The whole process of rust prevention of galvanized steel plates: from basic protection to long-term maintenance

Galvanized steel sheet is a widely used metal material in modern industry. Its anti-rust treatment process is directly related to the service life and safety performance of the product. This article will introduce the whole process of anti-rust treatment of galvanized steel sheet in detail, including key links such as pretreatment, galvanizing process, post-treatment and daily maintenance, and provide professional reference for related industries.

1. Surface pretreatment of galvanized steel sheet before anti-rust treatment
The anti-rust effect of galvanized steel sheet depends largely on the quality of the surface treatment in the early stage. The work at this stage lays a solid foundation for the subsequent coating adhesion.

Degreasing and cleaning process

Use alkaline degreasing agent to remove oil stains on the surface of steel plate, and control the temperature at 60-80℃

Ultrasonic cleaning technology can improve the cleaning effect of complex components

Continuous water film testing verifies the cleaning effect to ensure that there is no oil residue on the surface

Acid pickling and rust removal process

Use 10-15% hydrochloric acid solution, and keep the temperature at room temperature to 40℃

The pickling time is adjusted according to the degree of rust, usually 10-30 minutes

Add corrosion inhibitor to reduce the loss of base metal, and the Fe²⁺ concentration of acid solution is controlled below 120g/L

Surface activation treatment

Activate with dilute hydrochloric acid or ammonium bifluoride solution to remove the surface oxide film

Maintain the surface micro-roughness and enhance the adhesion of the zinc layer

After treatment, it needs to be fully washed with water to prevent residual acid from affecting the quality of the coating

II. Detailed explanation of the core links of the galvanizing process

The galvanizing process is the core stage of rust prevention treatment, and different galvanizing methods are suitable for different application scenarios

Hot-dip galvanizing process

The temperature of zinc liquid is controlled in the range of 445-465℃

The zinc dipping time is adjusted according to the thickness of the steel plate, usually 3-8 minutes

Adding alloy elements such as aluminum and nickel to improve the coating performance

Using air knife control technology to accurately adjust the coating thickness

Electrogalvanizing process

Using sulfate or chloride electrolyte system

Current density 10-50A/dm², affecting the deposition speed of the coating

Pulse electroplating technology can improve the uniformity and density of the coating

Trivalent chromium passivation treatment enhances corrosion resistance

Mechanical galvanizing process

Suitable for batch processing of small parts, energy-saving and environmentally friendly operation at room temperature

Coating thickness 10-50μm, uniform and free of hydrogen embrittlement

Using glass beads as impact medium to promote cold welding of zinc powder

III. Key technologies for post-galvanizing treatment

Post-treatment technology can further improve the rust resistance and service life of galvanized steel sheets.

Passivation treatment technology

Chromate passivation: Forming Cr₂O₃ protective film to enhance corrosion resistance

Chromium-free passivation: environmentally friendly molybdate and silicate systems

Color passivation, blue-white passivation, etc. meet different appearance requirements

Sealing treatment process

Silicone resin sealant fills the micropores of the coating

Nano-SiO₂ composite coating improves surface hardness

High-temperature curing forms a dense protective film

Coating matching system

Classic matching solution of epoxy primer + polyurethane topcoat

Synergistic anti-corrosion effect of zinc-based coating and galvanized layer

Powder spraying technology realizes solvent-free environmentally friendly coating

IV. Daily maintenance and repair of galvanized steel plates
Scientific maintenance can maximize the service life of galvanized steel plates.

Regular inspection and evaluation

Visual inspection: development of white rust and red rust

Coating thickness gauge monitors the progress of zinc layer loss

Cross-cut test evaluates coating adhesion

Cleaning and maintenance specifications

Neutral detergent with soft cloth for wiping

High-pressure water gun cleaning pressure does not exceed 150 bar

Avoid using detergents containing chloride ions

Local repair technology

Zinc-based touch-up paint repairs small area damage

Thermal spray zinc technology repairs important structural parts

The repair area needs to be passivated again

V. Development trend of rust prevention technology for galvanized steel plates
Rust prevention technology continues to innovate to meet higher environmental protection and performance requirements

Environmentally friendly surface treatment

Chromium-free passivation technology performance is close to traditional processes

Breakthrough in the research and development of bio-based conversion films

Low-temperature curing coatings reduce energy consumption

Intelligent monitoring system

Real-time monitoring of IoT corrosion sensors

Big data analysis predicts remaining service life

Automatic inspection of large-area galvanized structures by drones

Composite protection system

Progress in the research and development of graphene-modified zinc coatings

Successful laboratory stage of self-repairing coating technology

Exploratory research on optoelectronic synergistic anti-corrosion technology

Through the above full-process anti-rust treatment, galvanized steel sheets can maintain excellent corrosion resistance in various harsh environments. Enterprises should choose the most suitable anti-rust treatment solution based on product use, environmental conditions and cost budget, and establish a complete maintenance system to ensure that galvanized steel sheets can achieve maximum protection effectiveness.