Corrosion in Organic Acids
The corrosiveness of organic acids is not strong. Corrosion test data in formic acid, acetic acid, and propionic acid show that Ni200, Monel400, and nickel-base and iron-nickel-based corrosion-resistant alloys containing Cr, Mo all show excellent results in boiling solutions. Corrosion resistance, in contrast, corrosion resistance of nickel-base and iron-nickel-based corrosion-resistant alloys added in combination with Mo and Cr is the best. Doping organic acids with oxidants will increase the corrosion of non-Cr alloys. Some corrosion test data are summarized in the following table.
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Corrosion of corrosion resistant alloys in organic acids |
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|
Grade |
corrosion average rate/ mm﹒a⁻¹ |
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|
10% acetic acid |
99% acetic acid |
40% formic acid |
88% formic acid |
|
|
alloy 200 |
/ |
0.11 |
0.26-0.27 |
0.31-0.34 |
|
alloy 400 |
/ |
0.015 |
0.038-0.068 |
0.024-0.028 |
|
alloy 825 |
0.015-0.016 |
/ |
0.2 |
0.064-0.08 |
|
alloy 600 |
/ |
/ |
0.25 |
/ |
|
G |
0.011-0.014 |
0.03 |
0.013 |
0.099-0.12 |
|
G-2 |
/ |
0.005 |
/ |
0.05-0.067 |
|
G-3 |
/ |
0.015 |
0.046-0.05 |
0.14-0.15 |
|
alloy 625 |
0.01-0.019 |
0.01 |
0.17-0.19 |
0.236-0.238 |
|
alloy C-4 |
/ |
0.0005 |
0.07-0.076 |
0.05-0.076 |
|
hastelloy C-276 |
0.011-0.0114 |
0.0076 |
0.07-0.074 |
0.043-0.048 |
|
alloy C-22 |
/ |
/ |
/ |
0.023 |
|
alloy B-2 |
0.011-0.013 |
0.03 |
0.008-0.01 |
0.00025-0.0041 |
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Effect of Oxidizing Ions on Corrosion Resistance of Ni200 and Monel400 in Boiling Acetic Acid |
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|
Grade |
acetic acid concentration % |
corrosion average rate/ mm﹒a⁻¹ |
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|
no air |
blowing air |
3800×10⁻⁶Cu²⁺① |
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|
alloy 200 |
100 |
0.036 |
0.025 |
0.81 |
|
alloy 400 |
100 |
0.0025 |
0.05 |
2.97 |
|
alloy 200 |
50 |
0.076 |
1.6 |
0.71 |
|
alloy 400 |
50 |
0.025 |
2.1 |
0.9 |
|
Corrosion of some alloys in propionic acid |
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|
Grade |
propionic acid concentration % |
corrosion average rate/ mm﹒a⁻¹ |
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|
50ºC |
75ºC |
Boiling |
||
|
monel400 |
50 |
0.28 |
0.13 |
0.076 |
|
80 |
0.4 |
0.15 |
0.25 |
|
|
99 |
0.48 |
1.19 |
0.53 |
|
|
B |
50 |
0.38 |
0.1 |
0.05 |
|
80 |
0.61 |
0.3 |
0.13 |
|
|
99 |
0.15 |
0.64 |
0.28 |
|
|
C |
50 |
|
|
0.025 |
|
80 |
|
|
0.025 |
|
|
99 |
|
|
0.025 |
|
Post time: Apr-16-2018