Supersonic Thermal Paint Spraying

There are many different types of paint spray gun systems. From airless paint sprayers to electrostatic. All of which have specific uses. Ultimately their primary purpose is to apply coatings to a variety of surface types.

Types of spray gun systems

  • Airless Paint sprayers
  • HVLP paint sprayers
  • Gravity Feed Spray guns
  • High Volume low pressure
  • Air-Assisted Sprayers
  • High Velocity Thermal Spray (HVTS)
  • High Velocity Air Fuel (HVAF)
  • Airless Spray guns
  • Electrostatic spraying
  • Wagner Airless Controlpro

supersonic thermal paint spraying schematic diagram
Supersonic thermal paint spraying schematic.

In this article we’re going to focus on ‘supersonic thermal paint spraying’ or ‘high velocity thermal spraying‘ (HVTS) and explore application types, advantages and disadvantages. It produces strong, uniform coatings with a flame temperature close to the melting point of coating materials, preventing particle overheating and ensuring uniform mechanical coating. HVAF coatings are highly resistant to abrasion, wear and corrosion with their low spray temperature providing excellent protection against cavitation damage.

High Velocity Thermal Spray (HVTS)

HVTS (high velocity thermal spray) application is faster and more cost-effective than weld metal overlay, offering up to 50% savings compared to other technologies. This application method does not require curing time, is not affected by atmospheric conditions and reduces turnaround time by up to ten days. HVTS metal coatings are highly durable and can withstand harsh environments and impact damage. Watch the video below to see the process in action.

High Velocity Air Fuel (HVAF) Thermal Spraying

HVAF (high velocity air fuel) is an improved method closely related to HVOF spray. HVAF coatings create durable, uniform coatings using a high flame temperature near the melting point of coating materials. This prevents overheating of particles and ensures consistent mechanical coating. HVAF coatings are highly resistant to abrasion, wear, and corrosion, and offer excellent protection against cavitation damage due to their low spray temperature.

Propane combustion in compressed air is used to create a high-velocity jet. A heat baffle provides stability while the coating particles are propelled onto the substrate, at faster speeds, lower-temperature coatings have improved wear and corrosion resistance.

High Velocity Oxygen Fuel (HVOF) Thermal Spraying

HVOF (high velocity oxygen fuel) is a protective coating applied to metal components. Flame guns, either hand held or mounted on robotic arms are used in the coating application process. Powder is melted by a flame at 5,000°C and propelled at over 2,300 mph / 3,700 kph or mach 3 (three times the speed of sound). This creates an extremely robust bond between the coating and the substrate. When cooled the coating can be left as it is, re-coated or polished.

Generic technical information

Fuel types

A variety of fuel types are used in HVOF and HVAF such as kerosene, hydrogen, oxygen, propylene and propane. Kerosene is widely available around the world and you can find it at any airport. Propylene and propane are also widely available around the world. Hydrogen/oxygen requires adherence to stricter safety guidelines.

Deposition Efficiencies and Feed Rates

The deposition rates vary depending on the spray gun make an model. The deposit efficiency is an important factor. A difference of just 1% can result in a saving of £10k per month in material costs.

Application types

Supersonic thermal paint spraying is mostly used for the protection of components, vessels and structures from abrasion, erosion and wear. The technology first developed over 100 years ago.

The application of various coatings, includes;

  • Nickel alloys
  • Carbide coatings
  • Low melting point metal spraying
  • Tungsten and Chromium

Used in numerous industries such as;

  • Chemical & Manufacturing
  • Waste-to-energy
  • Biomass plants
  • Oil and gas industries
  • Aircraft industries
  • Turbine industries

Further Reading

Please Share this Article on :