Mechanism of milling:
Changes in the morphology of powder particles during milling results in the following events.
1. Microforging,
2. Fracture,
3. Agglomeration,
4. Deagglomeration
Micro forging =>
Individual particles or group of particles are impacted repeatedly so that they flatten with very less change in mass.
Fracture =>
Individual particles deform and cracks initiate and propagate resulting in fracture.
Agglomeration =>
Mechanical interlocking due to atomic bonding or vander Waals forces.
Deagglomeration => Breaking of agglomerates
The different powder characteristics influenced by milling are shape, size, texture, particle size distribution, crystalline size, chemical composition, hardness, density, flowability, compressibility, sinterability, sintered density.
Milling equipment: The equipments are generally classified as crushers & mills.
Crushing => for making ceramic materials, oxides of metals; Grinding => for reactive metals such as titanium, zirconium, niobium, tantalum.
Grinding: Different types of grinding equipments/methods are shown in the figure.
