The purpose and method of surface pretreatment of base material

       Before preparing the thermal spray coating, the process methods such as cleaning, roughening, preheating, spraying and combining the bottom layer on the surface of the substrate can be collectively referred to as the surface pretreatment of the substrate.



     The surface pretreatment of the base material is a very important process link in the thermal spraying process. The bonding of the thermal spray coating to the substrate is mainly in the form of mechanical interlocking, or "anchoring effect". The molten or semi-melted powder or particles sprayed on the substrate will impact and deform on the surface of the substrate, and tightly bite the concave and convex parts of the surface of the body to form a coating. The size of this meshing ability has a great relationship with the purification degree and roughening effect of the substrate surface. Therefore, by purifying and roughening the surface of the substrate, improving the activity and surface area of the substrate surface will increase the bonding strength of the thermal spray coating and the substrate and improve the internal stress distribution of the coating.

    Main method:

    (1) Purification treatment. The purification treatment methods include solvent cleaning, electrochemical cleaning, heating cleaning, ultrasonic cleaning, high-pressure jet cleaning, sand blasting, electrochemical cleaning, flame burning, etc.

    (2) Surface preprocessing. Surface preprocessing methods include turning, mechanical grinding, etc.

    (3) Coarsening treatment. The methods of roughening treatment include sandblasting roughening, mechanical processing, etc.

    (4) Substrate preheating. The methods of substrate preheating include furnace preheating, flame preheating, etc.

    (5) Non-sprayed surface protection. Non-sprayed surface protection methods include tape protection, paint protection, metal plate or fixture protection, etc.

    (6) Bonding layer. The bonding bottom layer includes coating bonding primer, spray bonding bottom layer, etc.