Nanometer Tungsten Powder Obtained by Ultrasonic Spray Heat Conversion Method

In recent years, due to its excellent electrical conductivity, heat dissipation and expansion coefficient, it is used in large scale integrated circuits and high power microwave devices to make substrate, hot pillow chimera, package connector and heat dissipation element. Because of the high thermal conductivity and heat resistance of the tungsten copper alloy, the power of the microelectronic devices is greatly improved, and the device can be miniaturized. The expansion coefficient can match well with the silicon, gallium arsenide and other semiconductor materials in microelectronic devices, so it is an ideal packaging material.

At present, the tungsten powder with a particle size of 3~5 μm is used in all countries in the production or development work. The tungsten material made of this tungsten powder has grown from (3~5) μm to (200~400) μm, about 60~80 times that of the original tungsten grain. Such coarse tungsten grains obviously reduce the mechanical properties, physical properties and pressure processing properties of pure tungsten materials. In recent years, the use of nanometer sized ultrafine particles (less than 100nm) at home and abroad, the production of ultrafine grain pure tungsten materials and ultrafine grain W-Cu, W-Ni-Fe and other tungsten based alloys has been applied, so the demand for nano tungsten powder has increased dramatically.

The precursor amorphous powder obtained by the ultrasonic spray heat conversion method is used as raw material. The precursor is drained by vacuum ammonia drainage, and then the O-R-III phase change stress dismuting can be made into nanometer sized tungsten powder and blue tungsten powder with an average particle size of 35nm, and the ultrafine tungsten powder is made by hydrogen reduction. The specific process steps are as follows:

(1) Using a high concentration ammonium tungstate water solution, in the ultrasonic spray heat conversion tower, an ultrasonic atomizing nozzle with alpha = 45°C was used to compress the air pressure 3MPa, the hot air temperature 130 ～150°C, the preparation of the precursor amorphous powder with an average diameter of less than 50nm.

(2) Amorphous powder 1.855kg prepared by ultrasonic spray thermal conversion method.

(3) The precursor amorphous powder 1.855kg was placed in a continuous spiral propulsion vacuum furnace and under the vacuum degree 10Pa, at 150°C, 40 minutes. 350°C, 40 minutes. 500°C, 40 minutes. Ammonia discharge and drainage treatment were carried out. The heating rate is 5°C/ min.

(4) In the continuous strong drainage type reduction furnace, the flow rate is 40 to 45ml/ (cm2•minutes) at 400°C, 60 minutes and H2 sections, then reduced to nanometer blue tungsten powder. After the third 0- treatment, nano SAXS powder 1.261kg with average grain size of 35nm can be obtained (35nM).

The above method can be used to continuously produce WO₃ powder, WO_2.9 blue tungsten powder and nano tungsten powder with an average particle size of 33.5nm by continuous large-scale production of nanoscale average particle size 35n. The equipment is simple, the process flow is short, the actual yield is high, and the production cost is low, so it is easy to popularize and apply.

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