Nano Copper powder of Tungsten Copper Electrode Preparation II

Compared with traditional powder metallurgy (PM), tungsten copper electrode nano composite material including powder milling, compacting and sintering process, but due to the characteristics of nano particles, there are some differences between traditional powder metallurgy and nano copper powder preparation.

3. Mechanochemistry

It combined both high energy ball milling and chemical reaction. High energy ball milling has many advantages, such as simple operation, high efficiency, especially suitable for the metal with high melting point, mutually insoluble solid solution system, micro intermetallic compound fabricating and micro metal ceramics composite materials. However, the distribution of grain produced in this way is uneven and it will easily bring in other impurities in the process of ball milling. The researchers uses Mechanochemistry, which smash the mixture of CuN and Na powder and produces Cu and NaCl micro nanocrystaline mixture by solid substitution reaction. Washing the mixture to remove the milled sodium chloride, ultrafine copper powder can be obtained. It can not be neglected that adding NaCl will avoid the mixture burning, and the copper powder will be finer (20-50μm of granularity).

4. γ Ray irradiation - hydrothermal crystallization

The method mainly in the experimental stage, some scholars use Co γ ray irradiation source strong metal ultrafine particles prepared using γ-ray radiation - hydrothermal crystallization method jointly received an average particle diameter of about 50μm of copper nano particles.

5. Liquid phase reduction

In liquid or very close to the liquid state, the raw material can be synthesized directly metal nano powders. The use of inorganic metal compounds in the alcohols (ethylene glycol, diethylene glycol, etc.) in the heating reduction can be prepared mono disperse copper nano particles. The researchers used hydrazine hydrate reduced copper pickled copper, while adding polyethylene polymer protective agent pyrrolidone (PVP) help stabilize the grain to prevent agglomeration, use magnesium Mg as the catalyst reaction, copper obtained a considerable part of condensed matter. However, the methods used hydrazine hydrate is highly toxic, is not suitable to promote production use.

6. Self suspended directional flow

Metal material melts in high frequency power supply heating to the metal droplets in countercurrent sensor electromagnetic field generated by spherical droplets of molten metal suspended in studio and continues to be heated. Meanwhile, the inert gas as a cooling medium is always a constant flow rate passing molten metal droplet surface. When the spherical droplet reaches a certain temperature, the surface of the metal vapor produced in the cooling stream of inert gas is too cold nucleation and subsequently grow up (including a collision with the merger between the particles), the final formation of the desired metal nano particles.

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