Thermal explosion in Al-Ni system: influence of mechanical activation.
Thermal explosion in Al-Ni system: influence of mechanical activation.
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DOI：
10.1021/jp905175c
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发表时间：
2009-10
期刊：
影响因子：
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通讯作者：
J. D. White;R. Reeves;S. Son;A. Mukasyan
中科院分区：
文献类型：
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作者：
J. D. White;R. Reeves;S. Son;A. Mukasyan
研究了短时高能球磨（5-15 min）对Ni-Al非均相反应体系点火特性的影响。通过使用Al-Ni包层颗粒（直径为30-40微米的Al球，表面涂有3-3.5微米的Ni层，相当于1：1的Ni/Al原子比），结果表明，这种机械处理导致系统自燃温度显着降低。例如，球磨15分钟后，点火温度似乎约为600 K，远低于所考虑的二元体系中的共晶（913 K），该共晶是初始包覆颗粒的点火温度。因此，它被证明，热爆炸过程的机械处理的反应介质可以单独定义的固态反应。此外，热分析测量结果表明，机械活化导致Al和Ni之间的相互作用的有效活化能（从84到28千卡/摩尔）的大幅下降。这种效应，即化学反应的机械活化，与反应性颗粒和在球磨期间在惰性气氛中形成的新鲜相间边界之间的接触面积的显著增加有关。同样重要的是，通过改变机械活化的时间，可以精确地控制高密度高能非均相系统的点火温度。
The influence of short-term (5-15 min) highly energetic ball milling on the ignition characteristics of a gasless heterogeneous Ni-Al reactive system has been investigated. By using Al-Ni clad particles (30-40 microm diameter Al spheres coated by a 3-3.5 microm layer of Ni, that corresponds to a 1:1 Ni/Al atomic ratio), it was shown that such mechanical treatment leads to a significant decrease in the self-ignition temperature of the system. For example, after 15 min of ball milling, the ignition temperature appears to be approximately 600 K, well below the eutectic (913 K) in the considered binary system, which is the ignition temperature for the initial clad particles. Thus, it was demonstrated that the thermal explosion process for mechanically treated reactive media can be solely defined by solid-state reactions. Additionally, thermal analysis measurements revealed that mechanical activation results in a substantial decrease in the effective activation energy (from 84 to 28 kcal/mol) of interaction between Al and Ni. This effect, that is, mechanical activation of chemical reaction, is connected to a substantial increase of contact area between reactive particles and fresh interphase boundaries formed in an inert atmosphere during ball milling. It is also important that by varying the time of mechanical activation one can precisely control the ignition temperature in high-density energetic heterogeneous systems.