Erosion-corrosion of copper in cooling water systems at 60℃ using animpinging liquid jet and Electrochemical Quartz Crystal Microbalance

摘要

When water flows over copper, turbulence may be created at different parts of metal surfacern(such as bends, tees, sudden changes in section), and may be sufficient to cause breakdown ofrnthe surface layer, even with a solution that is free from suspended solids.rnAn impinging liquid jet directed at normal incidence onto a copper sample was used in thisrnwork. It was generated using a recirculating solution of 10-3M Na2SO4, continuouslyrndeaerated and heated at 60℃. Two types of copper samples were investigated: a bulk copperrnelectrode was first anodised to form a copper oxide layer, before submitting it to thernimpinging jet. The polarisation resistance was then measured as a function of the time ofrnimpinging. In an other test, an electrolytic copper layer was deposited on an EQCM, thenrnpolarisation resistance and mass change were followed as a function of the time of impinging.rnThe results are discussed from electrochemical and mass change measurements, and fromrnscanning electronic microscopic observations. Comparisons are made with the variation of thernpolarisation resistance measured as a function of time, in the same solution, using a rotatingrndisk electrode, at which no turbulence is assumed to occur.