关键词: 纳米粉, 形貌, 直流电弧, 蝌蚪型, 粉末粒度

Abstract: Producing nanopowders of Al, Fe, Cu and Pb by hydrogen plasma D. C. arc process and determining their morphologies, compositions, crystalline structures and particle sizes were studied. The results showed that they were all of monocrystals, among which the particle sizes of Al nanopowder distributed in a range from 10 to 138 nm with 75 nm on average, and the average size of Fe, Cu and Pb nanopowders were 56 nm, 81 nm and 77 nm, respectively. All of them are of fcc structure except α-Fe that is of bcc. When the volume of oxygen feed is the same, the feeding speed affects greatly the oxygen content of nanopowders. For example, the mass fraction of oxygen in Al nanopowder is about 5.9% after a passivation for 6 h and about 11.3% for 2 h. However, the result of X-ray diffraction analysis of Al nanopowder is different from that of others, because the oxygen is dissolved into Al nanopowder to split the diffraction peak. Thus, the lattice constant of part of powder particles increase by 0.0036 nm, though their structures remain unchanged. Unlike the spherical shape of particles of other nanopowders, the tadpole-like morphology features the particles of Al nanopowder.