Features of micro and nano-particles produced by pulsed arc submerged in ethanol

Ni-C powders were synthesized using a pulsed arc between Ni electrodes submerged in pure ethanol. The arc pulses with energies 7.7, 22.7 or 48 mJ and 20 mu s duration, and a repetition rate of 100 Hz were applied for 5 min. Powder samples were obtained by extracting liquid from the treatment vessel after a pre-determined sedimentation time, or by collecting the residue after the liquid evaporated. The particles size distribution was studied using a High Resolution Transmission Electron Microscope (HRTEM). The particle diameters after 25 min sedimentation time were in the range of 3-30 nm, and the distribution depended weakly on the discharge energy. Effects of applied electric and magnetic fields on the particle motion in ethanol were also studied. The particles moved in an applied electric field with velocities increasing with the field strength and the particle diameter. The as-produced particles with diameter similar to 80 mu m had velocities similar to 2-2.5 mm/s in an electric field of similar to 800 V/cm. The powder had soft ferromagnetic properties at room temperature, and the particles in the liquid moved in the direction of increasing magnetic field. (c) 2005 Elsevier B.V. All rights reserved.