5 Bonding strength
The bonding strength of ceramic coatings includes the interface bonding strength between the coating and the substrate and the bonding strength of the coating itself. The tensile bonding strength of the coating is generally tested by the tensile method. Of course, the shear strength of the interface between the coating and the substrate can also be tested by the shear test. There are two main reasons why nano-ceramic coatings improve bonding strength:


(1) The release effect of unextended interlayer cracks on the residual stress of the coating;


(2) The flying speed of nano-structured feedstock during the spraying process is about 1/3 higher than that of ordinary powder, which is conducive to improving the bonding strength between particles in the coating and between the coating and the substrate.