• Journal of Korea Foundry Society
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• v.31 no.2
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• pp.60-65
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• 2011

Molten magnesium alloys and magnesium products are easily oxidized and burned when they are exposed to high temperature for manufacturing process and by accident. In order to solve these problems, CaO addition in magnesium alloys has been developed. The ignition resistance of CaO added Mg-3Al, Mg-6Al, and Mg-9Al Eco-Mg alloys were investigated in comparison with those of magnesium alloys without CaO. The ignition resistance was examined by three methods : DTA, furnace chip ignition test, and torch ignition test. DTA was carried out for obtaining quantitative ignition temperature data with respect to specimen geometry and test environment; the furnace ignition test for burr and chip ignition temperature data; and the torch test for ignition temperature data for manufactured products. The ignition resistance of magnesium alloys under all conditions greatly increased by CaO addition.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.235-241
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• 1996

Self-Propagating high temperature synthesis(SHS) technique was used to synthesize the spinel phase of MgAl2O from MgO and Al powder. Processing factors such as mixing time preheating temperature and ignition catalyst were varied to determine the optimum condition to form MgAl2O4 phase. The reaction products were heat treated at the temperature range of 120$0^{\circ}C$ and 150$0^{\circ}C$. to observe phase transformation of unreacted materials. Processing factors such as 48 hrs-mixing 80$0^{\circ}C$-preheating and 20wt% KNO3-ignition catalyst were effective of the formation of MgAl2O spinel. An activation energy 49.7kcal/mol. was calculated to form a MaAl2O4 spinel from unreacted materials.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.79-88
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• 2017

Ignition test of the fuel-rich propellant coated with ignition support material in the ramjet combustor condition was conducted. Ignition delay and flame holding was measured. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Al particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. Ethanol blended $H_2O_2$ gas generator control the temperature, pressure, $O_2$ concentration in the oxidizer gas in the air. Gas is supplied with mass flux of $200kg/m^2s$. Through the test ignition support operated well and ignition delay of 0.6 second and the Flame was sustained.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.5-8
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• 2013

The ignition of aluminum particles under high pressure and temperature conditions is studied. The laser ablation method is used to generate aluminum particles exposed to pressures ranging between 0.35 and 2.2 GPa. A continuous wave $CO_2$ laser is then used to heat surface of the aluminum target until ignition is achieved. We confirm ignition by a spectroscopic analysis of AlO vibronic band of 484 nm wavelength. The radiant temperature is measured with respect to various pressures for tracing of required heating energy for ignition. Then the ignition temperature is deduced from the radiant temperature using the thermal diffusion equation. The established ignition criteria for corresponding temperature and pressure can be used in the modeling of detonation behavior of heavily aluminized high explosives or solid propellants.

• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.303-307
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• 2001

The ignition of propane was investigated behind reflected shock waves in the temperature range of 1350-1800 K and the pressure range of 0.75-1.57 bar. The ignition delay time was measured from the increase of pressure and OH emission in the C3H8-O2-Ar system. The relationship between the ignition delay time and the concentrations of propane and oxygen was determined in the form of mass-action expression with an Arrhenius temperature dependence. The numerical calculations were also performed to elucidate the important steps in the reaction scheme of propane ignition using various reaction mechanisms. The ignition delay times calculated from the mechanism of Sung et al.1 were in good agreement with the observed ones.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.101-103
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• 2012

Characteristic of aluminum ignition under high temperature and high pressure is studied using lasers. The laser ablation method is used to generate aluminum particles exposed to a high pressure by using a nanosecond pulsed laser where the range of ablation pressure varies between 0.35 and 2.2 GPa. A $CO_2$ laser is used to supply radiative heat to the aluminum target surface for providing high temperature ranging between 5000~9300 Kelvin. The ignition is confirmed using spectroscopy analysis of AlO vibronic band 484 nm wavelength. Also the radiative temperature is measured in various high pressure range for tracing the ignition temperature in high pressure conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.202-205
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• 2010

Auto ignition of hybrid rocket using $N_2O$ catalytic decomposition was studied in the present study. The hybrid rocket consists of catalytic igniter, solid fuel, combustor, and nozzle. The Ru/$Al_2O_3$ catalyst for $N_2O$ decomposition was synthesized by an impregnation method, and $N_2O$ conversion as reaction temperatures was measured. The temperature change of the catalytic ignitor was measured at the operating condition, and the possibility for the auto ignition of hybrid rocket was validated.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.77-77
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• 2013

