1.How do surface coatings/platings improve corrosion resistance?
By applying organic materials such as polymer resins and coatings, a protective layer with a thickness of 10-50μm is formed, balancing corrosion resistance and appearance. It is suitable for applications such as home appliances and light industrial products.
Common Types:
Spray Painting/Plastic Spraying: Examples include amino paint for home appliance exteriors and powder coating for automotive interiors (heat-resistant, abrasion-resistant, and moisture-insulating);
Functional Resin Coating: Examples include food-grade epoxy coating for refrigerator interiors (resistant to condensation and food juices, meeting food safety standards);
Laminating: Examples include DC06 surface-laminated PET and PVC films (used for furniture panels and decorative parts, offering both corrosion resistance and decorative properties).
Advantages: Low cost, wide range of color/appearance options, and adjustable coating thickness (thicker coatings offer greater corrosion resistance);
Applicable Applications: Indoor appliances, furniture parts, electronic device housings, and other non-extremely corrosive environments.
2.Can Metal Coatings Improve Corrosion Resistance?
DC06 is coated with a metal layer through processes such as electroplating and hot-dip galvanizing, leveraging the metal's inherent corrosion resistance (or "sacrificial anode protection") to enhance overall corrosion resistance. Galvanizing is the most commonly used coating for DC06.
Common Types:
Electrogalvanizing: Coating thickness 5-15μm. The surface can be further passivated (such as chromate passivation). Neutral salt spray resistance can reach 240-480 hours (no noticeable rust), making it suitable for automotive interior functional parts and hardware accessories.
Hot-dip galvanizing: Coating thickness 20-50μm (thicker than electrogalvanizing) offers enhanced corrosion resistance (up to 720 hours in salt spray testing). However, thicker coatings may affect the deep-draw formability of DC06 and are only suitable for simple parts that are hot-dip coated after forming (such as brackets).
Chromium/nickel plating: Thin coatings (2-5μm) with a bright surface. They are primarily used for high-precision, decorative parts (such as instrument panels and small hardware). Corrosion resistance is superior to zinc plating, but the cost is higher.
Core Principle: The zinc coating protects the substrate through the "sacrificial anode effect"-even if the coating is partially damaged, the zinc corrodes before the iron, preventing rust on the steel substrate.
3.Does passivation/phosphating improve corrosion resistance?
A chemical reaction forms an extremely thin (0.1-1μm) oxide or phosphate film on the surface of DC06. While this film cannot alone provide long-term corrosion resistance, it can serve as a supplementary protective measure.
Passivation Treatment:
Common Types: Chromate Passivation (traditional solution with strong corrosion resistance) and Chromium-Free Passivation (environmentally friendly solution, such as Zirconate Passivation).
Purpose: Used for short-term storage of bare DC06 parts (e.g., pre-shipment passivation can extend the rust-proof storage period to over 6 months), or as a post-treatment for zinc/chrome plating (to enhance the corrosion resistance of the coating).
Phosphating Treatment:
Purpose: Forms a porous phosphate film on the surface. It is primarily used as a pre-treatment for organic coatings-strengthening the adhesion between the coating and the substrate and preventing coating detachment (e.g., phosphating before painting appliance housings can improve the coating's weather resistance).
Applicable Applications: Short-term storage of bare parts and pre-treatment of coatings/platings.
4.How to reduce corrosion risk from the source?
Avoid Water/Contamination Accumulation Structures
Design Requirements: Avoid low-lying areas or grooves on the part surface, or provide drainage holes in low-lying areas (for example, DC06 parts for air conditioning ducts require condensation drainage holes).
Principle: Prevent corrosive media such as water, dust, and salt from remaining on the surface for a long time, reducing "localized water accumulation corrosion" (such as spot rust).
Reduce Crevice Structures
Design Requirements: When splicing DC06 with other materials (such as plastics and rubber), avoid narrow gaps (less than 0.1mm wide) or fill gaps with sealant (such as silicone sealant).
Principle: Narrow gaps are prone to "crevice corrosion" (where oxygen deprivation within the gap creates localized electrochemical corrosion cells, accelerating rust). Sealant can prevent media from entering the gap.
Optimize Surface Morphology
Requirement: Keep the surface of DC06 parts as smooth as possible (reduce roughness, such as reducing the Ra to ≤0.8μm through fine grinding or polishing).
Principle: Rough surfaces are prone to dust and moisture accumulation, increasing the contact area between corrosive media and the surface. Smooth surfaces reduce adhesion and facilitate cleaning.
5.How to control the use environment to adapt to the corrosion resistance limitations of DC06?
Control humidity and temperature.
Storage/usage environment: Humidity ≤ 60%, stable temperature (avoid condensation caused by frequent hot and cold cycles).
Measures: Dehumidifiers can be used indoors (such as warehouses in the rainy season in southern China). Temporary outdoor storage should be covered with waterproof cloth to prevent direct contact with rainwater.
Isolate from corrosive media.
Avoid exposure: Do not use unprotected DC06 parts in "high-salt environments" (such as outdoor areas in coastal areas), "industrially polluted environments" (such as near chemical plants), or "long-term contact with liquids" (such as uncoated sink parts).
Cleaning and maintenance: Regularly clean the surface of DC06 parts (such as wiping the interior of household appliances to remove condensation and food residue) to prevent long-term adhesion of media. Short-term Protection Aids
Temporary Storage: Unprocessed DC06 cold-rolled coils/sheets can be wrapped in anti-rust paper and protected with desiccant to extend their storage life to 3-6 months.
Post-Processing Protection: After processing DC06 parts, if they are not yet assembled, they can be sprayed with a short-term anti-rust oil (such as a thin layer). This can be removed with a solvent before subsequent assembly.