Thermal stability and spatial distribution of sodium chloride alone and in the presence of several metal salts on a graphite platform

Abstract

A systematic thermal treatment of a matrix constituted by sodium chloride alone and together with protons, Ni, Pd and Th, was investigated for use with platform atomisation. The distribution of solid precursors on the platform surface was derived at different temperatures. Localisation of solid residues on the graphite surface was possible by using a scanning electron microscope and determination of their composition was carried out by energy dispersive X-ray microanalysis. The distribution of NaCl appeared as relatively large particles on the platform surface, contrarily to other metal chlorides and nitrates, which show a fine granulometry. It was also stated that sodium chloride is retained on the graphite surface up to high temperatures (about 950 °C), being then vaporised. However, sodium chloride molecules are vaporised or destroyed at much lower temperatures if protons (from nitric acid) are present, regardless of the presence of Ni and Th. Nevertheless, the presence of Pd hinders thermal vaporisation conditions for sodium chloride, even together with protons.