Influence of Ag Electrodes Asymmetry Arrangement on Their Erosion Wear and Nanoparticle Synthesis in Spark Discharge

Abstract

For nanoparticle synthesis in a spark discharge, the influence of the degree of electrode asymmetry in the rod-to-rod configuration, using the example of silver electrodes, on the energy efficiency and nanoparticle composition is studied. The asymmetry degree was determined by the angle between electrodes’ end faces. Two types of discharge current pulses were used: oscillation-damped and unipolar, in which electrodes changed their polarities and had a constant polarity during a single discharge, respectively. A significant influence of the asymmetry degree of the electrode arrangement on the synthesized nanoparticle size, agglomeration and concentration, and on the synthesis energy efficiency, has been established. An increase in the degree of the electrode asymmetry with the oscillation-damped discharge current pulse led to an increased mass production rate and energy efficiency of nanoparticle synthesis, a significant fraction of which had large dimensions of more than 40 nm. The effect of the transfer of synthesized nanoparticles to the opposite electrode at the unipolar discharge current pulse led to the appearance of electroerosive instability, manifested in the formation of a protrusion on the anode surface, around which spark discharges, leading to its further growth and electrode gap closure.