Nano violet tungsten oxide powder can not only be applied for producing thermal insulation masterbatch and therefore be applied to manufacture thermal insulation film, but also be used as a raw material for the preparation of submicron tungsten powder.
Preparation of Submicron Tungsten Powder by Cyclic Reduction-oxidation of Violet Tungsten Oxide
1. Raw materials. The violet tungsten has specific surface area (BET) of 0.128m2?g-1. The purity of hydrogen gas is 99.9%, the dew point is less than -40°C, and the alcohol is analytical pure.
2. Equipment. High-temperature single-tube reduction furnace, furnace size is Y22mm×180mm, rated power is 2.5kW, rated voltage is 30～220V, and rated temperature is 1300°C. Laser particle size analyzer; Electronic probe scanner.
3. Experimental procedures.
(1) The first reduction of violet tungsten oxide is conducted in hydrogen, the temperature of the belt is 640°C, the temperature of the two belts is 760°C, the temperature of the three belts is 860°C, and the temperature is maintained at 860°C for 20min;
(2) The tungsten powder of (1) is slowly heated to 500°C in the air for the first oxidation, and the temperature is maintained at 500°C for 10 min;
(3) Using the test sample of (2) and the process conditions of (1) and (2), performing a reduction oxidation test in a continuous cycle;
(4) Using the analytical pure alcohol, the test results of the above steps were dispersed, and then the particle size and morphology were analyzed by laser particle size analyzer and electron probe scanner.
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