Top-down approach

1
Top-down approach

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• ???

2
Grinding

• ??
• m ? to 10 cm ??
• Jaw crusher
• Gyratory crusher

3
Grinding

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• 10 cm to 1 cm ?? Crushing roll

4
Grinding

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• 10 cm to 1 cm ?? Hammer mill Roller mill

5
Grinding

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• 1 cm to 10 micron ?? roller mill, jet mill, ball
  mill, vibration mill, planetary mill

Low temperature increasing
??ball???????
6
Grinding

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• 1 cm to 10 micron ?? roller mill, jet mill, ball
  mill, vibration mill, planetary mill

40-50 fill, several g
7
Grinding

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• 10 micron to 1 micron ?? ????????, vibration
  mill, planetary mill

8
Surface charge distribution

• The distributions of ions and counter ions are
  controlled by
• Coulomic force or electrostatic force
• Entropic force or dispersion
• Brownian motion
• Inhomogenous distribution
• double layer structure
• separated by the Helmholtz plane

9
Fig 2.14
10
Van der Waals attraction potential

• The sum of the molecular interaction for all
  pairs of molecules
• weak force and becomes significant only at a very
  short distance
• agglomeration of nanoparticles the combination
  of van der Waals force and Brownian motion
• Prevent agglomeration electrostatic repulsion
  and steric exclusion

11
Electrostatic repulsion stabilization
Fig 2.18
12
Steric exclusion stabilization

• Also polymeric stabilization
• Widely used in stabilization of colloidal
  dispersions
• thermodynamic stabilization particles are always
  redispersible
• high concentration can be accommodated
• not electrolyte sensitive
• suitable to multiple phase systems

13
Polymeric stabilization
Fig 2.21
14
Gas phase particle formation
15
Gas phase particle formation, CVD
16
Gas phase particle formation, CVD
17
Gas phase particle formation, CVD
18
Formation of particles in solutions
19
Formation of particles in solutions
20
Formation of particles in solutions, chemical
methods
21
Formation of particles in solutions, physical
methods