How Fine Grain Tungsten Produced?
- 詳細
- カテゴリ: Tungsten Information
- 2015年2月11日（水曜）17:05に公開
- 参照数: 1541
At present, micrometer tungsten powder was used for the production and research of tungsten materials. This type of tungsten powder is sintered at a temperature higher than 2000℃ in order to be densified. Thereafter, it can be further processed. However, tungsten grain size increases quickly during the sintering, and may be up to several hundreds micrometers. These coarse tungsten grains lower the mechanical and physical properties as well as rolling characteristic. Nanoscale powder has more surface energy and can be densified more easily than micrometer powder. Nanoscale WO3 powder was prepared from the APT (ammonium paratungstate) solution by the ultrasonic spray thermo-conversion process, and was then reduced in hydrogen. The reduction was canned out in two steps. WO3 was first reduced to the blue tungsten oxide WO2.90, and then WO2.90 was reduced to tungsten. In the above process, nanoscale WO3, WO2.90 and tungsten powders were milled by the high energy shear miller. The specific surface area of these nanoscale powders was measured by an ST-03 specific surface area tester, by which an average particle size was calculated. The powder shape was observed with an H-800 TEM (transmission electron microscopy). Nanoscale tungsten powder was formed with a rubber die and a steel die respectively. The compact density was measured based on the Archimedes method. Nanoscale tungsten compact was sintered in hydrogen at a temperature elevating rate of 10℃/min with a high temperature dilatometer. Furthermore, conventional tungsten powder with an average particle size of 2.5 um was compacted and sintered to compare with the nanoscale tungsten powder.
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