Corrosion Protection Methods for Steel

Corrosion of steel can be caused by material properties, usage environment, and contact media, so corrosion protection methods vary accordingly.

1. Use of Corrosion-Resistant Weathering Steel

Weathering steel contains elements such as phosphorus, copper, nickel, chromium, and titanium, which form a protective layer on the metal surface. It has superior corrosion resistance compared to general structural steel and also has better low-temperature impact toughness.

2. Long-term Corrosion Protection

The metal protection layer is created using metals or alloys with anodic or cathodic protection properties, through methods such as electroplating, hot-dip coating, spraying, chemical plating, and diffusion coating. These methods form a protective layer on the metal surface to isolate the metal from the medium, or use electrochemical action to protect the metal from corrosion. The two main methods are hot-dip galvanizing and hot-spray aluminum (zinc) composite coatings.

3. Chemical Protection Layer Method

This method uses chemical or electrochemical processes to generate a thin film on the metal surface that provides corrosion resistance, isolating the metal from the corrosive medium. Examples include passivation and phosphating treatments for steel.

4. Conventional Coating Method

This method uses coatings, plastics, or enamels to form a non-metallic protective film on the metal surface by brushing, spraying, etc., isolating the metal from the corrosive medium. Steel structures are protected from corrosion using surface coatings. Indoor steel structures or outdoor steel structures that are relatively easy to maintain often use coating methods for corrosion protection, as their protection is not as long-lasting as other methods. The first step of coating construction is rust removal, often using sandblasting or shot peening to remove all oil and rust. The coating should be selected based on the surrounding environment, and different coatings have different tolerances to various corrosion conditions.

The high-performance Mengneng anti-corrosion coatings typically consist of three layers: primer, intermediate coat, and topcoat.

①The primer contains less binder and more powder, forming a rough film with strong adhesion to steel and good compatibility with the topcoat. In highly corrosive environments, zinc-rich primers are usually selected. In less corrosive environments, zinc phosphate primers are typically used. Epoxy zinc-rich primers have the following advantages over inorganic zinc silicate primers: firstly, no need for a sealing coat between the primer and intermediate coat; secondly, they are not sensitive to air humidity, as epoxy zinc-rich primers are usually based on epoxy resin, polyamine, or polyamide curing mechanisms that do not require moisture from the air; thirdly, they can self-repair and have strong adhesion. Currently, epoxy zinc-rich primers are widely used for steel structure corrosion protection.

②The intermediate coat in high-performance coating systems is typically an epoxy red iron oxide coating. The interlocking plate-like red iron oxide effectively blocks the penetration of moisture, oxygen, and electrolytes, providing better barrier protection. Additionally, the red iron oxide in the epoxy intermediate coat extends the time window for topcoat application, improving the performance of the coating.

③The topcoat has more binder and a glossy finish, protecting the primer and resisting weathering. Since most steel structures require prevention of gloss loss and fading, using high-performance topcoats with good color and gloss retention can save significant maintenance costs in the future.

Coating construction requires proper humidity and temperature. The construction environment should have minimal dust, and the surface of the components should not have condensation. No rain should fall within 4 hours of coating. Typically, the coating is applied in 4 to 5 layers.

5. Mengneng Technology

Mengneng Technology is a company specializing in the sales, solution design, and application construction of coatings. The company excels in industries such as EMI, industrial equipment manufacturing, bridge steel structures, petroleum and petrochemical, special gases, thermal power, wind power, and hydroelectric power, with a focus on heavy-duty corrosion protection. Mengneng Technology offers comprehensive services to customers, including recommending suitable paint solutions during the design phase, providing high-quality products and construction services during cooperation, and offering complete on-site technical guidance and excellent after-sales services.