Preparation of hexagonal boron nitride nanoparticles by non-transferred arc plasma

Hexagonal boron nitride (h-BN) nanoparticles were prepared from micro-sized h-BN powder by using a non-transferred arc plasma system at atmospheric pressure. Two kinds of the thermal plasma forming gas, Ar and Ar–N₂ mixture, were employed to control temperature and thermal conductivity of thermal plasma jet. The flow rate of the nitrogen which was used as additive plasma forming gas with argon ranged from 1 to 3 L/min at the total thermal plasma forming gas flow rate of 15 L/min. Input power with arc current and arc voltage was changed by composition of plasma forming gas. Kind of the plasma forming gas as Ar and Ar–N₂ mixed gases and the input power were main parameters in this work. As a result, only h-BN nanoparticles without other impurities were produced at the operating condition that flow rate of N₂ was 3 L/min with 13.7 kW. High thermal conductive N₂ gas help to promote the heat transfer for the vaporization of precursor due to enhanced input power and joule heating effect by increased arc voltage. In other plasma discharge conditions, h-BN precursor could not be completely evaporated or boron oxide as impurity was produced as the product.