2020年12月21日星期一

Submicron Tungsten Powder Preparation by APT Cyclic Oxidation Reduction Method

Tungsten powder is mainly used to manufacture tungsten filament for incandescent lamp, inert gas shielded arc welding and atomic hydrogen welding electrode etc..

Submicron tungsten powder has the advantages of fine particle, well-developed surface, high activity, it is not as stringent as the preparation of nano tungsten powder, and the application range is better than ordinary tungsten powder, so the application scope is more and more widely. 

There are many main methods for preparing submicron tungsten powder at home and abroad: they are high-energy ball milling, dry atmosphere reduction, violet tungsten hydrogen reduction, molten salt electrolysis and plasma technology, etc. There are still many shortcomings in the preparation of submicron tungsten powder, such as time consuming, energy consumption, low production efficiency, high production cost, and difficult to realize industrial production. So the next to introduce an innovative submicron tungsten powder preparation method - ammonium paratungstate cycle oxidation reduction method.



The cyclic oxidation reduction method of ammonium tungstate was put forward by scholar Fu Xiaoming. Its main feature is the ammonium tungstate calcined in the air as tungsten trioxide, and then the use of cyclic oxidation reduction preparation of sub-micron tungsten powder, this feature is less pollution, simple and easy process route, easy to control process parameters, simple equipment and suitable for mass production of industrialization and so on, the submicron tungsten powder particle size distribution range is narrow, the structure is spherical, which is conducive to the homogenization of tungsten powder compacts in sintering process, and can achieve good size control.

Ammonium paratungstate oxidation reduction method is carried out under the reduction furnace, the main feature is the cycle of recycling, roughly as follows: the special pure ammonium paratungstate in argon to slow the temperature rise to 800 °C, holding 10 min, the tungsten powder was prepared by the first reduction of the tungsten powder and tungsten powder in the air to 500 °C for the first time. When the temperature reached 500 °C, the temperature was kept for 10 min, tungsten trioxide → tungsten oxide is prepared in hydrogen for the second time. Tungsten powder is also prepared. The second oxidation is carried out using the obtained tungsten powder. The second oxidation is carried out to obtain tungsten trioxide. To obtain tungsten trioxide → the third reduction was carried out again with the obtained tungsten trioxide to prepare submicron tungsten powder.

The process and equipment used to prepare submicron tungsten powder by cyclic oxidation of ammonium paratungstate are similar to those of traditional industrial production of tungsten powder. Therefore, the process route is simple and easy, the process parameters are easy to control, the equipment is simple, suitable for industrial production in large quantities.

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