The synergistic effect of cavitation erosion and corrosion
The synergistic effect of cavitation erosion and corrosion
Experiments are described in which attempts have been made to investigate the fundamental mechanisms of the synergistic effect of cavitation erosion and corrosion. The design of an all-plastic cavitation tunnel is described which allows specimens to be held under potentiostatic control in a flowing seawater system. By taking both balance and current measurements it has been possible to divide the Mass Loss Rate (MLR) from copper and 70/30 Cu/Ni specimens, subjected to cavitation erosion and corrosion, into four separate components. It was hoped that these results would give a clear indication of the synergistic effect but difficulties were found in their interpretation therefore depth of penetration measurements were used. The synergistic effect was found to be most marked when cavitation erosion occurs in the presence of mild corrosion. For the worst case studied, where corrosion represented 9% of the total mass loss from the surface, 50% of the depth of penetration was caused by the synergistic mechanisms. Evidence is presented that this synergistic depth is an enhanced erosion mechanism. Whilst obtaining the MLR results an erosive mass loss was found to occur during the pure corrosion tests. Tests are described in which a critical velocity is determined, above which this erosive MLR term becomes significant. The current distribution over the specimen surface has been measured under differing hydrodynamic conditions using a multi-electrode specimen. Details of currents recorded within the main cavitation damage areas are given and are found to increase once mass loss occurs. A model of the corrosion current dependence on the fluid velocity is presented for both filmed and unfilmed surfaces mounted in the C.E.C. Tunnel. (D74048/87)
University of Southampton
1987
Wood, Robert J. K
(1987)
The synergistic effect of cavitation erosion and corrosion.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Experiments are described in which attempts have been made to investigate the fundamental mechanisms of the synergistic effect of cavitation erosion and corrosion. The design of an all-plastic cavitation tunnel is described which allows specimens to be held under potentiostatic control in a flowing seawater system. By taking both balance and current measurements it has been possible to divide the Mass Loss Rate (MLR) from copper and 70/30 Cu/Ni specimens, subjected to cavitation erosion and corrosion, into four separate components. It was hoped that these results would give a clear indication of the synergistic effect but difficulties were found in their interpretation therefore depth of penetration measurements were used. The synergistic effect was found to be most marked when cavitation erosion occurs in the presence of mild corrosion. For the worst case studied, where corrosion represented 9% of the total mass loss from the surface, 50% of the depth of penetration was caused by the synergistic mechanisms. Evidence is presented that this synergistic depth is an enhanced erosion mechanism. Whilst obtaining the MLR results an erosive mass loss was found to occur during the pure corrosion tests. Tests are described in which a critical velocity is determined, above which this erosive MLR term becomes significant. The current distribution over the specimen surface has been measured under differing hydrodynamic conditions using a multi-electrode specimen. Details of currents recorded within the main cavitation damage areas are given and are found to increase once mass loss occurs. A model of the corrosion current dependence on the fluid velocity is presented for both filmed and unfilmed surfaces mounted in the C.E.C. Tunnel. (D74048/87)
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Published date: 1987
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Local EPrints ID: 461119
URI: http://eprints.soton.ac.uk/id/eprint/461119
PURE UUID: 4bf4829b-6818-4028-8c45-49e1c072bbc1
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Date deposited: 04 Jul 2022 18:36
Last modified: 04 Jul 2022 18:36
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Author:
Robert J. K Wood
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