What is Vacuum Coating?

Posted by ryan on November 4th, 2019

The process of Vacuum Coating uses vacuum technology to create an environment such that an atomic or molecular condensable vapor can be deposited as thin films and coatings on the desired surface. Vacuum coating, or physical vapor deposition (PVD), has become a major enabling technology in the field of surface engineering. It is used to deposit both thick and thin coatings of materials that cannot be deposited by any other method.  It is done at a very low temperature and causes negligible atmospheric or water pollution. Vacuum coating allows the deposition of both elemental and compound materials.  Coatings can also be deposited upon a large range of materials, including plastic, fiber and wood.

How does the Vacuum Coating take place?

The process involves using a reactive gas (nitrogen, oxygen, acetylene) in a low-pressure plasma environment, so that compounds of nitrides, oxides, and carbides may be deposited by vacuum coating processes. For example, titanium nitride (TiN) a hard, gold-colored compound is used for coating tools for machining applications, as well as a decorative coating for plumbing and other hardware. Specific properties may be tailored by changing the composition of the coating material and by using layered structures. Both electroplating and vacuum coating can be used as a hybrid coating technology.

 Process of Vacuum Coating

These processes are typically conducted in a vacuum environment with or without the use of plasma (i.e., ionized gas from which particles can be extracted). This adds kinetic energy to the surface (rather than thermal energy) and allows for reduced processing temperature. 

Advantages of Vacuum Coating

The vacuum environment has the following advantages:

• Reducing the particle density of undesirable atoms and molecules (contaminants)so that the mean free path for collision is long
• Providing a low-pressure plasma environment
• Providing means for controlling gas and vapor composition
• Providing means for mass flow control into the processing chamber.

Vapor deposition processes add energy and material onto the surface only, keeping the bulk of the object relatively cool and unchanged. As a result, the surface properties are modified typically without significant changes to the underlying microstructure of the substrate. 

Due to its benefits many scientists and engineers are currently involved in understanding and developing new vacuum (and low-pressure plasma) coating processes and products, that will result in the transfer of that knowledge into production at a commercially viable unit cost. Currently, the global market stands at 87 million.