Plasma Thermal Spray

The Plasma Thermal Spray process uses the latent heat of ionized inert gas—known as plasma—to generate the high-temperature heat source required to melt and spray a wide variety of coating materials. The most commonly used plasma gas is argon, referred to as the primary gas.

PLASMA EXPLAINED
Plasma is often described as the fourth state of matter. Like solids, liquids, and gases, it has unique properties. When matter is heated to extremely high temperatures, electrons are stripped from atoms, creating plasma—a substance that resembles a gas but conducts electricity. On Earth, plasma occurs naturally in lightning, electrical discharges, aurora borealis, and solar winds.

How does it work

In the plasma spray process, argon flows between the electrode and nozzle of the spray gun. A high-frequency or high-voltage electric arc is struck between them, ionizing the gas stream and forming plasma. By increasing the arc current, the plasma arc thickens and becomes more ionized, boosting both temperature and gas velocity.

When using argon alone, extremely high arc currents (typically 800–1,000 amps) are required to generate sufficient heat to melt most materials. However, this can result in gas velocities that are too high for certain materials with high melting points. To address this, secondary gases—commonly hydrogen—are added to optimize the thermal and electrical properties of the plasma. Once the appropriate gas mixture is established, the coating material, in powder form, is injected into the plasma stream, where it is melted and propelled onto the substrate surface.

Plasma spray advantage

Plasma spraying offers exceptional flexibility and performance benefits:

A broad range of coating materials (metals, ceramics, plastics, composites, and even glass) can be applied.
Capable of producing high-quality coatings, superior to conventional flame or electric arc spraying.
Ideal for spraying refractory metals and ceramics with very high melting points, such as zirconia (ZrO₂), boron carbide (B₄C), and tungsten.
Supports a wider particle size range (5–100 µm), compared to processes like HVOF.
A mature, widely available, and well-understood technology, trusted across industries.

Thanks to its high temperatures and adaptability, Plasma Spray Coating is a proven solution for industries requiring thermal insulation, wear resistance, and corrosion protection in the most demanding environments.

Typical plasma spray coating applications / industry

Aviation – Gas Turbine and Airframe Components
Marine – Anti-Fouling Coatings, Anti-Skid Decking, Propellers, Shafts
Power Generation – Gas Turbine Components and Cases, Hydroelectric Turbine components, Steam Turbine Components, Solid Oxide Fuel Cells
Transportation / Heavy Equipment – Engine and Drive Train Components, Mould Release Coatings
Paper and Printing Machinery – Anilox Rolls, Impression Rolls, Corona Rolls, Boilers, Digesters, Paper Manufacturing Rolls and Components
Petrochemical – Pump Components, Valves, Tank Linings
Metal Processing – Sink Rolls, Extrusion Rolls, Extrusion Dies
Textile Machinery – Stretch-Tow Rollers, Thread Guides
General Industry – Many surface restoration and functional surface applications

Compared to other processes

Some materials, particularly ceramics, require an extraordinary amount of energy to soften and transform into a functional coating. In plasma spraying, these materials—supplied in powder form—are exposed to extreme temperatures of up to 16,500°C within the plasma jet and then propelled at speeds reaching Mach 2 onto the substrate. This combination of ultra-high temperature and supersonic velocity enables the successful deposition of materials that are otherwise very difficult to process.

The inherent versatility and precision control of plasma spraying makes it possible to deposit a wide variety of materials, including metals, alloys, ceramics (oxides and carbides), and cermets. These coatings provide exceptional performance benefits, such as:

Abrasion and wear resistance
High-temperature stability and thermal barrier protection
Corrosion resistance in harsh industrial environments
Electrical conductivity or insulation, depending on the material
EMI (Electromagnetic Interference) shielding
Non-stick or release properties for manufacturing processes
Restoration and repair of worn or damaged parts

Thanks to this adaptability, Plasma Spray Coatings are widely used across industries such as aerospace, energy, automotive, and heavy manufacturing, where components must withstand extreme operating conditions while maintaining reliability and performance.

Thickness