The basic bonding strength of the coating is related to the cleanliness and roughness of the matrix. Before spraying, the pretreatment of the basic surface such as cleaning, degreasing and surface roughening is an important step in the spraying process. Because some gasoline, acetone degreasing treatment, with a file, fine sandpaper, Whetstone will remove the oxide layer and the fatigue, to expose the metal color. Then roughening treatment, surface roughening treatment to provide compressive stress, combined with the increased area of coating and the substrate and the purification of the surface stress layer cooling, gear pump, stress relaxation within the coating, it is conducive to the increase of bonding force.

Sandblasting is the most commonly used roughening process, sand with sharp, hard as well, can choose quartz sand, Emery and so on. The fresh surface after rough can easily be oxidized or polluted by environment, so it should be sprayed in time. If placed more than 4h, it should be re treated.

Surface preheating treatment. The temperature difference between the coating and the substrate will cause the coating to shrink and cause the coating to crack and peel. The preheating of the substrate surface can reduce and prevent the above-mentioned adverse effects. But the preheating temperature should not be too high, so as to avoid the oxidation of the substrate surface, and affect the bonding strength of the coating and substrate. Preheat temperature is generally 80~90 degrees, commonly used neutral flame completed.