Factors Affecting the Coating of Rectangular Tube

Rectangular tube is made of Q235 hot-rolled or cold-rolled strip or coil as the base material by cold bending process and then high-frequency welding made of square cross-sectional shape and size of the section steel. It is widely used in construction, machinery manufacturing, steel construction projects, shipbuilding, solar power generation brackets, steel structure engineering, power engineering, power plants, agricultural and chemical machinery, glass curtain walls, automobile chassis, airports, etc.

In the process of rectangular tube application, in order to prolong its service life, manufacturers will generally coat the surface of the rectangular tube with a protective film to reduce the loss caused by corrosion. So what are the factors affecting the rectangular tube coating?

1、Environmental media

Rectangular tube passivation film in thermodynamics belongs to the sub-stable structure of the inhibition, it plays a protective role in the environment of the media. However, regardless of the environment in which it is used, it must be cleaned regularly to remove the harmful substances attached to the surface.

2、Chloride ion

Chlorine ions are extremely harmful to the rectangular tube coating, and we must strictly control the content of chlorine ions in the passivation solution during the passivation process on the surface. Many passivation chemical materials have limited requirements for chloride ions, and the water used in the configuration of passivation solution and cleaning water also has strict water quality requirements for chloride ions to ensure that the finished passivation does not contain chloride ions.

3、Intrinsic factors

Rectangular tube with low nickel content passivation performance is low, so the martensite content and the content of chromium and nickel on the surface of the rectangular tube passivation performance has a great impact.

4、Cleanliness

The smoother the surface of the rectangular tube the lower the roughness the more difficult it is to have foreign objects attached, corrosion is also reduced to a minimum, so the rectangular tube surface to try to use the finishing process. In addition, the cleaning after passivation should also be carried out carefully, so that the residual acid can promote the anodic reaction, protect the integrity of the film layer and ensure that the surface corrosion resistance is enhanced.