Thermal Spraying

Popular in the 1990s, thermal spraying processes form a continuous coating by melting the consumable material (target) into droplets and impinging these droplets on the substrate. The mechanism of bonding to surface in thermal sprayings is the same as platings, both mechanical interlocking and atomic interaction, with the shear strength around 7 MPa (10 ksi). The thickness of the coatings may range from 25 um to 2.5 mm (.001 – .1 in). In practice, the thermal sprayings are capable of competing with platings and paintings for atmospheric corrosion resistance in water tanks, TV towers, bridges, and other large steel structures.

Some common thermal spraying processes, including Flame Spraying (FLSP), Plasma Arc Spraying (PSP), Electric Arc Spraying (EASP), Detonation Gun (d-Gun), and High-velocity Oxy/Fuel (HVOF), are briefly discussed as follows.

Flame Spraying (FLSP): FLSP was the first thermal spraying process. It use 2760 Deg C (5000 Deg F) oxyacetylene flame to melt the targets which may be powders, rods, or wires.

Plasma Arc Spraying (PSP): Similar to flame spraying, PSP however produces 16,650 Deg C (30,000 Deg F) heat for melting powders and yet the surface temperature of the substrate rarely exceeds 150 Deg C (300 Deg F). PSP is thus more suitable for spraying ceramics on metals and thermoset plastics for building up dimensions or wear resistance. The coatings are usually denser, contain less porosity, and have better adhesion than FLSP.

Electric Arc Spraying (EASP): EASP uses electric arc to melt the motor driven target wires. The melted droplets are then inject to the substrate surface by gas.

Detonation Gun (d-Gun): D-Gun melts target powders in a gun by spark ignition of explosive gas.

High-velocity Oxy/Fuel (HVOF): Executing in a combustion chamber, HVOF uses oxygen, hydrogen, and a fuel gas, e.g., methane, to melt the target powder. Resulting the better control in working environment, the HVOF serve the same function as plasma spraying and often have better quality control.

In summary:


Process Target Form Energy Source
Flame spraying (FLSP) powder, rod, wire Oxyacetylene flame
Plasma arc spraying (PSP) powder plasma gun
Electric arc spraying (EASP) wire (motor driven) electric arc
Detonation gun (d-Gun) powder spark ignition of explosive gas gun
High-velocity oxy/fuel (HVOF) powder oxygen, hydrogen, fuel, e.g., methane, combustion chamber


Sinotech offers an exceptionally wide range of secondary processes that are applied to metals formed in hot or cold processes. Sinotech’ Supplier Quality Engineers determine the availability of the process within the metal forming facility, as well as the quality. If the internal secondary processes do not meet Sinotech standards then the processes are carried out in Sinotech-audited and qualified off-site secondary processing facilities. Sinotech has audited, qualified and worked with QS-9000 and ISO certified secondary processing facilities in China, Taiwan and Korea for over 12 years. Sinotech is dedicated to managing your project on-site and delivering parts to you at lower prices but the same quality, service and terms as a domestic supplier.

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