Cold Galvanizing Compound Spraying Process
Release time：
Mar 28,2025
Use solvents or alkaline cleaning agents to remove oil and lipid pollutants, and mechanically grind or pickle to remove rust.
Cold Galvanizing Compound Spraying Process Construction Process
I. Substrate Surface Treatment (Key Steps)
1. Degreasing and rust removal
Use solvents or alkaline cleaning agents to remove oil and lipid pollutants, and mechanically grind or pickle to remove rust .
Welds and sharp angles need to be polished to R2, and the cut marks and hardened layers of the gas-cut surface need to be removed .
2. Sandblasting
Sandblasting /shot blasting reaches Sa2.5 level (ISO 8501), and the roughness is controlled at 25-80μm .
It is recommended to use abrasives such as quartz sand and steel shots, and use compressed air to remove residual impurities after treatment .
3. Drying and cleaning
The surface humidity of the substrate needs to be ≤85%, and the temperature is at least 3°C higher than the dew point to ensure that there is no water or oil .
II. Coating Preparation and Construction
1. Coating preparation
The single component needs to be stirred evenly, and the two components are mixed in proportion (such as 4:1), mechanically stirred for 5-10 minutes, and left to mature for 15-30 minutes .
If necessary, add special diluent to adjust the viscosity to avoid bubbles.
2. Construction method
Airless spray: high-pressure equipment (15- 20MPa), nozzle 0.43-0.53mm, spray width 25cm, uniform gun movement.
Air spray: aperture 2.5mm, gun distance 25cm, spray width 15cm, cross-cross method spray 2 times.
Brush /roller coating: used for small area repair, one-way coating is required to avoid missing coating.
3. Coating control
Wet film thickness 80-120μm, dry film 60-100μm (single pass), total thickness does not exceed 1.5 times the design value.
When using layered construction, the interval time is 1-6 hours (adjusted according to coating thickness and ambient temperature).
III. Curing and Quality Inspection
1. Curing conditions
Natural curing: 24 hours at 25℃ to reach solid dryness, 7 days to fully cure.
Heating and curing: Baking at 60℃ for 1 hour can accelerate the reaction (depending on the product instructions).
2. Quality inspection
Film thickness inspection: The magnetic thickness gauge allows an error of ±10%, and the weld and other parts are controlled at 0.8-1.5 times the design value.
Adhesion test: Cross-cut method (0-1 level qualified) or pull-off method (≥5MPa).
3. Appearance inspection: No sagging, pinholes, or missing coating, and uniform color.
IV. Precautions
1. Environmental control : Construction temperature 5-35℃, humidity ≤85%, avoid rainy days or high humidity environments.
2. Zinc salt treatment : If white rust appears on the surface of the coating, it needs to be removed before applying the next coat of paint .
3. Layered construction : The interval between cold-sprayed zinc and intermediate paint and topcoat must meet the specifications to avoid coating failure.
V. Post-maintenance: Check the integrity of the coating regularly, and local damage needs to be polished and repainted.
Avoid mechanical impact or prolonged exposure to humid environments.
Through the above process, the cold zinc spraying process can achieve the long-term anti-corrosion effect, with both cathodic protection and barrier protection.
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