Electrochemical Measurements of Corrosion and Biofouling Films on Simulated OTEC Heat Exchangers
Electrochemical measurements of corrosion and biofouling films have been performed using a recently developed technique called Electrode Impedance Spectroscopy (EIS). EIS is based on the hypothesis that corrosion and biofouling films can be characterized by observing the steady-state response to a small amplitude sinusoidal perturbing potential imposed on the heat exchanger material.
Copper-nickel, aluminum, and titanium alloys were evaluated with specially designed EIS corrosion cells placed in flowing seawater. Results were compared with the weight loss of coupons in line with the corrosion cells.
The results from these tests indicated that instantaneous corrosion rates can be determined at low frequencies, changes resulting from biofouling occur at high frequencies, the occur- ance of localized corrosion and multiple fouling films can be identified, and the effect of cleaning the surface of the material can be readily determined.
KeywordsHeat Exchanger Corrosion Rate Bide Plot Flowing Seawater Ocean Thermal Energy Conversion
Unable to display preview. Download preview PDF.
- 1.Liebert, B.E.; Berger, L.R.; White, H.J.; Moore, J.; McCoy, Wm.; Berger, J.A.; and Larsen-Basse, J.: The Effects of Biofouling and Corrosion on Heat Transfer Measurements. Proc. Sixth OTEC Conf., Washington, D.C. (1979) 12. 7–12. 16.Google Scholar
- 2.Liebert, B.E.; Larsen-Basse, J.; Berger, J.; and Berger, L.R.: Biofouling and Corrosion Studies at Keahole Point, Hawaii (1978–1980). Proc. Eighth OTEC Conf., Washington, D.C. (1981) 421–430.Google Scholar
- 5.Sullivan, P.K.: Electrochemical Measurements of Corrosion and Biofouling Films on Simulated OTEC Heat Exchangers. Ph.D. Dissertation, Dept. Ocean Engineering, University of Hawaii (1985).Google Scholar
- 6.Mansfeld, F.: Recording and Analysis of AC Impedance Data for Corrosion Studies. I. Background and Methods of Analysis. Corrosion 36 (1981) 301.Google Scholar
- 7.Stern, M. and Geary, A.: A Method for Determining Corrosion Rates from Linear Polarization Data, Corrosion, 14 (1958) 440.Google Scholar
- 8.Godard, H.P.: An Insite Into the Corrosion Behavior of Aluminum, Materials Performance 20 (1981) 9.Google Scholar
- 10.Freeman, R.S.: Weight Loss, Potentiostatic Polarization, and Impedance Measurements of Three Aluminum Alloys. M.S. Thesis, Dept. Mechanical Engineering, University of Hawaii (1984).Google Scholar
- 11.Lewis, R.O. and F.L. LaQue: Evaluation of Copper-Nickel Alloys for OTEC Applications, Report by Argonne National Laboratory, Argonne, Illinois, ANL70TEC-BCM-019 (1981).Google Scholar