Tartric Sulfuric Anodizing (TSA)
N.B.: The information contained in this sheet comes from reliable sources. Nevertheless, it is provided without any guarantee, express or implied, of its accuracy.
Principle:
The sulfo-tartaric anodization is the result of an ALENIA patent improved by AIRBUS. Its objective is to replace Chromic Anodic Oxidation (CAO). It is generally implemented in a bath containing about 40 g/d of sulfuric acid and 80g/l of tartaric acid, at a temperature of 35 to 40°C. The constant voltage is 14/15V. The cycles of about 25 minutes include a voltage ramp of 5 minutes then a plateau of 20 to 25 minutes. The sulfo tartaric anodization forms very thin layers, 2 to 7 µm (thicknesses similar to those formed during an OAC). It generates a good corrosion resistance via the adhesion of the paint films, the painting being carried out on a non-clogged layer. Its influence on fatigue characteristics is moderate (about 20 to 30% reduction compared to the bare substrate, similar to that induced by an OAC.
SUBSTRATE:
All grades of alloys and for all processing methods. However, the alloy has a strong influence on the performance level obtained and the appearance.
VARIANTS:
In the case of unpainted parts requiring a high resistance to corrosion, the anodizing cycle is extended by about 15 minutes (TSA long cycle) to obtain thicknesses of 5 to 7 µm and a two-stage sealing is carried out, the first consisting of impregnation in a solution with a low level of trivalent Chromium followed by a hydrothermal sealing in water at 98°C.
APPLICATIONS :
Corrosion resistance.
Paint hanging base.
Unlike OAC, it cannot be used as a preparation before gluing. In this case, the Phosphoric Anodic Oxidation (PAO/PAA) recommended by BOEING or the Phospho Sulfuric Anodic Oxidation (PSA) recommended by AIRBUS should be chosen.
SECTORS CONCERNED : aeronautics / space (recommended by AIRBUS)
ENVIRONMENTAL IMPACT:
By removing the toxic and carcinogenic hexavalent chromium, this process is in accordance with the REACh regulation.
REFERENCE:
NF EN 4704 Aerospace series.
ISO 9227 Corrosion test in artificial atmospheres - Salt spray tests
EN ISO 2409 Paints and varnishes Grid test
Implementation
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