Combination form of thermal spray coating and substrate-mechanical fitting

       Mechanical fitting

 

     Mechanical engagement refers to the mechanical engagement formed by the droplets with a certain kinetic energy that collide with the surface of the roughened substrate and form the protrusions and depressions on the surface. The particles of the coating are connected to the surface, and between the particles and the particles by mutual inlay. Thermal spraying on a surface with a relatively large roughness (such as a surface that has undergone coarse-grain sandblasting or a surface with organic grooves and threads) When the mechanical fit plays an important role.

 

     Experiments show that the bonding strength is 36-41 MPa when nickel-clad aluminum is sprayed on the surface of Ra=0.63um. If the surface is roughened by sandblasting, the bonding strength can reach 45 MPa, which reflects the effect of mechanical fitting to a certain extent. The rougher the surface, the greater the effect of mechanical fitting. At present, quite a lot of people believe that the bonding strength between the thermal spray coating and the substrate mainly depends on the mechanical intercalation between them. In engineering, the surface roughening of the sprayed workpiece has become an essential and important surface pretreatment process.