Role of Voltage and Gas Pressure in Determining the Mean Diameter of Sn-Bi-Ag Intermetallic Compound Nanoparticles Formed by Pulsed Wire Discharge

Abstract

Nanoscale Sn-Bi-Ag compound powders were successfully synthesized using the pulsed wire discharge (PWD) method. In PWD, when a high current is passed through high-density metal wires, the wires explode because of resistance heating, forming fine particles or metal vapor. In this study, we used Sn-Bi and Ag wires in order to obtain three-component nanopowders. A high current was applied to the wires between the electrodes in a N2 atmosphere. We discussed the results based on the K factor, which is the ratio of the charging energy of the capacitor to the vaporization energy of the wire. The three-component (Sn-Bi-Ag) nanoparticles were synthesized under a N2 atmosphere at 4 and 6 kV. From the particle-size distribution curves, it was found that the mean particle diameter (D1) values of the Sn-Bi and Ag nanopowders were within the range of 16.32-42.37 nm under each condition. The melting point of the Sn-Bi-Ag nanoparticles was found to be within the range of 188.68-214.97 ℃, which is about 40 ℃ lower than that obtained from the phase diagram and computational thermodynamics of the Sn-Bi-Ag system. In this study, the nanopowders were obtained by subjecting the wires at extreme energies, to improve their solid solubility. (Received February 8, 2017; Accepted July 26, 2017)