Aluminum alloy passivation: Due to the effect of the medium, the corrosion products of aluminum alloy die castings form a layer of film, which tightly covers the surface of the aluminum alloy die casting, changing the surface state. As a result, the potential of the aluminum alloy die-casting electrode greatly jumps in the positive direction and becomes a passive state of corrosion resistance.
Visual water film method: During the aluminum alloy passivation operation, put the degreased die-casting part into the rinse water, and then take it out. Observe the surface of the die-casting part. The water film of the clean die-casting part after degreasing distribute and the water film is slowly lost. At the same time of degreasing, when the dirty die-casting part has just taken out, the water quickly flows to the surface of the die-casting part, and there is no uniform water film on the surface. Even if there is water on the surface, it still exists in the form of water droplets.
Wipe inspection method: After the die-casting part is degreasing, rinse with water, and then wait for the surface of the die-casting part to be free of moisture, wipe the die-casting part back and forth with a clean paper towel, and observe whether the paper towel is stained. If there is a stain, it means that the degreasing is not clean. It means that the oil is cleaning.
Tactile method: Put the degreased die-casting part in clean water, rinse first, and then touch the die-casting part with your hands. The degreased clean die-casting part has no greasy surface and is relatively refreshing, while the non-degreased die-casting part will feel greasy and will not refresh with your fingers.
Test inspection method: For aluminum alloy passivation, whether the die-casting part after degreasing is clean, you can put the die-casting part after degreasing and rinsing into the passivation solution for 3-5 minutes to see if there is any color change or color change on the surface of the die-casting part. It means that the degreasing is clean without color change, and it is very likely that the degreasing is not clean.