Anodizing Metallurgy: Qualanod Standards, Layer Thickness (15-20µm) & Salt Fog Life
How electrolytic anodizing creates an integrated sapphire-hard aluminum oxide layer resistant to UV, salt mist, and acidic atmospheric pollutants.
Key Engineering Takeaways
- ✓ Qualanod certified process guarantees layer thickness and complete pore sealing
- ✓ Class 15 (15µm) provides 25+ year life in normal outdoor atmospheres
- ✓ Class 20 (20µm) provides marine-grade protection tested to 1,000+ hours acetic salt spray
Electrochemical Anodizing & Sealing Process
Unlike applied paints, anodizing is an electrochemical conversion process where aluminum acts as the anode in a dilute sulfuric acid electrolyte. An electrical current converts the surface into porous aluminum oxide (Al2O3). The extrusion then passes to high-temperature nickel-acetate sealing baths at 98°C, hydrating and closing the microscopic pores to seal out moisture.
Layer Thickness Classes (Class 15 vs Class 20)
Standard industrial solar racking requires Class 15 (nominal 15 microns, minimum 12 microns). In severe marine coastal areas (within 5 km of sea) or high-chemical industrial parks, SolarAlu recommends Class 20 (nominal 20 microns) for superior pitting resistance.
Frequently Asked Technical Questions
What is the difference between mill finish (raw) and anodized?
Can solar rails be powder-coated in black?
Require Project Statics Calculation?
Our engineering desk calculates project-specific wind uplift and snow load moment capacities according to Eurocode 9 within 24 hours.