What requirements should the surface of the workpiece to be sprayed meet?

       (1) The surface of the substrate should be in a "purified" state. All oil dirt and scaling should be removed, especially attention should be paid to thoroughly remove oil dirt from oil holes, keyways and sand holes on the workpiece.



    (2) The surface of the substrate should be in a "roughened" state. The surface of the substrate to be sprayed must be "roughened", except when the "as-sprayed" coating is used directly.

    (3) The surface of the substrate should be in a relatively "soft" state. This is to increase the degree of plastic deformation of the micro-domain when the sprayed particles hit the surface of the substrate, so as to improve the bonding strength of the sprayed coating and the substrate. To this end, the original hardened layer on the surface of the substrate should be removed, such as chrome-plated layer, heat treatment hardened layer, etc.

     (4) The matrix should be in a state of low stress as much as possible. Relieve stress as much as possible, debunk sharp corners, and remove burrs.