Final Report - Strategic Environmental Research and Development ...

E vs. SCE (V)
E vs. SCE (V)
E vs. SCE (V)
(d)
Figure 3.1. (a) Speciation diagram for Ce species in 0.1M NaCl +300 ppm of Ce 3+ ion in
the absence of carbonates (OH - and Cl - anions). Speciation diagram for (b) Ce (c) Pr (d)
La species in the presence of carbonates from atmospheric CO 2 (OH - , Cl - and CO 3
2-
anions) in 0.1M NaCl +300 ppm of cation
-0.56
-0.56
-0.5
CeCl PrCl 3 3
LaCl 3
-0.64
0 ppm
-0.64
0 ppm
-0.6
0 ppm
-0.72
600 ppm
-0.72
600 ppm
-0.7
-0.80
-0.80
150 ppm
50 ppm
-0.8
300 ppm
-0.88
-0.88
300 ppm
-0.96
-0.96 300 ppm
-0.9
150 ppm 50 ppm
150 ppm
-1.04
-1.04
-1
600 ppm
-1.12
-1.12
-1.1
50 ppm
-1.20
10 -7 10 -6 10 -5 10 -4 -1.20
Log i (A/cm 2 10 -7 10 -6 10 -5 10 -4 -1.2
)
Log i (A/cm 2 10
)
-7 10 -6 10 -5 10 -4
Log i (A/cm 2 )
(a) (b) (c)
Figure 3.2. (a) Cathodic polarization curves of AA 2024-T3 in aerated 0.1M NaCl solution
with different concentrations of (a) CeCl 3 . (b) PrCl 3 (c) LaCl 3 .
5.3.1.3.3 Free corrosion exposure in lanthanide solutions. AA 2024-T3 coupons were
immersed at open circuit in 100 mM NaCl solution containing 300 ppm of the inhibitor chloride
at natural pH. Visual inspection shows inhibition by Ce 3+ and Pr 3+ was comparable while La 3+
showed least inhibition relative to the sample immersed in chloride-only solution. The sample
100