Title: Top-down approach
1Top-down approach
2Grinding
- ??
- m ? to 10 cm ??
- Jaw crusher
- Gyratory crusher
3Grinding
- ??
- 10 cm to 1 cm ?? Crushing roll
4Grinding
- ??
- 10 cm to 1 cm ?? Hammer mill Roller mill
5Grinding
- ???
- 1 cm to 10 micron ?? roller mill, jet mill, ball
mill, vibration mill, planetary mill
Low temperature increasing
??ball???????
6Grinding
- ???
- 1 cm to 10 micron ?? roller mill, jet mill, ball
mill, vibration mill, planetary mill
40-50 fill, several g
7Grinding
- ????
- 10 micron to 1 micron ?? ????????, vibration
mill, planetary mill
8Surface 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
9Fig 2.14
10Van 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
11Electrostatic repulsion stabilization
Fig 2.18
12Steric 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
13Polymeric stabilization
Fig 2.21
14Gas phase particle formation
15Gas phase particle formation, CVD
16Gas phase particle formation, CVD
17Gas phase particle formation, CVD
18Formation of particles in solutions
19Formation of particles in solutions
20Formation of particles in solutions, chemical
methods
21Formation of particles in solutions, physical
methods