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铁虫 (正式写手)

应助: 1 (幼儿园)
金币: 94.1
红花: 8
帖子: 306
在线: 68.5小时
虫号: 4532612
注册: 2016-03-23
专业: 高分子合成化学

[交流] 采用金属机械化对亚稳态的金属活性进行表征已有1人参与

Metal powders such as aluminum are commonly used as fuel additives to propellants, explosives, and pyrotechnics because of the improved performance they offer due to their high combustion enthalpies. However, heterogeneous oxidation of metals may cause long ignition delays, high ignition temperatures, low burn rates, and premature extinction leading to an incomplete combustion. Metalbased, mechanically alloyed materials have been proposed to improve ignition and combustion rates as a result of the metastable phase transitions that occur at low temperatures before, and sometimes during combustion. It is of interest to characterize these materials, and specifically, to explore how they behave under inert and oxidative environments upon heating. In this project, high-energy density, Al-based materials (i.e., Al·Mg, Al∙Ti, etc.) are prepared by mechanical milling. Differential scanning calorimetry (DSC) is used to identify and characterize reactions that occur upon their heating in different environments, including subsolidus phase changes, eutectic and pure metal melting, and formation of various oxidized products. Thermogravimetric analysis (TGA) measurements are used to help identify and quantify decomposition and oxidative behaviors. Exothermic reactions observed in DSC are correlated to oxidative weight gains observed in TGA. Kinetic correlations are found using isoconversion processing to identify the reactions that cause or contribute to ignition of the materials. Results of such correlations will be presented in the paper.

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