Ni包覆纳米Al粉在CO2气氛中热反应特性及动力学研究

Thermal Reaction Characteristics and Kinetics of Nano-Aluminum Powder Coated with Nickel in Carbon Dioxide

关键词:  纳米铝粉  二氧化碳  包覆  热反应特性  动力学

Key words:  Nano-Aluminum  Carbon dioxide  Coated  Thermal reaction characteristics  Kinetics

摘要:

为解决点火困难、燃烧效率低的问题，采用热分析仪研究了镍包覆纳米铝粉在二氧化碳气氛下的热反应特性和反应动力学。结果表明:对纳米铝粉表面进行镍包覆可有效降低纳米铝粉的着火温度，缩短其反应时间。升温速率在5℃/min，10℃/min和15℃/min时，镍包覆纳米铝粉与未包覆纳米铝粉相比，其着火温度分别下降了64.0℃，71.0℃和76.0℃；反应时间缩短了9.8min，6.6min和4.0min。采用Coats-Redfern法结合Malek法，选择合理的动力学模型并计算得到相应的反应动力学参数。结果表明，镍包覆纳米铝粉和未包覆纳米铝粉的氧化反应机理存在明显的差别；镍包覆纳米铝粉降低了其与二氧化碳反应的活化能，同时，研究发现，升温速率并不能改变未包覆纳米铝粉和镍包覆纳米铝粉在二氧化碳气氛中的反应机理。

Abstract:

Al/CO₂ reaction can be used as an ideal fuel for the future manned Mars exploration. At present，however，the reaction of Al/CO₂ has encountered "bottleneck" problems which are the high ignition temperature and low combustion efficiency. In order to lower the ignition temperature and improve the combustion efficiency，the surface of aluminum powder must be reasonably modified. Thermal reaction characteristics and kinetics of nano-aluminum powder coated with nickel were studied in carbon dioxide by the thermal analysis techniques. The results show that ignition temperature and reaction time of nano-aluminum powder are decreased by nickel coating nano-aluminum powder. Compared with nano-aluminum，ignition temperature of nickel coating nano-aluminum powder is decreased by 64.0 ℃，71.0 ℃，76.0 ℃ and reaction time is decreased by 9.8min，6.6min，4.0min at the heating rate of 5℃/min，10℃/min and 15℃/min，respectively. Using Coats-Redfern method combined with Malek method，reasonable models are chosen and kinetic parameters are calculated. The results show that the mechanisms of nano-aluminum powder and nano-aluminum powder coated with nickel are different in carbon dioxide. The activation energy of nano-aluminum powder coated with nickel is lower than that of nano-aluminum powder. Moreover，it is found that the reaction mechanisms of nano-aluminum powder and nano-aluminum powder coated with nickel have not changed with the increasing heating rate.