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The environment quickly corrodes steel structures during use, affecting the structure’s service life and safety performance. Therefore, steel structure anti-corrosion is a critical task.
Why need steel structure anti-corrosion treatment?
- The corrosion of steel in the atmosphere is the result of both electrochemical corrosion and chemical corrosion.
- To exert the anti-corrosion effect of the coating, the paint film and the steel surface must be closely attached. If rust, grease, dirt, and other foreign matter between the substrate and the paint film, it will reduce the anti-rust effect and accelerate corrosion. Therefore, it is essential to carry out surface treatment of steel, anti-corrosion C-shaped steel, and control the roughness of the steel surface before coating.
- According to the principle of interaction between steel and environmental media, corrosion can be divided into chemical and electrochemical corrosion.
- Chemical corrosion refers to the chemical reaction of steel directly with oxygen gas, carbonic acid gas, acid gas, etc., in the atmosphere or industrial waste gas to cause corrosion.
- The corrosion of steel structures causes economic losses and directly affects structures’ safety. Therefore, it is of great economic and social significance to do an excellent job in the anti-corrosion work of steel structure projects.
- To reduce or prevent the corrosion of steel structures, coating methods are mainly used at home and abroad for anti-corrosion. Coating protection is to use the coating of paint to isolate the steel structure from the environment to achieve the purpose of anti-corrosion and prolong the use of steel structures. Life is over.
- The damage caused by the interaction between the steel surface and the external medium is called corrosion (rust). Corrosion reduces the effective surface of the steel, reduces the bearing capacity, and seriously affects the steel structure’s durability.
Steel structure anti-corrosion treatment method:
1. Hot-dip galvanizing
The hot-dip galvanizing anti-corrosion method is mainly used in outdoor steel materials that are heavily affected by moisture. First, the steel structure components are immersed in a molten metal tank and then coated to form a protective layer on the surface of the steel materials, which has an anti-corrosion effect.
The process of hot-dip galvanizing includes the following steps:
Pretreatment: Surface treatment of steel components, including degreasing, derusting, cleaning, etc. This step is the most critical in the hot-dip galvanizing process, and the quality of surface treatment directly affects the quality of the zinc layer.
Pickling: Soak the pretreated steel components in an acidic cleaning solution to remove residual oxides and other impurities on the steel surface.
Soaking: immerse the pickled steel member in the zinc-containing molten liquid so that the surface is coated with a layer of zinc with uniform thickness. The time and temperature of this step should be well controlled to ensure the quality of the zinc layer.
Cooling: Take out the galvanized steel components, and after cooling, they can be further processed, such as painting, etc.
2. Anti-corrosion painting
The anti-corrosion painting method mainly treats indoor steel materials. It especially forms a protective film by coating special anti-corrosion paint on the surface of steel structures to prevent chemical reactions between steel materials and the external environment and avoid steel corrosion.
The following are the specific steps of the painting:
Surface treatment: First of all, the surface of the steel structure needs to be treated to remove surface dirt, rust, an oxide layer, and other substances to ensure that the surface of the steel structure is smooth, flat, and clean. Surface treatment methods include sandblasting, mechanical cleaning, chemical cleaning, etc.
Primer treatment: After surface treatment, a layer of primer must be applied first to increase the adhesion and durability of the anti-corrosion coating and, simultaneously, provide a certain amount of anti-corrosion protection.
Intermediate coating: After the primer treatment, one or more intermediate layers must be applied to improve the steel structure’s corrosion and weather resistance.
Topcoat treatment: After the intermediate coating is finished, it is necessary to apply a topcoat to increase the gloss and aesthetics of the anti-corrosion coating and, at the same time, provide better anti-corrosion protection.
Inspection: After the coating is completed, the layer needs to be inspected to ensure the thickness and uniformity of the anti-corrosion coating. At the same time, it is also necessary to check whether the performance indicators, such as adhesion, hardness, and chemical resistance of the layer, meet the requirements.
What are the coatings for steel structure anti-corrosion?
Fluorocarbon topcoat is a high-performance coating commonly used for surface coating of steel structures. Its main component is fluorocarbon resin, which has the characteristics of weather resistance, chemical corrosion resistance, ultraviolet radiation resistance, and pollution resistance.
The advantages of fluorocarbon topcoats for steel structure anti-corrosion :
Good weather resistance: Fluorocarbon topcoat has excellent weather resistance and can resist the natural environment’s erosion of ultraviolet rays, wind, and rain.
Chemical corrosion resistance: Fluorocarbon topcoat can resist the corrosion of chemical substances such as acid and alkali, making the steel structure stable for a long time.
Good anti-pollution: Fluorocarbon topcoat has a smooth surface, is not easy to attach to dirt, and is easy to clean, making the appearance of the steel structure clean and beautiful.
Good wear resistance: The fluorocarbon topcoat film has high hardness and is not readily subject to abrasion, protecting the surface of the steel structure from damage.
Pleasing aesthetics: Fluorocarbon topcoat has good color stability and gloss, which can make the steel structure look beautiful.
Epoxy zinc-rich paint
Epoxy zinc-rich paint is a steel structure anti-corrosion coating composed of epoxy resin, chlorinated polyethylene, zinc-rich powder, and other materials. Its main feature is to add zinc-rich powder based on epoxy resin, which has high anti-corrosion performance and adhesion and can protect the steel structure from the erosion of the external environment.
The advantages of Epoxy zinc-rich paint for steel structure anti-corrosion :
Epoxy zinc-rich paint is suitable for corrosion protection of steel structures in marine, chemical, petroleum, and other corrosive environments. Its advantages mainly include the following aspects:
Good anti-corrosion performance: Zinc-rich powder is added to epoxy zinc-rich paint, effectively preventing corrosion and oxidation of steel structures, making it have good corrosion resistance.
Strong adhesion: Epoxy zinc-rich paint has good adhesion, can firmly adhere to the surface of the steel structure, and is not easy to peel off.
Good water resistance: Epoxy zinc-rich paint has good water resistance and can be used in water for a long time.
Good weather resistance: Epoxy zinc-rich paint has good weather resistance and can be used for a long time under different climatic conditions.
Polyurethane paint is a high-performance coating with excellent corrosion and weather resistance. Since the steel structure must often be exposed to harsh environments, such as the ocean, high temperature, low temperature, acid rain, etc., using polyurethane paint to protect the steel structure can significantly extend its service life.
Polyurethane paint has good adhesion properties and can be firmly attached to the surface of the steel structure to form a solid protective layer. In addition, polyurethane paint also has good wear and chemical resistance, which can effectively prevent steel structures from being subjected to mechanical wear and chemical corrosion.
When using polyurethane paint to coat steel structures, it is necessary to pay attention to the thickness of the paint film and the uniformity of the coating to ensure a protective effect. In addition, it is essential to choose the type of polyurethane paint suitable for anti-corrosion, such as high-temperature-resistant polyurethane paint used in high-temperature environments or seawater corrosion-resistant polyurethane paint used in marine environments.