• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
• /
• pp.275-280
• /
• 1997

We have investigated the deposition characteristics of (Ni0.8Fe0.2)20Ag80 thin films as a function of chamber pressure and nitrogen flow rate with scanning electron microscopy(SEM), atomic force microscopy(AFM), XRD and $\alpha$-step. The deposition rate of these film is decreased with increasing the chamber pressure and the nitrogen flow rate. With raising the chamber pressure, the growth mode of thin film is changed from island growth to columnar one, which is probably due to energy of atom. Contrary, the nitrogen flow rate is raised, growth mode is changed from columnar to island one. According to the XRD patterns, the preferred orientation is inhibited as the nitrogen flow rate is kept above 10 sccm, but that is nearly independent on the chamber pressure. When the chamber pressure decrease or the nitrogen flow rate increase, phase separation into permoally and silver is occured.

• 한국세라믹학회지
• /
• 제21권1호
• /
• pp.51-59
• /
• 1984

In this paper mechanical properties of reaction-bonded silicon nitride are studied with the variation of initial nitrogen partial pressure. At 1, 25$0^{\circ}C$ the amount of nitridation and the nucleation of nitride increase linearly with the nitrogen partial pressure increase. After the nitridation is completed the density of nitride and modulus of rupture at room temperature are increased with the amount of nitridation. When the partial pressure of nitrogen is 0.5 atm the specimen show the optimum properties that is the highest density of nitride and modulus of rupture. Also the microstructure of $\alpha$-matte is deveoped very well at that pressure of nitrogen which contributes to the strength development of specimen. It is shown that with proper control of initial partial pressure of nitrogen high strength silicon nitride body can be manufactured for dynamic applications.

• 한국결정성장학회지
• /
• 제26권3호
• /
• pp.121-125
• /
• 2016

The effect of temperature and pressure in the nitrogen ambient furnace on bulk micro defect (BMD) and denuded zone (Dz) is experimentally investigated. It is found that as pressure increases, Dz depth increases with a small decrease of BMD density in the range of temperature, $100{\sim}300^{\circ}C$. BMD density with hot isostatic pressure treatment (HIP) at temperature of $850^{\circ}C$ is higher than that without HIP while Dz depth is lower due to much higher BMD density. As the pressure increases, BMD density is increased and saturated to a critical value, and Dz depth increases even if BMD density is saturated. The concentration of nitrogen increases near the surface with increasing pressure, and the peak of the concentration moves closer to the surface. The nitrogen is gathered near the surface, and does not become in-diffusion to the bulk of the wafer. The silicon nitride layer near the surface prevents to inject the additional nitrogen into the bulk of the wafer across the layer. The nitrogen does not affect the formation of BMD. On the other hand, the oxygen is moved into the bulk of the wafer by increasing pressure. Dz depth from the surface is extended into the bulk because the nuclei of BMD move into the bulk of the wafer.

• 대한기계학회논문집B
• /
• 제33권3호
• /
• pp.207-214
• /
• 2009

Crossover of nitrogen from cathode to anode is inevitable in typical membranes used in PEM fuel cells. This crossovered nitrogen normally accumulates in the hydrogen recirculation system at anode side channels. Excessive buildup of nitrogen in the anode side lowers the relative hydrogen concentration and finally affects the performance of fuel cell stack. So it is very important to analysis the nitrogen gas crossover at various operating conditions. In this study, characterization of nitrogen gas crossover in PEM fuel cell stack was investigated. The mass spectroscopy (MS) has been applied to measure the amount of the crossovered nitrogen gas at the anode exit. Results show that nitrogen gas crossover rate was affected by current density, anode and cathode stoichiometric ratio and operating pressure. Current density, anode stoichiometric ratio and anode operating pressure do not affect nitrogen crossover rate but anode exit concentration of nitrogen. Cathode pressure and stoichiometric ratio largely affect the nitrogen crossover rate.

• 조명전기설비학회논문지
• /
• 제27권2호
• /
• pp.77-83
• /
• 2013

In this study, we aimed to determine the optical properties of the plasma used for the dry cleaning method. The optical properties of the atmospheric pressure plasma device were measured through the degree of ionization of hydrogen or nitrogen gas by ionized atmospheric gas. The degree of ionization of hydrogen or nitrogen is closely associated with surface modification. We observed through our experiments that argon gas, an atmospheric gas, caused an increase in the ionization of nitrogen gas, which has similar ionization energy. This type of increase in nitrogen gas ions is believed to affect surface modification. The results of our study show that the pressure of argon gas and the partial pressure of argon and nitrogen gases lead to different results. This important result shows that argon ions can affect the ionization of nitrogen gas.

