Synthesis and exothermic reactions of ultra-fine snowman-shaped particles with directly bonded Ni/Al interfaces

摘要

Nickel-nanoparticle-attached aluminum (Ni/Al) particles are synthesized by plating Ni onto Al particles with the surface oxide partly removed. The microstructure of the synthesized Ni/Al particles resembles a child's snowman, with an approximately 200 nm spherical Ni nanoparticle bonded onto the surface of an Al particle about 800 nm in size. Particularly, the surface oxide is rarely observed at the Ni/Al interfaces unlike uncoated surface of the Al powder. Due to these microstructural characteristics, it was clearly noted that a self-propagating high-temperature synthesis (SHS) reaction of the snowman-shaped Ni/Al (SNA) particles occurs more actively compared to that which occurs when simply mixing particles of Ni and Al in the temperature range of 720-900 K. The formation of intermetallic compounds of NiAl or NiAl3 is confirmed in a comparison of XPS results after both samples were oxidized at 773 K. The exothermic enthalpy energy, 8,850 Jg(-1) of SNA particles represents 118% of the value of 7,580 Jg(-1) for the mixed particles. These results indicate that SNA particles are promising as advanced reactive materials when used in conjunction with an efficient SHS reaction.