Table 3 Dynamic Electrochemical Impedance Parameters for API X120 steel in 3.5 wt% NaCl solution without and with Co2 purging in the absence and presence of various concentrations of PEI corrosion inhibitor.

From: Electrochemical and thermodynamic study on the corrosion performance of API X120 steel in 3.5% NaCl solution

T, °C

Cinh

µmol L−1

Rs,

Rpo,

Ypo × 10−6

snΩ −1 cm−2

n1

Rct,

Yct × 10−6

snΩ −1 cm−2

n2

θ

IE, %

20

Blank

12.8

62.02

154.4

0.904

345.1

119.27

0.880

—

—

25

12.2

107.4

153.1

0.906

1082

68.19

0.965

0.681

68.10

50

11.4

187.4

127.5

0.886

1398

63.19

0.968

0.753

75.31

75

13.6

274.4

126.6

0.918

1725

61.85

0.974

0.799

79.99

100

13.29

136.7

113.9

0.884

2416

49.6

0.865

0.857

85.71

30

Blank

14.17

66.82

286.5

0.985

308

296.4

0.857

—

—

25

14.2

19.63

231.1

0.735

822

254.1

0.849

0.625

62.53

50

13.5

31.6

223.3

0.839

1042

217.8

0.884

0.704

70.44

75

11.18

36.09

141.7

0.891

1245

166.6

0.974

0.752

75.26

100

12.6

40.6

123.6

0.813

1715

102.7

0.836

0.820

82.04

50

Blank

13.05

21.05

306.5

0.722

242.7

550.1

0.734

—

—

25

9.35

14.5

250.3

0.752

428

384.6

0.838

0.432

43.29

50

11.7

44.4

225.6

0.956

532

323.9

0.965

0.543

54.37

75

11.9

20.9

165.1

0.913

662

291.6

0.946

0.633

63.33

100

11.03

29.4

137.17

0.647

858

288.1

0.829

0.717

71.71

70

Blank

11.14

23.5

320.6

0.608

180

858.8

0.846

—

—

25

12.4

36.4

299.3

0.678

242.7

625.1

0.966

0.258

25.83

50

12.7

47.4

249.6

0.914

313.2

570.1

0.530

0.425

42.52

75

13.68

51.74

223.8

0.811

397.2

569.2

0.986

0.546

54.68

100

12.39

55.4

222.7

0.592

504.2

532.5

0.986

0.642

64.29

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