中國(guó)有色金屬學(xué)報(bào)(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 16 No. 1 February 2006 |
and molybdenum powders
（1. Institute of Surface and Coatings Technology, School of Materials Science and Engineering,
Central South University, Changsha 410083, China;
2. Plasma Technology Research Center, University of Sherbrooke, Sherbrooke J1K 2R1, Canada）
Abstract:The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and the cross section of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed on the particle surface of these two metals. The influence of spray chamber pressure on the spheroidization and oxidation phenomena was discussed. The results show that fewer Mo particles than W particles are spheroidized at the same powder feed rate under the same plasma spray condition although molybdenum has a lower melting point. A small fraction of tungsten is evaporized and condensed either on the surface of tungsten particles nearby or on the wall of spray chamber. Tungsten oxides were found in tungsten powder processed under soft vacuum condition. Extremely large grains form inside some spheroidized particles of tungsten powder.
Key words: tungsten; molybdenum; induction plasma; melting; spheroidization; evaporation; oxidation
