In the process of copper smelting, the content of impurities must be controlled to make the finished powder have good fluidity and high conductivity. Normal operation is heating to a temperature above the melting point in an intermediate frequency furnace or an electric arc furnace. Melting is the most important process before atomization. By controlling the copper smelting process, the bulk density of copper powder can also be reduced.
There are two kinds of atomized copper powder produced industrially: gas atomization and water atomization. The main difference between these two methods is that the atomization media used are different and the pulverizing principle is the same. According to different gas media, it can be divided into air atomization and argon atomization. At the same time, supersonic atomization is used to obtain finer powder. Production practice has proved that the effect of water atomization is better than that of gas atomization, and water atomization is atomization in air or inert gas.
The reduction process is relatively simple, and the reduction temperature is generally 400-600℃ and the time is 60-120min. Under this temperature condition, copper will be sintered naturally, which requires grinding these massive sintered blocks. The newly developed water mist oxidation method needs no reduction step, which shortens the process flow and saves energy.
From the point of view of thermodynamics, copper is unstable in air, so the oxidation of copper powder in air is inevitable, especially in humid environment, the surface of copper powder is easy to absorb water vapor in the air to form a water film. In addition, due to the formation of a thick water film on the surface of the particles, oxygen infiltration is less and oxygen concentration is lower, so it becomes a micro-anode, and a micro-cathode is formed at the convex and concave places where oxygen can easily reach. Therefore, the concentration of copper powder is poor. After antioxidant treatment, the surface of copper powder is adsorbed and covered with a film, which has antioxidant effect and can prolong its service life. Benzotriazole (BTA), soap solution, gelatin and protein hydrolysate all have good corrosion inhibition effect on water atomized copper powder.