Metal powder atomization-The difference between water atomization and gas atomization

 Metal powder atomization

Metal powder atomization refers to the process of crushing molten metal into powder with the help of external force. Water atomization and gas atomization are the most widely used powder-making technologies in the world. When we adopt high-speed airflow to Break the molten metal into particles is called gas atomization; while adopting the high-speed water flow to break the molten metal liquid into particles we call water atomization. During atomization powder making, the metal raw materials are first melted into alloy liquid with qualified composition by an electric furnace or induction furnace, and then injected into the tundish above the atomizing nozzle, the metal alloy liquid will flow through the leakage hole at the bottom of the tundish. When passing through the nozzle, it meets the high-speed airflow or water flow and is atomized into small droplets. The atomized droplets rapidly solidify into alloy powder in the closed atomizing cylinder.

metal powder atomization drawing:

Difference between water-atomized powder and gas-atomized powder

One of the differences between water-atomized powder and gas-atomized powder is that the micromorphology of the two powders is different.

As the heat capacity of gas is smaller than that of water, the alloy is subject to a low chilling degree when using gas atomization. When impacted by the atomizing medium, the alloy liquid atomized into small droplets will not solidify immediately, which gives the alloy liquid time to contract into balls during the falling process, so it is easy to obtain spherical alloy powder. Because the heat capacity of gas is smaller than water, when gas atomization is adopted, the alloy is subjected to low cooling, and when impacted by the atomization medium, the alloy liquid atomized into tiny droplets will not immediately solidify, which gives the alloy liquid time to shrink into balls during the falling process, so it is easy to obtain spherical alloy powder, water atomization is the opposite, due to the cooling effect of water on the atomization into fine alloy droplets, almost in an instant to solidify into alloy powder, which makes those alloys with less surface tension to form the alloy powder, into irregular shapes.

Different atomization media and atomization processes lead to the difference in powder morphology, and the difference in powder morphology also leads to the difference in loose packing density, fluidity, and other properties. The powder produced by the gas atomization method has higher shaking density, good flow ability, and requires fewer additives.

In alloy powder made by gas atomization, the alloy subcooling degree is much smaller than that made by water atomization, so the same chemical composition, using different atomization methods to make the alloy powder metallographic organization will be different.

Using air atomization is suitable for metals such as copper, iron, and carbon steel that are not severely oxidized in the atomization process or can be deoxidized by reduction treatment after atomization. Inert gas atomization can reduce the oxidation of metal liquid and gas dissolution and prevent powder oxidation.

Used to make chromium powder and alloy steel powder containing elements or active metals such as nickel base and cobalt base superalloys.

As one of the main methods to produce metal and alloy powders, Gas atomization powder-making equipment making is widely used in additive manufacturing, the powder metallurgy industry, powder injection molding, surface spraying process, 3D printing technology, and other manufacturing fields. In the future, under the background of expanding the market scale of metal 3D printing materials in aerospace, automobile, navigation, nuclear industry and other fields, the market demand for atomized powder will continue to increase, and the industry has a good development prospect.

Water atomization is mainly used for iron, low-carbon steel, alloy steel, and other low-activity metals. Water atomization is a new technology in the powder metallurgy industry. It has the advantages of a simple process, easy-to-master technology, difficult oxidation of materials, and a high degree of automation, It is widely used in the field of atomized iron powder, copper powder, stainless steel powder, alloy powder, and other nonferrous metal powder making, and is suitable for the production of middle and low-end products that are sensitive to cost.

The water atomization pulverizing equipment has the following characteristics:

1. Most of the metal and alloy powders can be prepared, and the production cost is low.
2. The sub-spherical powder or irregular powder can be produced.
3. Due to rapid solidification without segregation, many special alloy powders can be prepared.
4. The particle size of the powder can reach the required range by adjusting the appropriate process.

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