One、Physical Anti-Corrosion Coating
The main types of physical anti-corrosion coatings include: iron red anti-rust paint, mica oxide anti-corrosion coating, aluminum powder anti-corrosion coating, glass flake anti-corrosion coating, and stainless steel flake anti-corrosion coating. Iron red anti-rust paint primarily utilizes its fine particles to fill the paint film structure, thereby increasing the density and reducing the permeability of the paint film. In contrast, anti-corrosion coatings based on mica oxide and aluminum powder primarily enhance the sealing and anti-corrosion capabilities of the coating by cutting through capillary pores within the paint film.
II. Chemical Anti-Corrosion Coatings
The materials used in chemical anti-corrosion coatings fall into three main categories: lead-based, chelating agent-based, and non-toxic pigment-based.
The most commonly used component in lead-based anti-corrosion coatings is red lead, which exhibits excellent anti-corrosion properties on industrial atmospheres or steel surfaces with residual rust.
Chelate-based anti-corrosion coatings primarily consist of zinc oxide and thiourea-based compounds. When moisture penetrates the coating film, its strong oxidizing properties enable it to form a protective layer on the metal surface, resulting in passivation.
Non-toxic pigments and anti-corrosion coatings primarily consist of aluminum phosphate, zinc phosphate, and barium borate, among others. Of these, zinc phosphate and aluminum phosphate are the most effective and widely used.
III. Electrochemical Corrosion-Resistant Coatings
The main components of electrochemical corrosion-resistant coatings are metal powder pigments, adhesives, and additives.
Metal powder pigments, primarily composed of zinc powder (with a more negative electrochemical potential), occupy a significant proportion in the dry film. Therefore, electrochemical anti-corrosion coatings are also referred to as "zinc-rich anti-corrosion coatings." Zinc-rich anti-corrosion coatings utilize adhesives such as epoxy resins, epoxy plastics, polyurethanes, and chlorinated rubbers.
IV. Comprehensive Anti-Corrosion Coatings
Composite anti-corrosion coatings are formulated by combining two or more types of coatings based on the underlying mechanisms, such as conversion-stabilization, to compensate for the limitations of a single type.
Currently, widely used composite anti-corrosion coatings are based on low-molecular-weight epoxy resins and are two-component paints that can be formulated into high-solids and solvent-free paints. These paints have high cross-linking density and excellent corrosion resistance.