• 한국초전도ㆍ저온공학회논문지
• /
• 제4권2호
• /
• pp.1-4
• /
• 2002

Electrical properties of liquid nitrogen ($LN_2$) and gaseous nitrogen($GN_2$) have become of great interest again since the discovery of high temperature superconductors . It is very important from a point of superconducting apparatus protection to elucidate breakdown characteristics in $LN_2$ and $GN_2$ at atmospheric and pressurized conditions Therefore. this paper studies the effect of pressure on the breakdown characteristics in $LN_2$ and $GN_2$. Af high voltage is applied to electrode system with uniform and non-unform field in various gap length. And Breakdown voltages of $LN_2$ and $GN_2$ are investigated under AC voltage for Pressure ranging from 0 and 0.5 MPa. This research presented basis information of electrical insulation design for liquid nitrogen immersed HTS power apparatus.

• 한국안전학회지
• /
• 제25권6호
• /
• pp.109-114
• /
• 2010

Water mist fire suppression system is environmental system and needs a flange pump to jet water. In this research, high pressure Nitrogen cylinder is used as a pressurizing source instead of flange pump, and also we tried to find the possibility of using compressed Nitrogen as a fire suppression agent. As a result, it was possible to design water mist fire suppression system with Nitrogen cylinder and suppress oil fire effectively. With DK1.58 nozzle, the optimum Nitrogen pressure was 80bar and the pressure was stable during water mist spray. However, jet of Nitrogen was not effective fire suppression agent when it was dually used with water mist because water mist has blown away, and it is efficient way to use compressed Nitrogen as a pressurizing source only.

• 한국정밀공학회지
• /
• 제25권7호
• /
• pp.124-130
• /
• 2008

The effect of nitrogen gas pressure in arc ion plating on surface properties of the TiN-coated high speed steel(SKH51) is presented in this paper. The surface roughness, micro-particle, micro-hardness, coated thickness, atomic distribution of TiN, and adhesion strength are measured fur various nitrogen gas pressures. It has been shown that the nitrogen gas pressure has a considerable effect on the surface roughness, adhesion strength, atomic distribution of TiN, and surface deposition of TiN of the high speed steels but that it has little influence on the micro-hardness and coated thickness.

• 동력기계공학회지
• /
• 제20권5호
• /
• pp.14-19
• /
• 2016

This study is about the effect of nitrogen gas pressures during manufacturing process on the mechanical properties of composite materials. $TiO_2$/epoxy resin nanocomposites and carbon fiber reinforced epoxy resin(CFRP) composites were fabricated under various nitrogen gas pressures. Tensile strength test, vicker's hardness test and fracture surface observation were carried out to investigate the effect of nitrogen gas pressure. As a result, the tensile strength of nanocomposite and CFRP composites showed clearly increasing tendency by a change in the nitrogen gas pressure up to 3.0 atm and then the tensile strength decreased a little. However, the vicker's hardness of $TiO_2$/epoxy nanocomposites showed same hardness values regardless of the nitrogen gas pressures.

• 항공우주시스템공학회지
• /
• 제14권5호
• /
• pp.26-32
• /
• 2020

본 연구에서는 액체로켓 연소기의 연소 불안정 모사를 위해 극저온 유체인 액체질소를 공급하는 설비를 구축하였다. 가압 및 공급 성능을 예측하였으며 실험을 통하여 검증하였다. 액체질소 공급 시스템은 가압식 공급 시스템으로 구성하였으며, 가압제 압력 조정은 돔 레귤레이터를 사용하였다. 액체질소 공급 유량 제어는 캐비테이션 벤추리를 사용하였으며, 액체 질소 공급 조건은 초당 유량 2.55 kg/s, 벤추리 입구 압력은 100 bar 이상이다. 초기 실험 결과 예측된 가압제의 양이 충분히 공급되지 못하여, 탱크압력 강하가 발생해 목표 유량을 공급하지 못하였다. 구축된 설비의 변경 및 보완을 통하여, 최종적으로 목표 유량 공급에 성공하여 극저온 액체질소 공급 설비를 검증하였다.