Tartaric Sulphuric Acid (TSA) anodising is primarily for corrosion protection. Airbus recommend this process (or Phosphoric Anodising) to replace chromic acid anodising. Tartaric acid is added to sulphuric acid anodising baths to generate porous anodic film that provides corrosion resistance to practical aerospace alloys and reduces the environmental impact of the traditional chromic acid anodising process.
The main managed properties are corrosion resistance, paint adhesion, fatigue, and quality of the coating. The key technical requirement for the anodising processes of aluminium is a balance between three criteria:
- The adhesion with a homogeneous porosity,
- The corrosion resistance depending on the porosity,
- The fatigue properties.
With this process, care must be taken regarding fungal contamination: The TSA/PSA electrolytes are less toxic than CAA and fungus growth in the treatment line can be an issue. The installation of preventive measures (e.g. filters, UV-lamps) is recommended.