Cold-Rolled Anodized Aluminum Plate

Cold-Rolled Anodized Aluminum Plate

1. Material Definition & Process Flow

Cold-rolled anodized aluminum plate is a high-performance composite material produced by combining cold rolling technology (rolling below recrystallization temperature) with anodic oxidation treatment, integrating the mechanical properties of aluminum matrix with the protective characteristics of the oxide film.

2. Core Production Processes

（1）Cold Rolling Process

• Temperature Control: Rolling is conducted at temperatures below the recrystallization threshold (approximately 250–400°C) to avoid grain coarsening.

• Rolling Methods: Single-frame or multi-frame continuous rolling (e.g., three-roll system) with multiple passes (compressive reduction of 5–30%) to achieve target thickness (final sheet thickness: 0.1–3mm).

• Annealing Treatment: Post-rolling annealing at 150–200°C to eliminate residual stresses and restore plasticity.

（2）Anodic Oxidation Process

• Electrolyte: Sulfuric acid (density 1.8–2.0 g/cm³) or oxalic acid solution, with voltage 12–24V and temperature 15–20°C.

• Film Formation: Aluminum plate acts as the anode, undergoing oxidation to form a dense porous alumina film (3–10μm thickness).

• Post-Treatment:

• Cleaning: Removal of residual electrolytes.

• Sealing: Boiling water or organic solution closure of micro-pores to enhance corrosion resistance and weatherability.

3. Key Performance Indicators

• Coefficient of thermal expansion: 23.1×10⁻⁶/°C

• Density: 2.7 g/cm³

• Hardness: HV 500–1500 (oxide film hardness: gem level) |
  | Chemical Properties | - Corrosion resistance: Passes GB/T 9278 salt spray test (≥2000 hours)

• Acid/alkaline resistance: Stable in pH 2–12

• Self-cleaning: Low static charge, dust repellency |
  | Processing Performance | - Bending radius: ≥1.5t (t = sheet thickness)

• Stamping capability: Complex shapes formed in one step

• Weldability: Suitable for TIG/MIG welding |

4. Oxide Film Structure & Function

• Microstructure: Hexagonal honeycomb porous structure with 50–100nm pore diameter and 30–40% porosity.

• Functional Characteristics:

• Corrosion Resistance: Dense film prevents electrolyte penetration, with strong resistance to chloride ions.

• Weatherability: Outdoor use maintains color stability for >10 years (UV absorption rate >90%).

• Insulation: Volume resistance >1×10¹⁴ Ω·cm, suitable for electronic packaging.

5. Typical Application Fields

（1）High-End Construction

• Building Facades: Ultra-thin cold-rolled anodized aluminum sheets (0.8–1.2mm) used in modern exterior walls, offering lightweight (1/3 of glass weight) and high wind resistance (≥4kPa).

• Decorative Panels: Surface treatments (e.g., PVD coating) achieve metallic finishes (gold/silver) for luxury interiors.

（2）Precision Industrial Manufacturing

• Electronic Components: PCB substrates, chip carriers leveraging high insulation and thermal conductivity.

• Semiconductor Equipment: Chamber linings resistant to high-temperature plasma corrosion (≤800°C).

（3）Specialized Applications

• Aerospace: Satellite antenna reflectors, thermal insulation layers for extreme temperature environments (-270°C to +300°C).

• Medical Cleanrooms: Antimicrobial-coated surfaces (silver ion addition) meeting ISO 14644-1 Class 5洁净 standards.

6. Technical Development Trends

1. Nano-Oxide Films: Pulse electroplating to produce <50nm thin films for enhanced wear resistance and optical properties.

2. Functional Coatings: Development of conductive (ITO), self-healing, and other advanced coatings.

3. Green Processes: Low-temperature acid-free oxidation (e.g., plasma oxidation) to reduce energy consumption and environmental impact.

7. Comparative Advantages

Cold-rolled anodized aluminum plate, through material innovation and process optimization, has become a core material in high-end equipment, precision electronics, and sustainable construction, driving technological upgrades across multiple industries.