Metal powders for 3D printing are typically made of aluminum, stainless steel, titanium, or cobalt chrome. They are used to create intricate 3D parts and components for a wide range of industries. Metal powders for 3D printing can be used in a variety of processes, including laser sintering, binder jetting, and direct energy deposition. Depending on the desired application, the metal powder needed to complete the 3D printing job may vary.
Printing is very important consumables; I do not know if you also have such a question: how is metal into powder?
Now, when it comes to 3D printing, we must be familiar with it. Our column has also introduced a lot of 3D printing applications before, such as printing houses, Bridges, etc. Today, we will talk about —— metal powder, an important material used in 3D printing.
According to the preparation process, metal powder can be divided into reduction method, electrolysis method, grinding method, atomization method, etc. At present, the two most advanced milling processes commonly used are the argon gas atomization method and the plasma rotary electrode method.
- Argon gas atomization method
Argon atomized legal powder is a pulverizing method that uses the fast-flowing argon airflow to impact the metal liquid, break it into fine particles, and then condense it into a solid powder.
- Plasma rotation electrode method
Plasma state is called the fourth state of material, the plasma rotating electrode atomization (PREP) powder process can be simply described as: the metal or alloy into the electrode, since the extreme of the coaxial plasma arc heating source melting liquid film, liquid film under the action of rotating centrifugal force is high speed form droplets, melting droplets and atomization indoor inert gas (argon or helium) friction, further broken under the shear stress, then melt under the action of surface tension rapid cooling solidification into a spherical powder.
The metal powder produced by the plasma rotating electrode method has the following advantages: high spherical degree, clean surface, good fluidity, high loose density, so good powder uniformity, printing products cause high density; low particle size, narrow particle distribution, low oxygen content, less / no spherization and agglomeration, good melting effect, high product surface smoothness, and uniformity of holes and cracks, caused by hollow balls.
What are the performance requirements of 3D printing for metal powder performance?
- Purification
Ceramic inclusions can significantly reduce the performance of the final assembly, and these inclusions generally have a high melting point, difficult to sintering, so the powder must be free of ceramic inclusions.
In addition, oxygen and nitrogen content also need to be strictly controlled. At present, the powder preparation technology used in metal 3D printing is mainly atomization method, powder has a large specific surface area, easy to oxidation, in aerospace and other special application fields, the customer requirements are stricter, such as superalloy powder oxygen content of 0.006% -0.018%, titanium alloy powder oxygen content of 0.007% -0.013%, stainless steel powder oxygen content of 0.010% -0.025%.
- Powder particle size distribution
Different 3D printing equipment and forming processes have different requirements for powder particle size distribution. At present, the common powder particle size range of metal 3D printing is 15-53 m (fine powder) and 53-105 m (coarse powder), which can be relaxed to 105-150 m (coarse powder) on some occasions.
3D printing is mainly divided by metal printers with different energy sources, with 15-53 m powder as consumables and electron beam as energy source for 53-105 m coarse powder; for coaxial powder printers, powder of 105-150 m can be used as consumables.
- Powder shape
Powder morphology and powder preparation methods are closely related. Generally, when the metal gas or molten liquid into powder, powder particles tend to be spherical, from solid state to powder, powder particles are mostly irregular shape, and most of the powder prepared by aqueous solution electrolysis is dendritic.
In general, the higher the sphericity, the better the mobility of the powder particles.3D printing metal powder requires the ball to be more than 98%, making it easier to print and deliver powder.
- Powder fluidity and loose loading density
Powder fluidity directly affects the uniformity of powder laying and the stability of powder delivery process in the printing process.
Fluidity is related to powder morphology, particle size distribution and loose pack density. The larger the powder particles, the more regular the particle shape, and the smaller the proportion, the better the mobility; the same particle density and the relative density increases. In addition, the particle surface adsorption of water, gas and so on will reduce the powder fluidity.
Pine density is the powder sample naturally filled with specified container, unit volume of powder mass, in general, the coarser powder grain size, the greater the loose density, thickness of the powder can obtain higher loose density, loose density for metal printing the density of the final product is not determined, but loose density increase, can improve the flow of powder