Although the processing principles are the same, the physical properties of water atomized metal powder and gas aromatized metal powder have great differences, especially for shape. Gas’ heat capacity is smaller than water. So in the use of aerosol, chilling for metal is lower. If it is attacked by atomizing medium, the tiny droplets of liquid metal will not be solidified immediately. It gives the alloy droplet some contraction time to the ball, so it is easier for metal powder exporter to obtain the spherical alloy powder.
Situation is the opposite of water atomized water atomized into tiny droplets of metal chilling, almost in an instant, solidified into a metal powder, which makes the surface tension of the alloy metal powder was The potato-shaped or irregular in shape, only the surface tension of the alloy, such as nickel-based alloy can be made spherical metal powder. Superheat by adjusting the atomization parameters and alloy liquid atomization, water atomization can be made spherical metal powder, to meet the needs of the thermal spraying. For tubular welding wire intermediate powder, no special requirements on the shape. It is more suitable for water atomization.
Water atomization or aerosolization, the metal powder to produce the chemical composition does not differ because of different production methods. Metal powders produced by gas atomization, the alloy undercooling than using much small mist overtaken by the same chemical composition and microstructure of the metal powders made by atomization methods will be different.
The oxygen content of metal powder with the metal itself, the oxygen content of oxygen in the sensitivity and atomization environment. If itself is very sensitive to oxygen in the atomization is not only want to take measures best when melted by vacuum melting. For most metals, adopt measures to reduce contact with oxygen in the atomization, we can achieve the purpose to reduce the oxygen content in the metal powder. Aerosolization using nitrogen as the atomizing medium, large amount of nitrogen is full of atomization, the atomization zone oxygen expelled out, they are able to protect that very little oxidation of the droplets in the atomization and cooling.
When a furnace of molten liquid metal is atomized into a metal powder, it is the surface area increases the atomization of the moment countless times, in other words, it combines with oxygen to the area increases, and more of the metal surface is exposed to the atomizing environment. Therefore, water atomization, if you do not take measures, is not to avoid the oxidation of the alloy droplet. In order to water atomization, allowing atomization environment less oxygen or oxygen-free, must first be atomized cylinder seal, will cut off from the atomization environment with the surrounding environment. Secondly, it should exclude oxygen in atomization tube. Finally, in the atomization process has been to maintain an anaerobic or hypoxic atomization environment until nebulization. All the metal droplets are solidified into silicon powder.
Production costs of per kilogram of gas atomized metal powder are higher than water atomized metal powder. In the actual calculation, a bottle of nitrogen can makes about 10 to 20 kilograms of metal powder. And one kilogram of alloy powder cost five to ten RMB for atomizing medium. In water atomization, the atomizing medium mainly consumes electricity in the running pump. In one atomization time, one kg of alloy powder spent 0.5 RMB in electricity cost. For this reason, coast of gas atomized metal powder is much expensive than water atomized metal powder in the market.