1.How to pre-treat before zinc supplementation?
Rust removal
For rust and scale on the damaged part, use fine sand or wire brush to polish until the clean zinc layer or steel base is exposed.
If the rust is deep, use 10% dilute hydrochloric acid to etch lightly for 3-5 seconds, then rinse with clean water and wipe dry to prevent acid residue.
Degreasing and cleaning
Wipe the treated area with alcohol, acetone or special metal cleaner to remove oil stains and fingerprints (grease will cause the zinc layer to fall off) and ensure that the surface is non-sticky.
Drying: Use compressed air to dry or dry naturally to ensure that the surface is completely dry (moisture will affect the curing or adhesion of the zinc supplement material).
2.What is the universal zinc supplementation method for small area damage, outdoor/indoor?
Cold spray zinc: A zinc layer is formed by cold spray zinc coating with high zinc content, which forms electrochemical protection with the base zinc layer.
Operation process
After pretreatment, use a brush or spray gun to evenly apply the cold spray zinc coating to the damaged area, with a thickness of 30-50μm.
Cure at room temperature for 24 hours to form a zinc coating with good compatibility with the original galvanized layer.
Advantages: simple operation, strong adhesion, corrosion resistance close to hot-dip galvanizing, suitable for small area repairs.
3.What are the zinc supplementation methods suitable for industrial-grade repairs of medium to large-area damage?
Principle: Zinc wire/zinc powder is melted by electric arc or flame and sprayed onto the pre-treated surface at high speed to form a dense zinc layer.
Operation process
Sandblast the damaged area (reach Sa2.5 level, surface roughness 50-80μm) to enhance the adhesion of the zinc layer.
Use arc zinc spraying machine (high efficiency) or flame zinc spraying gun (flexible) to spray the molten zinc evenly. The distance (150-200mm) and speed of the spray gun need to be controlled to avoid zinc layer accumulation or missed spraying.
After spraying zinc, lightly sweep the surface with a wire wheel to remove floating zinc, and spray a second time if necessary.
Advantages: The zinc layer thickness is controllable and has excellent anti-corrosion performance. It is suitable for zinc supplementation after component welding and large-area rust repair (such as bridge components).
4.Which zinc supplementation method is suitable for small-area repairs of precision components?
Principle: Electrolysis is used to deposit a zinc layer on the damaged area, and the thickness can be precisely controlled
Operation process
Finely grind and degrease the damaged area, and use insulating materials to cover the non-repaired area.
Use acidic zinc plating electrolyte, use the component as the cathode and the zinc plate as the anode, control the current density and time to ensure uniform deposition of the zinc layer.
After electroplating, rinse with clean water to remove residual electrolyte, and perform passivation treatment if necessary.
Advantages: The zinc layer is uniform and the surface is smooth, which is suitable for repairing precision components (such as instrument housings and small connectors).
5.For temporary corrosion protection and emergency treatment, how should we choose the zinc supplementation method?
Zinc block/zinc sheet riveting: Using the sacrificial anode principle, the zinc block is fixed near the damaged area with rivets. The zinc block preferentially corrodes and protects the steel.
Operation process: Drill holes around the damaged area and fix the zinc block (size is determined by the damaged area, usually 50×50×5mm) with stainless steel rivets to ensure that the zinc block is in close contact with the steel.
Suitable for scenes where coating repair cannot be performed immediately (such as outdoor pipelines and large steel structures) as a temporary anti-corrosion measure.
Advantages: Fast operation, no need for complex equipment, suitable for emergency treatment.