최근의 산업활동에서는 신규 원료 개발과 생산 효율성을 높이기 위하여 분체 공정이 증가하고 있는데, 미세 분진의 취급으로 분진운의 형성과 착화가 용이해지므로 분진폭발이나 화재 위험성이 증가하고 있다. 분진을 안전하게 사용하고 저장, 취급하기 위해서는 착화 전의 위험성 지표로서 최저발화온도(MIT ; Minimum Ignition Temperature)를 사전에 파악해 두는 것이 중요하다. 분진농도의 발화온도는 장치 내의 발화위험성이나 분진 취급 공정의 사고예방대책 관리를 위한 실용적 관점에서 중요하게 활용되는 폭발특성값이다. 또한 분진의 발화온도는 분진농도에 의존하며 농도변화에 따른 가장 낮은 온도를 MIT라고 한다. 본 연구에서는 화재폭발사고 빈도가 줄지 않고 있는 Mg 및 Mg-Al합금(60:40 wt%, 50:50 wt%, 40:60 wt%)을 대상으로 조성비율에 따른 최저발화온도를 실험적으로 조사하였다. Mg 및 Mg-Al(60:40 wt%), Mg-Al(50:50 wt%), Mg-Al(40:60 wt%) 시료의 평균입경은 142, 160, 151, $152{\mu}m$이다. MIT실험장치는 IEC 61241-2-1(Methods for Determining the Minimum Ignition Temperatures of Dust, 1994)에 준거하여 제작하여 사용하였다. 실험장치는 가열로, 분진운 시료홀더, 온도조절장치, 압축공기 제어장치 등으로 구성되어 있다. 구체적인 실험방법은 시험분진를 분진홀더에 장착하고 0.5 bar의 압축공기를 0.3 sec 동안 사용하여 일정 온도로 가열된 로의 내부로 분진운을 부유시킬 때에 분진운이 발화하여 가열로 하단부의 개방구에까지 화염이 전파하는지를 디지털비데오카메라로 기록, 평가하여 발화 유무를 판정하였다. Mg합금에 대한 MIT를 측정한 결과 $740^{\circ}C$가 얻어졌으며, Mg-Al(60:40 wt%)의 MIT는 $820^{\circ}C$로 조사되었다. 그러나 Mg-Al(50:50 wt%) 및 Mg-Al(40:60 wt%)에 대해서는 최대 가열로의 설정온도를 $890^{\circ}C$까지로 하여 농도를 변화시키면서 조사하였으나 발화가 일어나지 않았다. 문헌에 따르면 Mg입자 표면의 산화피막은 다공성으로 일정 온도에서 산화반응이 시간에 따라 직선적으로 증가하는데 반하여, Al의 산화피막은 보호 작용을 하여 일정 온도에서 산화반응속도가 표면과 내부의 농도 기울기에 의한 확산속도에 의존한다고 보고하고 있다. 본 연구결과를 토대로 Mg-Al합금의 발화특성을 고찰해 보면, Mg-Al합금에서 자기 전파성이 작은 Al성분의 증가는 착화지연이 증가하여 연소성이 감소하여 최저발화온도의 증가로 이어지는 것으로 추정되었다. 또한 발화온도는 주어진 조건의 온도장에서 분진이 존재하는 시간 길이에 따라 변화하므로, 발화온도를 실험적으로 측정하는 경우에는 측정장치나 방법에 따라 달라지므로 사업장의 현장에 발화온도를 적용하는 경우에는 장치 내의 분진의 존재시간을 고려할 필요가 있다.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.39-45
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• 2013

Basically, in order to apply solid propellant as ignition source to high energy metal particle combustion system, we analyzed combustion characteristics of the HTPB/AP/Al, HTPE/AP/Al propellants by using a strand burner. The propellants were tested in a high-pressure windowed strand burner, which was pressurized up to 300 psia with pure argon gas. Strand burner was visualized with two quartz windows and ignition was accomplished by a 10 W $CO_2$ laser. The burning rate of propellant was measured with high-speed camera method for frame analysis and photodiode method for combustion time analysis. Emission spectrum was measured with spectrometer at 300 nm ~ 800 nm and 1500 nm ~ 5000 nm and then we analyzed species during propellant combustion.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.351-355
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• 2011

In this study, 2 kinds of HTPE insensitive propellants composed of HTPE/BuNENA binder, AP, AN and Al were investigated for combustion characteristics, ignition delay time, sensitivity and insensitive properties compared with HTPB propellant. HTPE propellant showed almost same sensitivity results as HTPB propellant, showed 2~3 times higher value than the value of HTPB propellant, ignition delay time respectively, and met the standard criteria, while HTPB propellant failed.