# Relative Density of metal powder

1. Apr 12, 2012

How can I determine relative density of solids in powdered form? or in other word... How do you determine relative density of metal powder... Thank you..

2. Apr 12, 2012

### Staff: Mentor

That depends on the powder,the shape of the individual particles and what you do with the powder. If you know the bulk density, multiply it with the density of your metal (as solid object).

3. Apr 13, 2012

Thank you very much for the prompt reply mfb. To be more precise, in my experiment... I would like to determine the relative density of 57 micron (spherical shape) Stainless Steel 316L powder... After poured inside a container, the bulk density is around 3000 kg/m^3. Since the density of 316L powder is 8000 kg/m^3, so the relative density should be 3000/8000 which is 0.375… Is it correct? Regarding your comment, how the shape of individual particle and what I do with the powder will affect the result? Thank you again….

4. Apr 13, 2012

### Staff: Mentor

That looks correct.

Imagine a powder consisting of small cubes of equal size: With good tools, you can arrange them one by one to fill the whole space with the cubes. But if you just fill some container, they will arrange somewhat randomly and have a lot of free space between them. If you then shake this container carefully, they tend to fill some of these spaces and get a higher density.
Now you have three different densities, depending on your handling of the powder.

With spheres, the highest possible density is ~75%.
With irregular shapes, it is often lower, as they can block each other in many ways.

5. Apr 13, 2012

### sophiecentaur

And a mixture of big and small spheres can be more dense than just big spheres. For a reliable answer I reckon you have to measure samples and keep checking that the mix is consistent between batches.

6. Apr 16, 2012