All thermal spraying processes rely on the same principle of heating a feed stock material (powder or wire) and accelerating it to a high velocity and then allowing the particles to strike the substrate surface. The particles will then deform and freeze onto the substrate.
A common feature of all thermal spray coatings is their lenticular or lamellar grain structure resulting from the rapid solidification of small globules, flattened from striking a cold surface at high velocities.
The coating is formed when millions of particles are deposited on top of each other.
These particles are bended by the substrate by either mechanical or metallurgical bending.
For a better comprehension, the following sketches show the different steps of spraying
1 = Fusion
2 = Atomisation
and speed up
3 = Temperature and speed control
Transport of the spraying particles
Impact on the surface
Thermal transfer from particles to substrate
Solidification and contraction of particles
6 = Local fusion