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ME442 -Corrosion Engineering
Genral Information about ME442
Page created in July 1995 last updated December 2000. Send your comment to Dr Qiu at [email protected]
ME442 -Corrosion Engineering is a 4 AU subject with 39 hours lectures and 12 hours tutorials. It is tought by Dr Qiu Jianhai and Dr Tan Yong Jun . The following prescribed textbook is available from the University Bookshop:
Principles and Prevention of Corrosion
by Denny A. Jones, 2nd edition, Prentice-Hall
1996 [Back to Top]
1. A carbon steel test specimen of dimensions 2 in. x 3 in. x 0.125 in. with a 0.25 in. hole for suspending in solution is exposed for 120 hours in an acid solution and loses 150 mg. Calculate the corrosion rate in mpy and mm/y.
2. What experimental precautions must be taken to ensure maximum accuracy in the measured weight loss of Question No.1?
3. Three more identical test specimens are included with the one from Question No.1 in a planned interval testing program. One is exposed for 12 hours and loses 25 mg. A second is exposed for 108 hours and loses 130 mg. The third is inserted in the solution when the second is removed and shows a weight loss of 15 mg after removal with the specimen of Question No.1. what is the effect of time on the solution corrosiveness and the specimen corrodability?
4. Plot the following cathodic polarization data for carbon steel in 0.5 N H2SO4 on linear coordinates and determine the polarization resistance. From the shape of the plot would you estimate that the absolut evalue of ßa is greater than or less than ßc?
| Current density (µA/cm2) | 40 | 100 | 160 | 240 | 300 |
| Cathodic polarization (mV) | 1.0 | 2.5 | 4.1 | 6.3 | 9.0 |
5. With the following anodic and cathodic polarization data, same conditions as Question 4 but greater currents, plot the polarization curves on semilogarithmic coordinates and determine ßa, ßc, Ecorr, and iCorr.
| Current density, A/cm2 (Anodic or Cathodic) |
Potential, Anode, V(SCE) | Potenital,Cathode, V(SCE) |
| 1.01x10-4 | -0.510 | -0.520 |
| 2 | -0.508 | -0.522 |
| 3 | -0.503 | -0.530 |
| 5 | -0.499 | -0.540 |
| 7 | -0.494 | -0.549 |
| 1x10-3 | -0.490 | -0.562 |
| 2 | -0.477 | -0.585 |
| 3 | -0.470 | -0.602 |
| 5 | -0.458 | -0.627 |
| 7 | -0.448 | -0.644 |
| 1x10-2 | -0.437 | -0.660 |
| 2 | -0.420 | -0.688 |
6. From the results of Question No.5, calculate the value of the proportionality
(Stern-Geary) constant, B and then determine iCorr using Rp found in Question
No.4.
7. Lab session: LPR technique to determine the corrosion rate of steel in 3.5% NaCl
solution.
8. Lab session: Tafel extrapolation to determine the corrosion rate of steel in 3.5% NaCl solution. Compare the results from LPR and Tafel.
9. Lab session: Cyclic polarisation of Type 316 stainless steel in H2SO4.
10. Lab session: Electrochemical Impedance Spectroscopy to determine corrosion rate of steel in 3.5% NaCl solution.
11. Rust never sleeps! Wanted to see Corrosion in Action ? Join the Guided Tour of Yunnan
Garden...... To identify the Good, the Bad and the Ugly.
12. Sketch the cyclic polarization curve for Type
304 stainless steel, showing exact values of the pitting and protection potentials.
Compare this sketch with the trace of potential vs. Time in the following figure for type
304 stainless steel and indicate the significance of pitting and protection potentials on
the potential-time plot in Fig 7.11 (page 211).
13. Calculate the degree of sensitization for a type 304 stainless steel which shows the
following results from the EPR test:
reactivation charge=1.71 coul, ASTM grain size=5, surface area=2.12 cm2. Is this
material sensitized according to the sensitization guidelines ?
