chrome containing thermal pray plasma coating on bolts

Plasma coating – a flexible coating method

Plasma coating is a term that refers to several coating applications which use plasma in the process. Plasma is the fourth state of matter and resembles gas the most: it is an ionized gas which consists of ions and free electrons  resulting in no overall electric charge in low pressures or extremely high temperatures. Therefore, plasma coating applications also make us of either low pressure (vacuum coatings) or heat (thermal spray coating).

In this article you will find information on the plasma coating process and other coatings that use plasma, learn whether plasma spray meets your project’s requirements and find companies that carry out plasma spraying and vacuum plasma spraying in Singapore.

The 3 types of industrial coating technologies that use plasma

The most common use of plasma in industrial coating technologies is in thermal spray coatings, also known as plasma spray coatings where plasma is used to heat up and melt the material (powder, liquid, suspension or wire) to be applied as a coating. The thermal spray plasma coating is one of the most flexible industrial coating technologies, for it can use almost any metallic or ceramic substance to coat the surface. Other plasma coating methods include physical vapour deposition (PVD), plasma enhanced chemical vapour deposition (PECVD) and vacuum plasma spray (VPS).

1. Plasma spray coatings

Traditional plasma spray and vacuum plasma spray are the two thermal spray coatings that use plasma in melting the material. Plasma coating has the advantage of allowing extremely high temperatures: therefore, it can be used to coat metal with almost any other metal or ceramic substance. The plasma coating process may involve temperatures up to 16 000°C. The vacuum spray on the other hand uses slightly lower temperatures but takes advantage of low pressure.

plasma coating applied as thermal spray on motorcycle exhaust

Ceramic atmospheric plasma coating is a common heat resistant solution on exhaust and other applications alike.

  • APS – Atmospheric Plasma Spray: APS refers to the most traditional plasma coating applications – thermal spray coating. In this plasma coating process, plasma is the matter that provides the heat source for melting the coating substance. Powder, liquid or wire is directed to the plasma which melts it and projects it to the substrate.
  • VPS – Vacuum Plasma Spray: The VPS application takes place in a low pressure chamber where metal or ceramic powder is is sprayed into hot plasma (about 9500°C) which melts the material and projects the droplets on the object at high speed. The low pressure allows for high speed application without oxidation.  VPS is common on oxidation sensitive materials such as Ti (titanium) alloys.

Both of these coating methods form a well-adhering, hard surface which has properties depending on the coating material. Vacuum plasma spray is used especially when even better adhesion is required and the coating must have higher density.

2. Physical vapour deposition plasma coating

Physical vapour deposition is a coating method which allows applying coatings from a vapour state to a solid film. Also in this process plasma can be used an an energy source. Therefore, even PVD coating can be referred to as a plasma coating.

This plasma coating process consists of evaporation, transportation and condensation, where plasma has a role in the transportation phase. In this case plasma is the collection of charged particles which travel straight lines from source to substrate. This plasma coating is formed when the plasma and reactive gases such as nitrogen become one on the substrate forming a very thin and extremely hard coating such as Chromium or titanium nitride.

3. Chemical vapour deposition (CVD) plasma coating

a camera lense with plasma coating as an anti scratch solution

PECVD coatings are often applied as anti-scratch solutions on optics.

As the name plasma enhanced chemical vapour deposition implies PECVD is another one of the industrial coating technologies that make use of plasma. It it also a way to apply gas phase matter as a solid thin film coating. Here the plasma is controlled by RF (radio frequencies).

Plasma enhanced chemical vapour deposition is a form of CVD coatings, but it uses lower operating temperatures than the most CVD processes. This is also one of the main advantages of PECVD coating. These coatings require heat from 250°C to 350°C where as the standard CVD process is carried out at the minimum temperature of 600°C.

Plasma spray coating services in Singapore – find an applicator

As different kinds of plasma coatings provide an extremely well adhering coating and provide thermal and electrical insulation when ceramics are used, they are becoming more and more popular. In case you are looking for a plasma spray coating service, do not hesitate to contact us. Our international network of plasma coating specialists is at your disposal! Simply send us an email or use our free quoting service via the “request a quote” button at the bottom of this page.

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