Titanium: Flowability and rheological characteristics
Rheology and transport properties
The flowability of a powder defines its transport properties in a coating machine. Therefore, the flowability of a specific powder should constantly within a certain range and it should not change too much over different bottles and even lots. This avoids time and labor consuming adjustments when switching powder bottles or powder lots.
To characterize the flowability of metal powders Medicoat AG employs different measurement devices for a number of parameters that influence flowability:
- Powder density,
- Tap density,
- Flowability using the Hall flowmeter,
- Angle of repose.
Only in combination these parameters allow the characterization of the flowability of a metal powder.
Tapped density / tamped density
When determining the tapping density, a powder fill is compacted by impacts. After 3000 impacts, the final volume is considered to be reached. The ratio of bulk density to knock density shows how strongly a powder can be compacted, i.e. how strong the inhibitions are for the formation of a densest packing. This says something about how well the powder particles slide along each other or how strongly this relative movement is hindered - for example by the particle shape.
Flowability test with Hall flowmeter
Measurement of time
In this test, a standardised amount of powder flows through a funnel with standardised dimensions. The time required to do this says something directly about the flowability of the powder. This statement can also be transferred to other flow conditions, although this is not always directly possible.
Determining the angle of slope
This test determines the flank angle of a powder pile with a standardised diameter. The steeper this angle, the greater the powder's tendency to agglomerate and the greater the cohesion of the powder particles.
Rheological powder properties
Contact us for more information on our measurement capabilities of rheological quantities.