What preparation work needs to be done on the workpiece before thermal spraying

Before thermal spraying, proper pretreatment of the workpiece is essential to ensure a good combination of the coating and the base material, improving the quality and performance of the coating. The following are the general steps of workpiece pretreatment before spraying:

1, clean the surface: use solvent cleaning, steam cleaning or ultrasonic cleaning to remove oil, grease, dust and other pollutants on the surface of the workpiece. Cleaning is the foundation to ensure the adhesion of the coating.

2, removal of oxide layer and rust: use mechanical methods (such as grinding, polishing), chemical methods (such as pickling) or electrochemical methods (such as electrochemical polishing) to remove the oxide layer and rust on the surface to expose a clean, smooth metal surface.

3, surface coarsening: through sandblasting, grinding, rolling and other methods to increase the surface roughness of the workpiece, in order to improve the mechanical bonding force of the coating and the matrix. Appropriate roughness can provide a larger contact area and promote the adhesion of the coating.

4, preheating: in some cases, preheating the workpiece can reduce thermal stress and improve the bonding strength of the coating and the substrate. The preheating temperature should be adjusted according to the coefficient of thermal expansion of the workpiece material and the coating material.

5, matrix protection: for the non-spraying areas or sensitive areas of the workpiece, shielding materials should be used to protect, to prevent the spraying material attached to these areas, affecting the performance or appearance of the workpiece.

6, inspection: After the pretreatment is completed, the surface of the workpiece should be carefully checked to ensure that it meets the cleanliness and roughness requirements before spraying. Any untreated contaminants or inappropriate surface conditions can affect the quality of the coating.

7, drying: ensure that the surface of the workpiece is completely dry, to avoid moisture affecting the adhesion and performance of the coating.

These pre-treatment steps help ensure high quality and bond strength of the thermal spray coating, thereby improving the performance and service life of the workpiece. Different workpiece materials and spraying processes may require specific pretreatment methods, so in actual operation, the appropriate pretreatment scheme should be selected according to the specific situation.