Improvement of the Corrosion Resistance of Aluminium Alloys Applying Diff erent Types of Silanes - Advanced Materials for Agriculture, Food and Environmental Safety - page 56

0,40

BTSE 5%, 2min
BTSE 5%, 5 min
BTSE 5%, 10 min

0,35

0,30

3

0,25

2

0,20

1

0,15

0,10

0,05

0,00

1800 1600 1400 1200 1000 800

Wavenumber (cm -1 )

Figure 2.18 FTIR spectra of bis-3-(triethoxysilyl) ethane i lm on TSA anodized AA 2024.
1 - BTSE 5%, 2 min conversion, drying at 100 ° C, 5 min; 2 - BTSE 5%, 5 min conversion,

drying at 100 ° C, 5 min; 3 - PSS 5%, 10 min conversion, drying at 100 ° C, 5 min.

to the layer density). In the case of conversion with BTSE and PSS 2%,
it can be noticed that the treatment time has nearly no inl uence on the
-Si-O-Si- peak intensity when compared with BTSE and PSS 5%, where
from the spectra the peak intensity has an increase proportional with the
conversion time.

2.6 Conclusions

It has been demonstrated that the silane mixture of bis-amino silane/bis-sul-
fur silane shows superior corrosion resistance properties when applied on
the aluminium surface compared to a mixture of bis-amino silane/VTAS
or only BTSE and bis-sulfur silane, respectively. A small volume of bis-
amino silanes is sui cient to generate hydrophilic properties on the sur-
face and to support the formation of a homogenous surface i lm on the
anodized AA 2024 sample. On the other hand, a large portion of bis-sulfur
silane enhances the hydrophobicity of the mixture i lm, being the basis for
good protective performance properties of the mixture when applied on
the AA2024 surface. h e mixture of bis-sulfur silane with bis-amino silane
in a ratio of 3:1 showed the highest corrosion resistance on AA 2024-T3.
h e improvement for this mixture is achieved by selectively overcoming
the major drawbacks of the two individual silanes. h e bis-sulfur/bis-amino
mixture enhances the corrosion resistance of aluminium alloys due to the