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PVD Coating

PVD Coating

Date posted: December 7, 2017 // Coating

Physical vapour deposition, more commonly abbreviated to PVD, is a method used in a variety of industrial application to produce a coating or thin film of some material with a desirable property on the surface of a second material, which lacks that property. During the process, the source material transitions between states. Beginning in its condensed form, it is first transformed by intense heat to its vapour phase, and then condensed once again upon contact with the cooler surface of the target material upon which it forms the required film.

To form the required film, the two methods most commonly employed are sputtering and evaporation. However, to create the vapour phase required for PVD coating, there is a number of alternative methods, and which of these should be used in any given operation will be determined largely by the nature of the source and target materials.

In the sputtering process, a plasma discharge is held in place around the target by a magnetic field and acts to bombard the source material, which results in some of it being sputtered into a vapour. The vaporised source material subsequently forms a condensate upon contact with the surface of the targeted object.

Other methods used to vaporise the source material required for use in the PVD coating process include the use of a cathodic arc, a beam of electrons, pulsed lasers, and the heat generated by electrical resistance in a vacuum. All of these act to ablate the source materials, which typically consist of compounds such as the nitrides of titanium, zirconium, and chromium, and more complex metallic salts, such as titanium aluminium nitride.

The applications in which this technology is currently employed are both numerous and diverse in their nature. For example, many of the components used in the aerospace and automotive industries depend upon the use of PVD coating techniques to impart properties, such as resistance to the effects of high temperature, friction, and corrosion. At the other end of the scale, both physical and chemical vapour deposition techniques are being used in a technology known as thin film optics to create surface layers in the nanometre range, and equal to the wavelengths of visible light. Among its many other common uses, thin film optics is used to produce the super-reflective properties of the reflectors fitted in modern car headlights.

Among the more significant advantages of PVD coating is that the process can utilise almost any inorganic source, and even selected organic materials. In addition to being a more environmentally friendly process, the films produced are generally tougher and more resistant to corrosion than those produced by electroplating.