What are the requirements for the performance of metal alloy powder in 3D printing?

wallpapers Industry 2021-06-24
What are the requirements for the performance of metal alloy powder in 3D printing?
There are already many metal alloy powders that can be used for 3D printing in today's society. So, to meet the material requirements of 3D printing, what conditions need to be met by metal alloy powders?
1. Purity
Ceramic inclusions will significantly reduce the performance of the final product, and these inclusions generally have a higher melting point, which is difficult to sinter and shape, so there must be no ceramic inclusions in the powder. In addition, the oxygen and nitrogen content also needs to be strictly controlled.
2. Powder particle size distribution
Different 3D printing equipment and forming processes have different requirements for powder particle size distribution. At present, the commonly used powder particle size range for metal 3D printing is 15-53μm (fine powder), 53-105μm (coarse powder), and in some cases, it can be widened to 105-150μm (coarse powder).
3. Powder morphology
The morphology of metal alloy powder is closely related to its preparation method. Generally, when a metal gas or molten liquid is transformed into a powder, the shape of the powder particles tends to be spherical, and when a solid state becomes a powder, the powder particles are mostly irregular shapes, and most of the powder prepared by the aqueous electrolysis method is dendritic. Generally speaking, the higher the sphericity, the better the fluidity of the powder particles. 3D printing metal alloy powder requires a sphericity of 98% or more, so that powder spreading and powder feeding are easier to perform during printing.
4. Powder fluidity and bulk density
The fluidity of the metal alloy powder directly affects the uniformity of powder spreading during the printing process and the stability of the powder feeding process.
The fluidity is related to the powder morphology, particle size distribution and bulk density. The larger the metal alloy powder particles, the more regular the particle shape, and the smaller the proportion of extremely fine powder in the particle size composition, the better the fluidity; the particle density is not Change, the relative density increases, and the powder fluidity increases. In addition, the adsorption of water and gas on the surface of the particles will reduce the fluidity of the powder.
The bulk density is the powder mass per unit volume when the powder sample is naturally filled with the specified container. Generally, the coarser the powder size, the greater the bulk density, and the powder with the finer and thicker can obtain a higher bulk density. The impact of density on the density of the metal printed final product is still inconclusive, but the increase in the bulk density can improve the flowability of the powder.

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