1.What is the most commonly used and cost-effective basic anti-corrosion solution?
Hot-Dip Galvanizing
Process: DC01 steel sheet is immersed in molten zinc, forming a zinc-iron alloy layer and a pure zinc layer.
Features: Excellent Corrosion Resistance: The zinc layer is relatively thick (typically 50-275 g/m² on both sides), providing excellent sacrificial anodic protection (zinc preferentially corrodes the iron substrate) and physical barrier protection. It is particularly resistant to atmospheric corrosion and performs well in industrial, rural, and mild marine environments.
Low Cost: Highly cost-effective and suitable for large-area applications.
Surface: The surface has zinc spangles (controllable size) and is relatively rough.
Weldability: Good, but zinc fume is produced during welding.
Grade Designation: DC01+Z (EN 10346)
Main Applications: Building structures (roofs, walls, purlins, ventilation ducts), distribution cabinets/enclosures, agricultural equipment, automotive structural/chassis components, general industrial frames, storage tanks, etc. Suitable for outdoor and harsh environments. Electrogalvanizing Process: A uniform layer of pure zinc is deposited on the surface of DC01 through electrolysis.
Features:
Excellent surface quality: The coating is thin (typically 5-50 g/m² on both sides), uniform, smooth, and spangle-free, resulting in an attractive appearance.
High dimensional accuracy: Minimal processing distortion.
Corrosion resistance: Good, but not as good as hot-dip galvanizing (thinner zinc layer) for the same weight. More suitable for indoor or high-quality environments. An ideal substrate for subsequent coatings (such as painting).
Formability: Excellent, particularly suitable for complex stamping.
Weldability: Excellent.
Grade designation: DC01+ZE (EN 10346)
Main applications: Automotive body panels (exterior/interior), appliance housings (refrigerator, washing machine, air conditioner panels), office furniture, computer cases, precision hardware, and components requiring a good appearance and subsequent painting.
2.What are the processes and characteristics of color-coated plates?
Process: Typically, one or more layers of organic coating (primer, topcoat, and backcoat) are continuously roll-coated over the zinc coating (DC01+Z or DC01+ZE), followed by a bake-curing process. Topcoats commonly used include polyester, silicone-modified polyester, polyurethane, PVC plastisol, and PVDF.
Features: Excellent corrosion and weather resistance: Combining the cathodic protection of the zinc coating with the physical insulation and weather resistance of the organic coating. PVDF coatings offer weather resistance of up to 20-30 years.
Decorative properties: Available in a variety of colors, gloss finishes (high gloss/matte), and textures.
Functionality: Optional coatings with special features such as self-cleaning, antibacterial, thermal insulation, and fire protection are available. Cost: Higher than a single coating.
3.What are the processes and characteristics of post-painting?
Process: After forming, DC01 parts (which can be bare, galvanized, or phosphated) are sprayed with either liquid paint or powder coating, which is then cured.
Features:
High Flexibility: Applicable to complex shapes and a wide selection of colors.
Diverse Performance: A wide variety of coatings (epoxy, polyester, acrylic, polyurethane, etc.) are available to meet diverse requirements for corrosion resistance, wear resistance, chemical resistance, and appearance.
Cost: Suitable for small batches or complex shapes; large quantities may be more expensive.
4.What are the processes and characteristics of phosphating?
Process: Immerse DC01 in a phosphate solution to form a microcrystalline phosphate conversion coating (zinc, iron, etc.).
Features:
Corrosion Protection: Limited, primarily providing short-term rust protection (for storage and transportation) and excellent paint/grease adsorption.
Main Application: As a pretreatment before painting (spray painting, powder coating) or oiling, significantly improving coating adhesion and corrosion resistance.
Friction Resistance: Phosphate coatings improve wear resistance and are often used for rust prevention during cold forming processes (such as wire drawing).
Applications: Almost standard pre-painting treatment. Also used for automotive components, fasteners, and other parts requiring subsequent processing or short-term rust protection.
5.What are the process and characteristics of passivation?
Process: Chemical treatment (usually using chromate or chromium-free passivation) is performed on the galvanized steel surface to form an extremely thin protective film.
Features:
Improves the corrosion resistance of the galvanized coating: Delays the formation of white rust (a corrosion product of zinc), providing rust protection during short-term transportation and storage.
Improves paint adhesion: An important pre-treatment step for pre-coating or post-coating.
Environmental protection: Chromium-free passivation is the mainstream trend.