| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.23 ( October 1990 ) R&D of High-Technology Research Laboratories, Commemorating the 20th Anniversary of the Technical Research Division ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Preparation of Ultrafine Metallic Particles by Hydrogen Reduction of Chloride Vapors Hiroyuki Ishikawa, Ken-ichi Otsuka, Minoru Nitta, Yasunori Yonehara |
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Synopsis : Ultrafine particles of silver, copper and tungsten were prepared by the hydrogen reduction of chloride vapors, and the effects of reaction conditions on the shape, average size and size distribution of resultant particles were examined. Particle shape was spherical for silver and copper, and polyhedral for tungsten. Narrow log-normal distributions of particle size with geometric standard deviations between 1.2 and 1.4 were obtained regardless of the metals and their reaction conditions. Average particle diameters ranged from 20 to 1000 nm depending on the metals and their reaction conditions, and were controllable by selected chloride vapor concentration and reaction temperatures. Reaction conditions being equal, the particle size of silver was the largest, and that of tungsten was the smallest among the three. The ratio of the reaction temperature to the melting points is supposed to be an important factor in determining the size of ultrafine particles. |
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