An introduction to thermal spraying

Thermal spraying (aka metal spraying) is a surface engineering/coating process that sprays metals, ceramics and polymers onto the surface of another material. It’s widely used to provide corrosion protection to ferrous metals, as well as to change the item’s surface properties, for instance, to improve the wear resistance or thermal conductivity.

Corrosion and wear are a major problem for a long list of industries, so many use a metal spraying process, including:

  • Offshore
  • Oil and gas
  • Marine
  • Tube, pipe, and general fabrication
  • Petrochemical
  • Construction
  • Water supply
  • Sewerage
  • Ship building
  • Aerospace
  • Airside support

Thermal spraying protects and extends the life of structures, equipment and vessels in many hostile environments and situations, where protective surface coatings are vital for longevity. Many will not have to have their first maintenance of the coating before 20 years’ service, even in harsh environments, leading to significant maintenance cost reductions.

There are four main methods of thermal spraying, all of which project small molten or softened particles onto a surface to adhere and form a continuous coating. The temperature increase of the coated part is minimal, meaning heat distortion is rare – a major advantage over hot-dipped galvanising or welding.

Thermal spraying for corrosion control is usually carried out by Flame and Arc spray – they are the least costly and quickest to implement, so are suitable for corrosion protection of larger structures. Plasma and HVOF sprays are used to apply engineering coatings, and are of a higher quality, density, and bond strength.

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PDF icon Corrosion Management Issue 140