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Thermo-physical Characteristics of Nickel-coated Aluminum Powder as a Function of Particle Size and Oxidant

Chinese Journal of Mechanical Engineering 2016年第6期29卷 1244-1255页

作者： LEE Sanghyup NOH Kwanyoung lim jihwan YOON Woongsup Advanced Energy and Propulsion Laboratory Department of Mechanical Engineering Yonsei University Missile System Integration / propulsion Center Hanwha Corp.

Aluminum particles 15-25 μm in size are widely used in fuel propellants and underwater propulsion systems in national defense research. However, these particles are covered with an aluminum oxide film, which has a high melting point, so ignition is difficult. To improve the ignitability of high-energy aluminum powder and to understand the reaction phenomenon as a function of particle size（15-25 μm, 74-105 μm, and 2.38 mm） and oxidizer（air, CO2, and argon）, the natural oxide films are chemically removed. The particles are then coated with nickel using an electro-less method. The degree of nickel deposition is confirmed qualitatively and quantitatively through surface analysis using scanning electron microscopy/energy dispersive spectroscopy. To characterize the nickel coatings, elemental analysis is also conducted by using X-ray diffraction. Thermogravimetric analysis/differential scanning calorimetry （TGA/DSC） enable comparisons between the uncoated and coated aluminum, and the reaction process are investigated through fine structural analysis of the particle surfaces and cross sections. There are little difference in reactivity as a function of oxidant type. However, a strong exothermic reaction in the smaller nickel-coated aluminum particles near the melting point of aluminum accelerates the reaction of the smaller particles. Explanation of the reactivity of the nickel-coated aluminum depending on the particle sizes is attempted.

关键词： nickel-coated aluminum TGA/DSC aluminum ignition combustion intermetallic reaction

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A Steam-Plasma Igniter for Aluminum Powder Combustion

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Plasma Science and Technology 2015年第5期17卷 392-401页

作者： Sanghyup LEE Kwanyoung NOH jihwan lim Woongsup YOON Mechanical Engineering Department of Yonsei University

High-temperature ignition is essential for the ignition and combustion of energetic metal fuels, including aluminum and magnesium particles which are protected by their high- melting-temperature oxides. A plasma torch characterized by an ultrahigh-temperature plasma plume fulfills such high-temperature ignition conditions. A new steam plasma igniter is designed and successfully validated by aluminum power ignition and combustion tests. The steam plasma rapidly stabilizes in both plasma and steam jet modes. Parametric investigation of the steam plasma jet is conducted in terms of arc strength. A high-speed camera and an oscilloscope method visualize the discharge characteristics, and optical emission spectroscopy measures the thermochemical properties of the plasma jet. The diatomic molecule OH fitting method, the Boltzmann plot method, and short exposure capturing with an intensified charge coupled device record the axial distributions of the rotational gas temperature, excitation temperature, and OH radical distribution, respectively. The excitation temperature at the nozzle tip is near 5500 K, and the gas temperature is 5400 K.

关键词： steam plasma igniter aluminum emission spectroscopy energetic metal fuels powder ignition and combustion optical

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Complete recovery from segmental zoster paresis confirmed by magnetic resonance imaging:A case report

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World Journal of Clinical Cases 2022年第26期10卷 9434-9439页

作者： jihwan Park Wooyong Lee Yunhee lim Department of Anesthesiology and Pain Medicine Sanggye Paik HospitalInje University College of MedicineSeoul 01757South Korea

BACKGROUND Segmental zoster paresis,depending on the affected area,can present with severe clinical manifestations and render patients unable to perform activities of daily ***,it is necessary to diagnose and treat such a condition *** studies have reported using magnetic resonance imaging(MRI)to identify clinical abnormalities associated with this condition or its complete *** rare case report evaluated the changes in MRI findings before and after the patient’s motor symptoms *** SUMMARY A 79-year-old woman with a history of rheumatoid arthritis and psoriasis visited the hospital for skin rashes and pain in the C5-T2 *** diagnosis was herpes zoster infection,and treatment was ***,motor weakness suddenly occurred 14 d after the initial symptom *** confirmed abnormal findings in the nerves and muscles invaded by the shingles using electromyography and *** 17 mo,the patient’s symptoms had completely normalized,and MRI confirmed that there were no *** MRI can be a useful diagnostic modality for segmental zoster paresis and patient evaluation during recovery from motor complications.

关键词： Complication Electromyography Herpes zoster Magnetic resonance imaging Paresis Case report

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