Objectives:
1. To analyse the different size and shape of particles
under microscope.
- To describe the distribution particle size and shape.
Introduction:
There are several methods to analyse the
size and shape of particles. Microscopic analysis is one of the methods that
can give an accurate result. the diameter, shape, and surface area of the
particle can be determine in this analysis. In this experiment, different sizes
and shapes of particles are analysed which include the analysis of 355 µm, 500 µm, 850 µm, lactose and sand
with various sizes. During the translation to a circle or spherical-equivalent
diameter, some
batches of samples may differ by such a small amount that this difference is
lost. The shapes of the particles are drawn at the end of the experiment.
Sand is composed of loose, finely grained
minerals that are the product of chemical and mechanical decomposition of rocks
over long periods of time. These minerals include quartz (the most common
mineral) with traces of mica, feldspar, and magnetite. Sand consists mostly of
quartz because other common minerals weather away to sizes smaller than sand,
and quartz does not Sand consists of particles consisting largely of quartz
grains between 0.02 mm and 2.00 mm in diameter. Fine sand is defined
as particles between 0.02 mm and 0.2 mm and course [sic] sand as
those between 0.2 mm and 2.0 mm." Sand is very important in the
making of glass, certain types of mouldings and sand blasting.
Methods
1. By using a microscope, 5 samples of
different types of powders are analysed based on the size and shapes of given
particles.
2. The samples are examined using the magnification of 4X10, followed
by 10X10.
3. The shapes of particles are sketched and
the overall shape of particles of each powder is described.
Observations:
355 µm sand
Characteristic:
same size, small, irregular in shap
4 X 10 magnification
500 µm sand
Characteristic:
almost same size, a bit larger than 355 µm, irregular in shape
4 X 10 magnification
850 µm sand
Characteristic:
particles at upper position looks larger and looks smaller at lower position,
largest size among all sands, irregular and no fixed shape
4 X 10 magnification
10 X 10 magnification
Various sizes
sand
Characteristic:
different sizes, overall smaller than 850 µm, irregular in shape with different
edges and sides
4 X 10 magnification
10 X 10 magnification
Lactose
Characteristic:
almost same size, very small size, round or irregular in shape
4 X 10 magnification
Questions:
1. Describe various statistical methods that can be used
to measure the diameter of a particle.
The statistical methods that can be used to measure
the diameter of a particle include Martin's diameter (M), Feret's diameter (F),
Projected area diameter (da or dp), longest dimension,
perimeter diameter and maximum chord.
Martin's diameter (M) is the length of the line which
bisects the particle image. The lines
may be drawn in any direction which must be maintained constant for all image
measurements. Besides, Feret's diameter (F)is the distance between two tangents
on opposite sides of the particle, parallel to some fixed direction. Next,
projected area diameter (da or dp) is the diameter of a
circle having the same area as the particle viewed normally to the plane
surface on which the particle is at rest in a stable position. In addition,
longest dimension is a measured diameter equal to the maximum value of Feret's
diameter. On the other hand, perimeter diameter is the diameter of a circle
having the same circumference as the perimeter of the particle.
Last but not least, maximum chord is a diameter equal
to the maximum length of a line parallel to some fixed direction and limited by
the contour of the particle.
2.
Name the
best statistical method for every sample that has been used.
For every sample, the best statistical method is Feret’s and
Martin’s diameter. This is because they give the average diameter over many
different orientations to produce a mean value for each particle diameter. This
will give a more accurate value of average diameter as the average value of
diameter in more orientation is taken. Electron microscope is used to analyze
the orientation and shape of the 3D image.
Discussions:
From this experiment, we know that
microscopy method is a good technique to characterize particle size, shape and
volume distribution. From the results, we found that the overall shape of the
sand is asymmetrical. There are 3 main methods to determine the particles’ size
which are Martin's diameter, Feret's diameter and projected area diameter.
Martin's diameter (M) is the length of the line which bisects the particle
image. while Feret's diameter (F)is the
distance between two tangents on opposite sides of the particle, parallel to
some fixed direction.
Besides, projected area diameter (da
or dp) is the diameter of a circle having the same area as the
particle viewed normally to the plane surface on which the particle is at rest
in a stable position .The
ability to analyze and characterize particle size and shape can significantly
improve the manufacturing efficiency and product performance.
All these methods only consider the 2 dimensions despite the three
dimensions of the particle, thus it is inaccurate for unsymmetrical particle.
During the experiment, different types of sand are put on slide to be observed
using a light microscope. To avoid agglomeration, the sand should be spread
evenly and present as a thin layer so that the observation will not be
affected.
From the results, all the sand has small size and irregular shape. Some lactose particles have round shape and
some are irregular in shapes. However, they are smaller than sand particles in
size.
Conclusion:
Sands of different types have different size and shape which can be
analyzed through a light microscope. The overall distribution of shape and size
of this particle which are asymmetrical and irregular can also be
determined.
MICROSCOPE IMAGES
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