Bello Michael N, Williams Alan M, Levitas Valery I, Tamura Nobumichi, Unruh Daniel K, Warzywoda Juliusz, Pantoya Michelle L
Department of Mechanical Engineering, Texas Tech University Lubbock TX 79409 USA
Departments of Aerospace Engineering and Mechanical Engineering, Iowa State University and Ames Laboratory, Division of Materials Science and Engineering Ames IA 50011 USA.
RSC Adv. 2019 Dec 9;9(69):40607-40617. doi: 10.1039/c9ra04871e. eCollection 2019 Dec 3.
Energetic films were synthesized using stress altered nano-aluminum particles (nAl). The nAl powder was pre-stressed to examine how modified mechanical properties of the fuel particles influenced film reactivity. Pre-stressing conditions varied by quenching rate. Slow and rapid quenching rates induced elevated dilatational strain within the nAl particles that was measured using synchrotron X-ray diffraction (XRD). An analytical model for stress and strain in a nAl core-AlO shell particle that includes creep in the shell and delamination at the core-shell boundary, was developed and used for interpretation of strain measurements. Results show rapid quenching induced 81% delamination at the particle core-shell interface also observed with Transmission Electron Microscopy (TEM). Slower quenching elevated dilatational strain without delamination. All films were prepared at approximately a 75 : 25 Al : poly(vinylidene fluoride) PVDF weight ratio and were 1 mm thick. A drop weight impact test was performed to assess ignition sensitivity and combustion. Stress altered nAl exhibited greater energy release rates and more complete combustion than untreated nAl, but reaction dynamics and kinetics proceeded in two different ways depending on the nAl quenching rate during pre-stressing.
利用应力改变的纳米铝颗粒（nAl）合成了高能薄膜。对nAl粉末进行预应力处理，以研究燃料颗粒改性后的机械性能如何影响薄膜的反应活性。预应力条件因淬火速率而异。使用同步加速器X射线衍射（XRD）测量了慢速和快速淬火速率在nAl颗粒内引起的膨胀应变升高。建立了一个包含壳层蠕变和核壳边界分层的nAl核-AlO壳颗粒应力和应变分析模型，并用于解释应变测量结果。结果表明，快速淬火在颗粒核壳界面处引起了81%的分层，这也通过透射电子显微镜（TEM）观察到。较慢的淬火提高了膨胀应变而没有分层。所有薄膜均以约75∶25的Al∶聚偏氟乙烯（PVDF）重量比制备，厚度为1mm。进行了落锤冲击试验以评估点火敏感性和燃烧情况。与未处理的nAl相比，应力改变的nAl表现出更高的能量释放速率和更完全的燃烧，但反应动力学和动力学根据预应力过程中的nAl淬火速率以两种不同的方式进行。
