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Particle Characterization
The Institute of Materials Processing uses many different methods
and types of equipment to determine the size and shape of a particle.
Listed below are some of the methods used and a description of
the mechanism for determining either particle size or shape.
Sieve Analysis
Definition: One of the most fundamental methods
for determining particle size is a sieve analysis. This method
involves passing the material being sized through openings of
a particular standard size in a screen. The particle-size distribution
is then reported as the weight percentage retained on each of
a series of standard sieves of decreasing size and the percentage
passed of the finest size.
Equipment: Large assortment of screens available
for sieving. Have Ro-tap for doing large (up to 100 kg) sample
size as well as Sonic Sifter for small (2g) samples.
Particle Size Analysis
Definition: The lineal dimension of a particle as
determined by various analytical methods.
Equipment: Leeds & Northrup Microtrac - laser based method for determining particle size.
Sample is put into solution in an aqueous fluid.
Laser intensity through the turbidity is used to determine material
and particle size. The range of particle size is from
700 to 1 uFm.
Micromeretics Sedigraph 5000ET - x-ray based method for
determining particle size. Sample is mixed with a viscosity specific
fluid which allows the particles to go into solution while being
stirred with a magnetic stirrer. X-ray intensity is used to determine
the settling rate and to calculate the particle size distribution.
Normally used for characterization of spherical particles between
100 and 0.3 uFm in size.
Surface Area Analysis
Definition: Measurement of the exposed external
area of a particle.
Equipment: Micromeretics FlowsorbII 2300
- the measurement of surface area of a material is made by detecting
the amount of nitrogen given off after absorption, considering
one atomic layer of nitrogen adsorbed. Normally used for characterization
of non-spherical and porous particles. Morphology Definition: Particle shape.
Equipment: SEM and image analysis can be used to
define particle shape. Particle shape can be documented with a
microphotograph. Particle shape can be quantified by using image
analysis in conjunction with SEM. The image analysis unit has
the capability to generate an array of chords across the particle
to arithmetically define the shape of the particle.
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