The protective effect of the coating on the substrate is largely influenced by the bond strength between the coating and the substrate.

The bond strength is not only related to the surface state of the substrate, the composition of the surface material and the density of the material itself, But also the shrinkage stress, the surface tension, the crystallinity and the volume of polar functional groups in the coating.

Between the film and the substrate by mechanical bonding, physical adsorption, the formation of hydrogen bonds and chemical bonds, such as the role of diffusion with each other together. The adhesion of these effects, determines the adhesion between the film and the substrate.