Page 105 - Corrosion Engineering Principles and Practice
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80 C h a p t e r 4 C o r r o s i o n T h e r m o d y n a m i c s 81
2
1.5 Al 3+ AlO 2 –
b 10 –6 10 –4 10 –2 10 0
1 10 –2 0
10
Potential (V vs. SHE) –0.5 0 a 10 –6 Al 2 O ·H O
–4
0.5
10
3
2
–1
–1.5
AI
–2
–2 0 2 4 6 8 10 12 14 16
pH
FIGURE 4.13 E-pH diagram of aluminum with four concentrations of soluble
species (25°C).
2
1.5
b
1 3+
Potential (V vs. SHE) –0.5 a Al Al O ·H O AlO 2 –
0.5
0
2
2
3
-1 Cathodic protection range
–1.5
Al
–2
–2 0 2 4 6 8 10 12 14 16
pH
FIGURE 4.14 E-pH corrosion diagram of aluminum at 25°C with range where
cathodic protection is useful.
