PVD coating applications

PVD coatings for decorative applications
Since the mid 1990s PVD coatings have been established as the high quality surface finish for sanitary and door hardware with many manufacturers marketing coated products with long time guarantees on their appearance.

PVD decorative coatings - Superior to traditional electroplated coatings
PVD ceramic coatings are a better to traditional electroplated coatings as they have superior hardness and wear resistance, do not discolour or tarnish, have reasonably high corrosion resistance and do not suffer under UV radiation.

PVD decorative coatings - Limitations
PVD coatings are by their nature very thin and provide no leveling effect and to reduce the cost in decorative applications the PVD coating deposited is usually even thinner, typically 0.3 microns. When PVD coatings are this thin they do not act as a corrosion barrier; therefore the PVD coating is applied on top of a corrosion resistant nickel or nickel / chromium electroplated coating. The PVD coating supplies the decorative wear resistant finish.

PVD decorative coatings - Colours
PVD coatings can be deposited with a wide colour range. Metals used as target material in decorative PVD processes are zirconium, titanium, chromium, titanium-aluminum alloys and niobium. Ceramic coatings are deposited to increase the hardness of the coating. This is achieved by introducing reactive gases during the deposition process. The most widely used reactive gases for decorative coatings are nitrogen and methane or
acetylene to produce metal-nitride, metal-carbide and metal-carbonitride films. Also oxygen can be used to produce oxides, oxinitrides, etc. The decorative coatings are produced in a certain colour range, depending on the metal-to-gas ratio in the coating and the structure of the coating. Both of these factors can be altered by changing the deposition parameters.

Zirconium is the most widely used target material for decorative coatings in sanitary and door hardware and other applications such as watch cases because of the relatively wide colour range that is possible, ZrCN for example can look exactly the same as gold if the composition is correct.

PVD decorative coatings - Process Control
The process parameters to deposit each colour are stored in software recipes with various different process steps. During the coating process all the relevant process parameters are continuously monitored and controlled by an automatic computer control system. As a result it is possible to achieve excellent coating quality reproducibility.

PVD decorative coatings - Computer controlled coating machines available
Computer controlled PVD coating systems offering high flexibility and reliability are available. Products made of brass, zinc and ABS will all look the same colour no matter when the coatings were deposited.

To find out more about PVD coating machines click here.