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Surface pretreatment (1)
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- Time of issue:2022-02-24 14:32
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(Summary description)Influence of steel surface pretreatment quality on coating protection performance (1)
Surface pretreatment (1)
(Summary description)Influence of steel surface pretreatment quality on coating protection performance (1)
- Categories:News Center
- Author:
- Origin:
- Time of issue:2022-02-24 14:32
- Views:
Influence of steel surface pretreatment quality on coating protection performance (1)
Surface pretreatment, commonly known as rust removal. The steel undergoes surface pretreatment, mainly to achieve the following three purposes:
1. Clean the surface of the substrate to remove unfavorable factors that affect the bonding performance of the coating, such as moisture, oil and dust;
2. Removing the oxide film and passivation film on the surface of the substrate is surface activation, which is conducive to the close bonding between the coating material particles and the substrate; roughening, increasing the bonding area of the substrate and ensuring that the shrinkage stress of the coating can be limited locally area.
Therefore, rust removal should not only remove the rust on the steel surface, but also remove the oxide scale covering the steel surface as well as the contaminated dust, grease, etc. Colleagues require that the steel surface be formed with a certain roughness through rust removal. The quality of surface pretreatment refers to the degree of removal of rust, oxides, and dirt, that is, "cleanness" and the "roughness" formed on the surface of the steel after rust removal. Now the influence of various factors on the protective performance of the coating is analyzed as follows:
The impact of cleanliness
1. Oxide skin
2. Rust
Rust, commonly known as "yellow rust", is a yellow-brown loose substance. The existence of rust on the steel surface has the most direct impact on the coating film because the general coating cannot penetrate into the rust layer to reach the substrate, which reduces the bonding of the coating to the substrate. ability, thereby reducing the protective ability of the coating.
3. Old paint
4, oil, moisture
2. The influence of roughness
The surface roughness of the steel before coating has a great influence on the protective performance of the coating film, because the surface roughness directly affects the adhesion between the coating film and the steel and the distribution of the coating thickness. The existence of surface roughness can improve the bonding force between the coating and the substrate for the following reasons:
1. The existence of surface roughness increases the surface area of the substrate. For example, the surface area of the steel plate after sandblasting can be increased by 20-60%.
2. The existence of surface roughness can limit the shrinkage stress of the coating and prevent cracks in the coating in local areas.
3. It acts as a "mechanical key".
4. The surface roughness can support part of the force of the coating, reduce sag, and is conducive to painting on vertical surfaces.
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