Aluminium powders, especially the flakes with lamellar geometry are used with polymers to manufacture pigments, mastics for metal replacement or repair, heat diffusion, electrical conductivity and EMI shielding, gas and moisture barrier, UV protection and so on.
Aluminium flakes are manufactured from pure aluminium: 99.3 % to 99.7 %. A fine layer of alumina protects the flakes. Powders are produced in different particle forms:
- Flakes of more or less thin shapes with broad to narrow particle size distribution.
- Granular or 3D powder.
Sizes depend on grades, ranging from 0.1 m to 2.0 m in thickness and 0.5 m to 200 m in diameter. D50 is in the order of 4 m to more than 17 m. The aspect ratio is in the order of near 1 to 400 and more. The covering areas of the various grades of flakes are ranging from 0.5 m2/g to 3.5 m2/g. In comparison, the specific area of carbon black is in the order of 30 to 130 m2/g.
- For paints, varnishes and coatings, flakes are coated with fatty acid. They have hydrophobic and oleophilic properties.