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Five Things You Should Know About Metal Powder Production

Posted by Alex Barshai on Jun 20, 2017 4:20:28 PM
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In electroplating, powders can be a very bad thing, but sometimes bad can be good. We are going to discuss doing a ‘bad thing’, but doing it consistently well.

 

 

1. There are five typical ways of making metal powders:
  • Melting and atomizing
  • Grinding
  • Vaporization
  • Precipitation
  • Electrodeposition
2. There are two key differences between types of electrodeposited powders: Metals that want to be powders vs. metals that prefer to be plate.  Electrodeposition of a powder can be due to preferred crystal structure, the type of solution and the conditions of that solution which can affect the deposit.  For example, silver from silver nitrate prefers to deposit as powder whereas silver from silver cyanide generally prefers to make plate (assuming equal concentration of silver in solution).

 

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3. Careful control of key parameters can be used to make consistent powders:
  • Metal concentration
  • Deposition time
  • Flow Rate
  • Temperature
  • Current density
  • Additives  

These parameters can affect the particle size, shape, and density.

4. Powders have a very high surface area.  For example, if you take 1 mg of Copper, and make it into a perfect sphere, you will have a sphere of approximately 600 microns in diameter.  If you take that 1 mg of Copper and you split it into 1000 pieces, you will have a 1000 spheres approximately 60 microns in diameter, 10x the surface area of the previous example.  

Another way to increase surface area is to stretch it, or change the shape.  For example, take 1 mg of Copper and stretch it into a long piece of wire, 10 meters long, 4 microns in diameter, having 120x the surface area compared to the original piece of Copper.  

In chemical reactions, an increase in surface area willl generally result in an increase in reactivity.  

5. An increase in surface area of powders can be achieved by changing the shape.  We can make powder deposits under controlled conditions in order to increase surface area. Changing these conditions can lead to the production of very interesting powders which can be dendritic, fern-like structures with very high surface area and reactivity that ideal for a variety of high-tech applications.  

 

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Topics: metal powders, Advanced Metal Powders