Galvanizing process

In many scenarios in industrial production, construction and daily life, galvanized plates are widely used for their good corrosion resistance. However, when galvanized sheets are in humid environments, their corrosion resistance face severe challenges. The abundant moisture and oxygen in humid environments create favorable conditions for metal corrosion. If appropriate protective measures are not taken, galvanized plates may have rust, damage and other problems, which will affect its service life and use effect. Therefore, the protection of galvanized plates in humid environments is particularly important.

Surface pretreatment strengthening.

Cleaning treatment: It is crucial to thoroughly clean the surface before further protection of the galvanized sheet. In humid environments, dust, oil, impurities, etc. are easily adhered to the surface of the galvanized plate. These substances will hinder the close integration of the protective coating and the galvanized plate, and may also become the inducing point of corrosion. Professional detergents, such as neutral degreasers, combined with soft cloth or brushes, can be used to carefully wipe the surface of the galvanized plate to remove all kinds of contaminants. For oil stains that are difficult to clean, organic solvents can be used for cleaning, but be careful to avoid damage to the galvanized layer. After the cleaning is completed, rinse it with clean water and ensure that the surface is completely dry, laying a good foundation for subsequent protective treatment.

Passivation treatment: Passivation is an effective pretreatment method to improve the corrosion resistance of galvanized plates in humid environments. By forming a passivation film on the surface of the galvanized plate, air and moisture can be further isolated and the occurrence of corrosion reactions can be suppressed. Common passivation treatments include chromate passivation and chromium-free passivation. Chromate passivation can form a relatively dense passivation film with excellent protection performance. However, due to the toxicity of hexavalent chromium, it has potential harm to the environment and human health, chromium-free passivation technology has been widely used and developed in recent years. The chromium-free passivating agent mainly includes titanium salt, zirconium salt, etc., and the passivating film formed also has good corrosion resistance and better environmental protection performance. When performing passivation treatment, the passivation fluid concentration, treatment time and temperature must be strictly controlled according to the process requirements.

parameters to ensure the quality of the passivation film.

Coating protection applications

Organic coating: Organic coating is a common method to protect galvanized plates in humid environments. All kinds of organic coatings such as paints and coatings can form a physical barrier on the surface of the galvanized plate to prevent corrosive media such as moisture and oxygen from contacting directly with the galvanized plate. For example, epoxy paint has good adhesion, chemical corrosion resistance and wear resistance, and can effectively resist erosion in humid environments. Before applying epoxy paint, the surface of the galvanized plate needs to be roughened appropriately to enhance the adhesion of the coating. At the same time, it is necessary to ensure that the coating thickness is uniform. Generally, the coating thickness is controlled between 50-200 microns depending on the harshness of the use environment. In addition, acrylic paint, polyurethane paint, etc. are also commonly used for the protection of galvanized plates. They each have their own characteristics and can be selected according to actual needs.

Thermal spray coating: Thermal spraying technology is to heat coating materials such as metal or ceramics to a molten or semi-melting state, atomize them through high-speed airflow and spray them onto the surface of the galvanized plate to form a solid coating. Thermal spray coating has high hardness, wear resistance and corrosion resistance, and can provide reliable protection for galvanized plates in humid environments. For example, zinc-aluminum coatings combine the excellent properties of zinc and aluminum and have resistance to atmospheric corrosion. The thickness of the thermal spray coating can be adjusted as needed, generally between 0.1-1 mm. However, thermal spraying equipment is costly, the construction process requirements are strict, and professional personnel are required to operate it.

Environmental control measures

Humidity adjustment: In an indoor environment where galvanized plates are used, controlling air humidity is an important measure to reduce the risk of corrosion. Dehumidification equipment, such as dehumidifiers, can be used to keep the ambient humidity within the appropriate range. Generally speaking, the relative humidity is controlled below 60%, which can effectively reduce the possibility of water film forming on the surface of the galvanized plate and inhibit corrosion reaction. For large warehouses or industrial plants, dehumidification systems can be installed to achieve accurate control of the humidity of the entire space.

Ventilation management: Good ventilation can take away water vapor and corrosive gases in humid environments in a timely manner to prevent them from agglomerating on the surface of the galvanized plate. When designing and building a place for storing galvanized plates, a ventilation system should be planned reasonably to ensure that the air can circulate fully. For example, install a number of vents and install exhaust fans and other equipment to promote air circulation. At the same time, pay attention to the position and direction of the vents to avoid introducing air containing a large amount of dust, impurities or corrosive substances.