=== Cracking ===

Due to the difference of thermal expansion coefficient between the anodic film and the substrate, heating induces tensile stresses in the coating that can lead to cracking if the fracture limit is reached.

=== Flaking ===

The major risk for space applications is not simply the cracking of the surface layer but flaking, because the particles released could settle on cold parts, typically mirrors, lenses or mechanisms.Then the satellite instruments would be damaged decreasing the mission’s lifetime. In addition, a high level of flaking could change the thermo-optical properties of the surface affecting thermal control.

Flaking is generally observed on parts that had been thermally cycled. The loss of adhesion is revealed for example on pulling off tapes used to fix thermocouples to the surface during thermal cycles.

=== Crazing ===

Anodized finishes will craze (crack) when the aluminum substrate is deformed in any fashion. This happens because the base aluminum has a marginal degree of elasticity, while the anodized coating has virtually no elasticity. When the part is bent, the aluminum will deflect quite far without failing, but the coating cracks immediately upon deflection.

== Testing ==