Figure 1. The PVD process allows metallic atoms to be deposited on the substrate surface in a very thin and pure layer
Physical vapor deposition (PVD in short) is a coating technique belonging to the branch of vacuum coating technologies. Using PVD it is possible to cover a surface with a solid material like aluminum, a metallic oxide such as titanium oxide (TiOx) or a ceramic material as titanium nitride (TiNx). This would not be feasible to achieve by roll coating due to material thermodynamic instability.
How does Physical Vapor Deposition work?
We vaporize the solid material from a conductive target to deposit it on a substrate in a vacuum environment (vacuum allows metal vaporization and it is also used to reduce gas particle density, limit gaseous contamination and control gas flow).
Material vaporization may be obtained either by thermal heating or by sputtering (material removal by ion or atom bombardment). Sputtering is much more energy efficient as compared to thermal evaporation and it is a versatile technique on the point of material deposition. Sputtering can be used to deposit from pure metals to alloys. In addition, sputter atoms have a higher kinetic energy than evaporated atoms, and this is the reason why coatings produced by this process show an improved performance, that is, better adhesion to the substrate, dense crystallographic structures of excellent quality and uniformity.
How is sputtering obtained?
In the sputtering process argon atoms are injected in the vacuum chamber at pressures typically from 1 to 10mTorr; a dc voltage is produced between the cathode (substrate) to the anode (the coating material) that ionizes argon atoms creating a plasma (a hot gas phase composed by ions and electrons). Due to the dc voltage, the argon ions are accelerated to the anode where they collide removing atoms from the coating material. These atoms travel to the substrate where they eventually settle forming the coating.
What does ARCEO Engineering propose?
ARCEO Engineering enhances the basic dc sputtering system by using a Magnetron Sputtering one. The advantage of this system is that electrons are confined to an area near the target instead of being attracted to the substrate, in other words, electrons are not able to damage the thin film being created. It also allows more stable plasma with a higher ion density increasing the probability of further argon atom ionization producing a higher bombardment rate into the target, which is translated into a higher material removal rate and therefore, a higher deposition rate of the coating on the substrate.
In this sense, a better coating quality is achieved because impurities “do not have time enough” to be deposited on the substrate surface.
Figure 2. Argon atoms are ionized in a strong magnetic field. They bombard the target causing the target atoms to be ejected toward the substrate and be deposited on its surface. The strong magnetic field near the target causes electrons from plasma to travel in a spiral trajectory along magnetic flux lines preventing thin film damage.
PVD is useful to deposit pure metals, as it is the case for aluminum deposition for heat shield applications or special conductive coating for hydrogen fuel cell bipolar plate applications. In addition, by injecting small amounts of oxygen or nitrogen in the vacuum chamber (reactive sputtering process), compound materials such as titanium oxide (TiOx) or titanium nitride (TiNx) can be deposited. These two compounds have very interesting industrial applications like decoration in indoor/outdoor architecture for titanium nitride (TiNx) and self-cleaning for titanium oxide (TiOx).
Our PVD-Produced coatings
To learn more about ARCEO Engineering PVD-produced coatings, follow the links below:
Aluminum thin layer on aluminum-silicon coated steel for increased thermal efficiency and for heat shield applications in industries such as pharma (pipe cladding) and domestic and industrial ovens (ShieldArceo).