l$를 떠뜨려 접촉각을 측정하고, 세 종류의 인상체에 치과용 경석고를 부어 작업모형을 만들고 표면을 관찰하였다. 접촉각 측정은 전자동접촉 각 측정시스템(DM-700, KYOWA, Japan)을 이용하였고 작업모형의 표면관찰은 전계 방사형 주사 전자현미경(JSM-6700F, JEOL Ltd., JAPAN)을 이용하여 다음과 같은 결론을 얻었다. 1) 초기 접촉각의 평균과 표준편차는 부가중합형실리콘, 폴리이써, 폴리설파이드 제품이 각각 $91.3^{\circ}{\pm}20.5$, $90.0^{\circ}{\pm}2.2$, $101.5^{\circ}{\pm}2.3$로 평균값은 유사하게 나타났으나 부가중합형실리콘의 표준편차값에서 큰 차이를 보여줬다. 이는 술자의 술식에 따라 항상 일정한 특성을 보여주지 않는 다는 것이다. 2) 시간이 흐를수록 부가중합형실리콘 제품은 다른 두 종류에 비해 접촉각이 급속히 감소함을 관찰 할 수 있었고, 초기접촉각이 $91.3^{\circ}$이며 25초 후 $29.4^{\circ}$로 급격히 감소했다. 3) 폴리이써 제품은 초기접촉각이 $101.5^{\circ}$에서 25초 후의 접촉각 $90.7^{\circ}$이였고, 폴리설파이드 제품은 초기접촉각이 90.0에서 25초 후의 접촉각 84.2로 변화가 거의 일어나지 않았고 그 각도도 부가중합형실리콘에 비해 컸다. 4) 세 종류의 탄성고무인상재에서 시간이 흐름으로써 관찰된 접촉각은 유의성이 있었다(p<0.001). 5) 작업모형의 표면관찰에서 부가중합형실리콘이 가장 치밀했고, 그 다음 폴리설파이드, 폴리이써 순서였다. 따라서 탄성고무 인상재에 있어서 접착각이 작은 부가중합형 실리콘은 폴리이써나 폴리설파이드 제품에 비해 더 치밀한 작업모형을 얻을 수 있었고 세 종류의 인상재접착각에서 큰 유의성을 보였다. 그러나 부가중형 실리콘은 접촉각의 편차가 커 술자의 주의가 필요한 것으로 나타났고 폴리설파이드 제품과 폴리이써 제품은 20~25초 후 접촉각이 최초 접촉각과 큰 차이를 보이지 않아 소수성 제품으로 인상채득 시 주의가 요망되는 것으로 보여진다. 향후 Vitro 상태에서 인상재에 영향을 미치는 여러가지 요인들에 대한 계속적인 연구의 필요성을 느낀다.