1.What is the basic definition and production process of SECC?
Core Features: SECC uses cold-rolled steel sheets (typically SPCC or SPCD) as a substrate, depositing a uniform pure zinc layer on the surface through an electroplating process. The zinc layer adheres tightly to the substrate, resulting in a smooth and even surface, making it suitable for applications requiring high aesthetics and precision.
Production Process: Cold-rolled substrate → Degreasing (removing oil stains) → Pickling (surface activation) → Electroplating (zinc ions are deposited on the substrate under the action of an electric field) → Passivation (forming a protective film) → Oiling (rust prevention) → Finishing (flattening and shearing).
The electroplating process allows for precise control of zinc layer thickness and can achieve varying zinc layer thicknesses on one or both sides (e.g., single-sided galvanizing for specialized corrosion protection requirements).
2.What are the zinc layer parameters and anti-corrosion performance?
Zinc coating weight: Common specifications are 10g/m², 20g/m², and 30g/m² (single-sided), with a total double-sided weight typically ranging from 20-60g/m², corresponding to a zinc coating thickness of approximately 1.4-8.5μm (zinc density is approximately 7.14g/cm³).
The zinc coating thickness uniformity is superior to that of hot-dip galvanizing (SGCC), with a tolerance within ±10%.
Corrosion protection: The zinc layer acts as a sacrificial anode to protect the substrate, while the passivation layer (such as chromate or chromium-free passivation) forms a dense film, further blocking corrosive media and providing superior fingerprint and corrosion resistance.
In indoor environments, SECC offers a rust protection period of 5-8 years, surpassing hot-dip galvanizing with the same zinc coating thickness.
3.What are the chemical composition and mechanical properties?
Base Material Composition: Consistent with cold-rolled base material. For example, the carbon content of SPCC-based SECC is ≤0.15% and the manganese content is ≤0.60%, ensuring excellent formability.
Mechanical Properties:
Tensile Strength: 270-370 MPa
Yield Strength: 130-250 MPa
Elongation: ≥25% (Electroplating has minimal impact on base material plasticity, superior to hot-dip galvanizing).
Performance: Strength similar to cold-rolled base material, with excellent plasticity, suitable for complex stamping and bending processes.
4.What is the surface condition and classification?
Surface Treatment:
Ordinary Electrogalvanized (SECC): The surface is a pure zinc layer, with optional passivation.
Fingerprint-Resistant Electrogalvanized (SECC-N): A fingerprint-resistant coating is applied after passivation to improve stain resistance and conductivity, making it suitable for electronic device casings.
Chromium-Free Passivation (SECC-E): Utilizes environmentally friendly passivating agents (such as silane and titanium), complies with RoHS and other environmental standards, and replaces traditional chromate passivation.
Surface Gloss: Available in glossy (highly reflective) and matte (lowly reflective). Glossy surfaces are suitable for decorative parts, while matte surfaces reduce glare (such as instrument panels).
5.What are the performance characteristics and application areas?
Core Advantages:
Excellent Surface Quality: Smooth and flat, with a uniform zinc layer and no hot-dip galvanizing defects, suitable for direct painting or exposed use.
Excellent Formability: The thin and ductile zinc layer withstands complex processes such as deep drawing and stretching without cracking or peeling.
Controllable Environmental Performance: A chromium-free passivation process allows compliance with environmental requirements, making it suitable for environmentally sensitive applications such as electronics and home appliances.
Typical Applications:
Electronics: Computer cases, mobile phone cases, printer frames (requiring precision forming and conductivity).
Home Appliances: Microwave oven linings, air conditioning panels, washing machine control panels (focusing on appearance and stain resistance).
Automotive: Interior components (such as instrument panel brackets and door trim panels), electronic component housings.
Precision Instruments: Medical device housings, instrument cases (requiring smooth surfaces and dimensional accuracy).