shows the variation of both mean-diameter and mass-mean-diameter of both
anodic and cathodic particles with gas pressure. Mass-mean-diameter is defined as
MMD = (Σmidi ) /Σmi where i m and i d are mass and diameter of ith particle, and the
summation is over all particles [ 28]. Anode particles were always significantly larger than
cathodic particles. Particle size increased as gas pressure was reduced. Drag forces exerted by the
gas are the main reason for atomization of molten material from the wire tips. Droplets of molten
metal are formed when the drag and magnetic forces that tear liquid off the wire tip exceed
surface tension forces attaching it to the wire. As gas pressure decreases so does its velocity and
therefore drag forces. Molten metal droplets grow larger before detaching from the wire tip when
drag forces diminish. Moreover, secondary atomization that breaks the molten material into
smaller droplets tends to produce smaller particles with increasing gas flow velocity