Kim Dong Won, Kim Kyung Tae, Kwon Gu Hyun, Song Kyung, Son Injoon
Korea Institute of Materials Science, 797 Changwondaero, Seongsan-gu, Changwon, Gyeongnam, 51508, Republic of Korea.
Kyungpook National University, 80 Daehakro, Buk-gu, Daegu, 41566, Republic of Korea.
Sci Rep. 2019 Jan 31;9(1):1033. doi: 10.1038/s41598-018-36760-y.
Aluminum powders are known to provide outstanding volumetric exothermic enthalpy energy during thermal oxidation. However, the amount of energy released tends to be limited by the dense surface oxide (AlO) layer of the powder. Hence, a prerequisite for improving the reactivity of passivated Al particles is to remove the AlO film from the surface. Considering that the self-propagating high-temperature synthesis (SHS) reaction of Ni and Al can generate additional exothermic heat in Al powder, Ni can be considered as a promising alternative to the surface oxide layer. Here, we report oxide-layer-free fine Al particles with a characteristic Ni/Al interface, where a Ni layer replaces the AlO film. The microstructure of the synthesized powder consists of a 200-nm-thick Ni layer homogeneously coated on the Al surface, which has nanosized craters caused by the geometrical removal of AlO. Thermal analysis and in-situ heating transmission electron microscopy (TEM) results clearly show that active interdiffusion of atoms through the Ni/Al interface results in the formation of intermetallic compounds to provide additional exothermic energy, compared to the result for simply mixing Ni and Al powders. Hence, these findings provide new routes for the design and application of reactive metallic particles using the SHS reaction.
众所周知，铝粉在热氧化过程中能提供出色的体积放热焓能。然而，释放的能量往往受到粉末致密表面氧化物（AlO）层的限制。因此，提高钝化铝颗粒反应活性的一个先决条件是去除表面的AlO膜。考虑到Ni和Al的自蔓延高温合成（SHS）反应会在铝粉中产生额外的放热，Ni可被视为表面氧化物层的一种有前景的替代物。在此，我们报道了具有特征性Ni/Al界面的无氧化层细铝颗粒，其中Ni层取代了AlO膜。合成粉末的微观结构由均匀包覆在Al表面的200纳米厚Ni层组成，Al表面因AlO的几何去除而有纳米级坑洼。热分析和原位加热透射电子显微镜（TEM）结果清楚地表明，与简单混合Ni和Al粉末的结果相比，原子通过Ni/Al界面的活性互扩散导致金属间化合物的形成，从而提供额外的放热能。因此，这些发现为利用SHS反应设计和应用活性金属颗粒提供了新途径。
