Final Report - Strategic Environmental Research and Development ...

C [F/cm 2 ]
Rcorr [ohm*cm 2 ]
Rcorr
1.0E+08
Alodine Boegel Metallast PreKote TCP
1.0E+07
1.0E+06
1.0E+05
1.0E+04
1 10 100 1000
Time [hrs]
Figure 6.8. R corr response for samples treated with Sicopoxy primer and 5 different
conversion coatings: Alodine, Boegel, Metallast, PreKote and TCP (EIS test area
A=13.2 cm 2 ).
The metal-coating capacitance response C dl for all samples tested, grouped by primer, can be
seen in Figures 6.9-6.11. The time needed for the C dl to show a noticeable increase is compiled
in Table 6.2 together with the delaminated area parameter A del . As expected from the higher
sensitivity of the EIS technique compared to the visual examination with the un-aided eye, the
time needed for C dl to increase was always less than or equal to TTF. Samples treated with
Metallast pre-treatment and Sicopoxy or Hentzen primers deviated from the expected behavior,
i.e. showed visual signs of corrosion sooner than a change in the capacitance response. Future
research is needed to assess the reason of this Cmetal deviation.
1.E-02
1.E-03
Metallast Alodine Boegel PreKote TCP
1.E-04
1.E-05
1.E-06
1.E-07
1.E-08
1.E-09
1 10 100 1000
Time [hrs]
Figure 6.9. Metal-Coating capacitance response (C dl ) for samples treated with Deft
primer and 5 different conversion coatings: Metallast, Alodine, Boegel, PreKote and TCP
(EIS test area A=13.2 cm 2 ).
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