Plasma spraying is a process used in industries such as aviation, where metal components that will be subjected to very high temperatures, corrosion and wear during their lifetime are protected by the application of a material which is applied to the surface of the component using plasma technology.

This process effectively protects the component from environmental damage and reduces its likelihood of succumbing to wear. It involves injecting and treating particles which are applied via a plasma jet spray to form a protective coating on the treated component.

How the process works

To generate a plasma jet, a gas, usually a mixture of argon and hydrogen, is passed through an electric arc discharge which will be formed in the gap between an anode and a cathode. The energy released by the chemical process heats the gas mixture, converting it to a high temperature plasma. This creates expansion and increases the nozzle speed. When it reaches a speed of 800m/s, the coating material is injected in powder form into the plasma jet, creating molten droplets which are applied at high speed onto the component.

The component must be thoroughly soaked in the plasma jet to ensure that an even coating is applied as any small voids in the material can allow the underlying component to oxidise or develop a weakness once in use.

Preparation is key

This process requires significant preparation in order to achieve the best results. The components to be treated must be thoroughly cleaned prior to the application of the plasma spray, as any grit, rust or particles that remain on the component at the point of spraying could come away later in life, creating a void in the applied plasma spray that could allow oxidisation to develop, weakening the component and shortening its lifetime.

Expert advice

This process involves the use of combustible gases and extremely high temperatures and pressures, and as such, is not appropriate for use by the DIY-er. Many specialists, such as www.poeton.co.uk/standard-treatments/plasma-coatings/ offer a plasma spraying service to businesses and individuals wishing to treat their new components or restore old ones. This ensures that the process will be carried out safely and effectively for best results.

Summary

Plasma spraying is an effective method of protecting metal components from wear and environmental damage but should only be carried out by experts with appropriate safety equipment and protocols.