SYNTHESIS OF NANO-NICKEL-COATED MICRO-ALUMINUM AND THERMAL REACTIVITY OF ALUMINUM/NICKEL-STANNIC-OXIDE THERMITE

摘要

The displacement method was employed to modify the surface of micron Al on which a layer of Ni nanoparticles were coated. NH_4F acted as a key that enabled the displacement reaction to occurr. Al/Ni composites (with different coating percentage) were mixed with SnO_2 and the mixtures were used as thermites. The thermite reaction of Al/Ni-SnO_2 was investigated. For reactions between Al/Ni and SnO_2, the onset temperature was lowered and the reaction heat remarkably increased compared with the Al-SnO_2 reaction. Thermites Al-SnO_2 and Al/Ni-SnO_2 were heated simultaneity to 1020℃. The heated residues were investigated by scanning electron microscope, energy-dispersive spectroscopy, and x-ray diffraction analyses. Residue of raw Al manifested hollow shells composed of Al, α-Al_2O_3, and [θ]-Al_2O_3; residue of Al/Ni exhibited broken fragments and bulk sinters consisting of α-Al_2O_3, AlN, [θ]Al_2O_3, and faint NiO.