Preparation process of film

Substrate pretreatment

The substrate used in this experiment is aluminum alloy. Before spraying the paint, the surface should be sandblasted. The specific sandblasting process is as follows: 

(1) The size of the sand used for sandblasting should be uniform, and the particle size should be around 1mm; 

(2) The air pressure at the outlet of the sandblasting machine should be kept at 0.5-0.55MPa, the nozzle is 20-30cm away from the sample, and the spraying angle is 45-80 degrees;

 (3) The metal surface after sandblasting needs to be completely exposed to gray-white metallic luster, and there should be no loose, floating rust and oxide film, let alone oil stains and spots; 

(4) After sand blasting, use a brush or high-pressure air gun to remove dust and seal the sample. It should be painted in a short time. Small parts can be hidden in the baking room to prevent corrosion. 

Paint spraying process

This experiment adopts compressed air spraying and is completed by myself. The specific spraying process is as follows: 

(1) Use a Spray Gun to spray, and the viscosity of the paint is controlled at 18-24s; 

(2) The air pressure of the Spray Gun is controlled at 0.3 -0.5MPa;

(3) The direction of the paint flow from the Spray Gun should be kept perpendicular to the surface of the substrate, and the distance between the two should be controlled at 25-40cm; 

(4) When spraying, the Spray Gun can move up and down, left and right, preferably at a constant speed of 10-12m/min;

(5) When spraying, the surface temperature of the aluminum alloy plate should be lower than 40°C, and the surrounding air humidity should be kept at 30-60°C.

Baking process of paint film

After the paint is sprayed, let it stand at room temperature for a while, and then bake it in an oven for 4 hours to facilitate its film formation. The specific baking process is as follows: 

(1) After the paint film is sprayed, it should be placed at room temperature for 10-20 minutes; 

(2) Then put the sample into the oven, set the desired temperature, and record the time to cure the paint film; 

(3) When the curing is completed, do not take the sample out of the oven immediately, but place it inside for a period of time, and then take it out after the temperature in the oven drops