Flame spray and plasma spray are established thermal spraying methods used to apply protective and functional coatings, but they differ in process design, performance characteristics, and typical applications.
Understanding the processes
Flame spray is a thermal coating process that uses an oxy fuel flame to melt feedstock materials, typically powders or rods, before propelling them towards a prepared surface. The molten or semi molten particles flatten on impact, forming a coating with moderate bond strength that suits repair, corrosion protection, and dimensional restoration uses.
Plasma spray relies on electrically generated plasma, where ionised gas reaches extremely high temperatures and velocities, allowing a wider range of materials to be deposited. In a thermal plasma spray system, powders are injected into the plasma jet, melted or softened, and projected at high speed to create dense, well adhered coatings.
Key differences in performance and application
The primary distinction lies in energy input and coating quality, with plasma spray offering higher bond strength, lower porosity, and greater material versatility than flame spray. Flame spray equipment is generally simpler and more economical, while plasma spray, like the coatings seen on this example https://www.poeton.co.uk/surface-treatments/thermal-metal-sprays/plasma-coatings, is chosen where demanding thermal, mechanical, or wear requirements must be met.
From an operational perspective, plasma systems require controlled spray booths and additional safety measures due to noise and ozone generation, whereas flame spray can be deployed more flexibly after appropriate risk assessment.
Selecting between flame and plasma spray depends on expectations, material choice, and operating constraints, rather than a universally superior solution across engineering sectors.
