Powder Characterization

Powder characterization includes flow measurements, morphology, particle size
distribution, density and chemical composition. Bettersize PowderPro Series
instruments are mainly used for the analysis of the powder physical properties
by testing items such as angle of repose and fall ,angle of spatula (flat plate
angle) ,bulk and tapped density, dispersibility, voidage and cohesion ,angle of
difference , compressibility , uniformity, flowability Index ,floodability
Index ,sieve size, angle of slide,etc.

What are bulk density, tapped density and compressibility, flowability index?
Bulk density: fill the powder sample into a measuring cup, flatten the top, the
ratio of the powder mass to the volume of the cup is defined as bulk density.
It indicates the mass of the powder that can be added into the vessel per
volume under the normal conditions.

Tapped density: fill the powder sample into a measuring cup; vibrate the cup at
certain amplitude and frequency to remove air from the powders. After reaching
the required vibration time, flatten the sample. The ratio of the powder mass
to the volume of the cup is defined as tapped density. Tapped density indicates
the mass of powders filled into the vessel per volume after excluding air from
the powders. The data of bulk density and tapped density are often used for the
design of vessels, bags, and tanks for powder storage.

Compressibility: it is the ratio of the difference between tapped density and
bulk density to tap density. It shows the degree of volume reduction from bulk
to tap state.

Flowability Index is a set of numerical values obtained by the weighted
summation of angle of repose, Compressibility, angle of spatula, uniformity,
and cohesion. It is used to comprehensively evaluate the flowability of the
powder. The Flowability Index is mainly used to describe the powder flowability
under gravity.

What are angle of repose, angle of fall, angle of difference, and flat plate
angle (angle of spatula)?
Angle of repose: Under the static balance, the angle between the slope of a
powder pile and the horizontal plane is angle of repose. It is measured when
the powders fall to a surface via gravity and form a cone. It indicates the
flowability of the powders. The smaller the angle of repose is, the better the
flowability of the powders.

Angle of fall: After measuring the angle of repose, apply an external force to
the powder pile to collapse it. The angle between the slope of the collapsed
pile and the horizontal plane is defined as angle of fall.

Angle of difference: It means the difference between the angle of repose and
the angle of collapse. The larger the angle of difference is, the better
flowability of the powders.

Flat plate angle: immerse a plane in the powder pile; pull up the plane
vertically, one angle is formed between the slope of the powders on the plane
and the plane. Apply an external force to obtain another angle. The average of
these two angles is flat plate angle. The smaller the flat plate angle is, the
better the flowability of the powders. The flat plate angle is usually larger
than the angle of repose.

How to measure flowability of metal powders?
According to GB1482 and ISO4490, the flowability of metal powders is usually
measured with a Hall flow meter.
The measurement process is:
• Weigh 50g + 0.1g sample;
• Plug the hole in the funnel with the finger;
• Pour the sample into the funnel;
• Quickly remove the finger from the small hole and starting the stopwatch at
the same time (precision 0.2S);
• Wait until the powder sample runs out, and stops the timing immediately;
• Evaluate the fluidity of the metal powder through the time of the 50g powder
passing through the hole.
The standard funnel of Holl flowmeter needs to be calibrated by standard sample
with the flow speed of 40 + 0.5s/50g.

Bettersize has become a significant player in the particle sizing business
since 1995. We provide
particle size instrument, laser diffraction analyzer, laser particle sizing,
particle measurement and etc. Want to know more? Please contact us.

Minimum Order: 1 sets

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