Core Principle

Both processes grow an aluminum oxide (Al₂O₃) layer on the surface, but different process conditions result in vastly different coating properties.

Type II (Cosmetic/Corrosion)

• Thickness: ~5-25 μm
• Purpose: Good corrosion resistance, allows dyeing in colors
• Applications: Electronic enclosures, panels, consumer products

Type III (Hardcoat/Wear Resistance)

• Thickness: ~25-75 μm
• Purpose: Extremely hard surface (approaching hardened steel)
• Color: Typically dark gray or black
• Applications: Pistons, high-wear robotic parts, valve bodies

Selection Guide:
• Type II: Primary goal is corrosion protection or appearance
• Type III: Part must resist sliding, friction, or abrasion