Ultrafine Tungsten Powder Preparation by Raw Liquid Chemical Method

Tungsten has been widely used because of its high melting point (3410 ℃) and excellent physical and chemical properties, such as rocket and aircraft engine parts, gas rudder control components, rocket's forebody, contact plug, radiator and so on.

However, if the application requirements in these fields are to be fully met, it is difficult to sinter densified tungsten powder with micron size by traditional powder metallurgy method, which usually requires a high sintering temperature and a long sintering time, and the yield is low. Activated sintering developed in recent years is an effective way to improve density. The difficulty of activated sintering is how to obtain tungsten alloy with high density at low temperature. The key is to use ultrafine tungsten powder.

In view of this, some scholars have applied ultrasonic treatment and surfactant to prepare ultrafine tungsten powder on the basis of the original liquid phase chemical method. How is it different from the traditional method? Take a look at the steps of its research and implementation:

(1)The surfactant was dissolved in deionized water or distilled water, dispersed and dissolved by mechanical stirring and ultrasonic treatment, and then ammonium paratungstate (APT) was added into the prepared solution.

(2)The concentration of 65%-68% HNO₃ was added to the above solution under mechanical stirring and ultrasonic conditions for chemical precipitation reaction to form suspension.

(3)Adding anhydrous ethanol to the suspension to continue the reaction, mechanical stirring and ultrasonic treatment were in working state during the whole reaction process, and the rotational speed and power remained unchanged. The reacted suspension was filtered and the precipitate was cleaned with anhydrous ethanol.

(4)The precipitates are dried in a drying box and then placed in a tubular furnace. Tungsten oxide powders are obtained by calcination in nitrogen or argon gas flow.

(5)Ultrafine tungsten powders were obtained by reduction of pure hydrogen in tubular furnace at 580-650 ℃ for 2-5 h in the first step, and then at 700-800 ℃ for 2-6 h in the second step.

On the basis of the original liquid-phase chemical method, ultrasonic treatment and preparation of surfactant can avoid the shortcomings of high-energy ball milling, such as easy introduction of impurities and high energy consumption, which greatly improves the purity of the prepared tungsten powders, lays a good foundation for the subsequent sintering of fine-grained tungsten-based alloys with high density, and has a good prospect in the preparation of ultra-fine nano tungsten powders.

• < Prev
• Next >