Surface finish impacts both thermal performance and durability.
- Thermal Performance: A bare aluminum surface has low emissivity in the infrared spectrum, limiting radiative heat transfer. Anodizing (especially black anodizing) significantly increases surface emissivity, enhancing radiative cooling, which can account for 10-25% of total heat dissipation in natural convection. However, the anodized layer is a thermal insulator; for conduction-based heat transfer (e.g., contact with a component), a bare, smoothly machined surface is superior.
- Durability: Anodizing creates a hard, non-conductive, and corrosion-resistant oxide layer, protecting the aluminum from oxidation and scratches. It also provides electrical insulation, which can prevent shorts. Other finishes like powder coating offer color and corrosion resistance but are thick thermal insulators and should not be used on critical thermal interfaces.