Arc Ion Coating
PVD-- physical vapor deposition
One form of physical vapor deposition (PVD coating) is arc ion coating. The history of PVD coating started using arc technology, which has its origin in arc welding.
The metal to be evaporated is placed as solid block (target) against the inside of a vacuum chamber. A glow discharge is ignited and runs on the target, leaving a footprint. Small spots of a few μm diameter target material are evaporated. The movement of the arc can be guided by magnets.
The evaporated ionized material is used as plasma coating on a product which rotates inside the vacuum chamber. Arc coatings are used as tool coating and component coating.
Examples of coatings
Examples of arc coating are TiN, AITiN, AICrN, TiSiN, TiCN, CrCN and CrN coating
Schematic view of a PVD arc process.
The characterized of Arc coating technology:
High deposition rates (1~3 μm/h) High ionisation, resulting in good adhesion and dense coatings As the target is cooled, little heat to the substrate is generated, even coating at temperatures below 100℃ is possible Several compositions of metals can be evaporated, leaving the remaining solid target unchanged in its composition. The cathodes can be placed in any position (horizontal, vertical, upside down), which makes flexible machine design possible.
The main disadvantages of arc coating technology:
Limited kind of target materials - metals only (no oxides) - which do not have a too low evaporation temperature Due to the high current densities some amount of the target material is ejected as small liquid droplets.