On the Specific Surface Area of Tungsten Powder. (Study on the Surface States of Tungsten Powder (2))

Abstract

By the simplified gas adsorption procedure previously reported by the author, an investigation was made of the surface states of tungsten powder prepared by hydrogen reduction. It was found that, while the surfaces of particles of pure tungsten powder were smooth, those of doped tungsten were roughened and covered with a layer of the alkaline components of dopes. The surface area of doped powder was remarkably affected by pure water washing as well as by pickling in dilute alkaline or acidic solutions. The surface area was also changed by oxidation or reduction of the powder. In atmospheric air at room temperature, tungsten powder is oxidized. In such oxidation process, the surface area considerably changed in relation with the transition of oxidation rate. An explanation of these phenomena was proposed with the help of electron-microscopic observations.