SMELTING OF NIOBIUM PENTOXIDE IN A TRANSFERRED ARC ARGON PLASMA AND CHARACTERIZATION OF THE SMELTED PRODUCT

Abstract

Smelting of Nb(2)O(5) was carried out in a dc extended arc argon plasma using carbon as the reductant. Plasma was produced in a reactor operating in transferred arc configuration (normal polarity mode). The plasma smelted product was analysed and found to contain up to 97.5% Nb with 86% (all by wt.) metal recovery. Characterization of the smelted product by XRD shows that majority of reflections are due to Nb metal and carbon occurs in the form of carbide. One minor reflection due to Nb(2)O(5) was recorded which is attributed to the unreacted oxide. Wavelength dispersive spectra of x-ray confirmed the carbon presence in the smelted product. Micro Raman spectroscopy study makes a comparison between the spectra due to smelted product and that of high pure superconductor grade Nb in order to identify presence of any carbide and/or oxide in the metal. Optical and scanning electron microscope studies reveal the typical surface morphologies of the plasma smelted Nb. Plasma smelted Nb has a good scope for use as a starting material towards preparation of high pure Nb for application in superconductors and electronic capacitors. This can be achieved by suitable removal of carbon followed by electron beam melting of the metal.