What is Surface Pretreatment for Plasma Spraying

       

The surface pretreatment of thermal spray manufacturers is divided into three stages, namely surface preprocessing, surface purification and surface roughening

Surface pre-processing:



One is to make the surface of the workpiece suitable for coating deposition and increase the bonding area;



The second is to help overcome the shrinkage stress of the coating. Some parts of the workpiece are pre-processed accordingly to disperse the local stress of the coating and improve the shear resistance of the coating. Common methods are rounded corners and pre-coated grooves. Rough threading is also one of the commonly used methods for workpiece surfaces, especially when spraying large workpieces.







Surface purification:



Solvent cleaning, lye cleaning, heating degreasing and other methods are often used to remove oil stains on the surface and keep it clean. Commonly used cleaning solvents are: gasoline, acetone, carbon tetrachloride and trichlorohexene. Alkaline cleaning is often used for large repaired workpieces. The base is usually made from sodium hydroxide or sodium carbonate, which is a cheaper method.







Sandblasting roughening treatment: (This is an important pretreatment method for thermal spraying.)



Sandblasting can form a uniform, uneven rough surface on the clean surface, which is conducive to the mechanical bonding of the coating. Using clean compressed air to drive clean sand particles to spray the surface of the workpiece can generate compressive stress on the surface of the substrate, remove the surface oxide film, and cause lattice distortion of part of the surface metal, which is conducive to the physical bonding of the coating. The substrate metal can be sandblasted to obtain a clean, rough and highly reactive surface.



The above is the relevant content introduced by the supersonic spraying manufacturer, and I hope it will be helpful to you.