Erosion-Corrosion Behavior of 90/10 and 70/30 Copper-Nickel Tubes in 1 wt% NaCl Solution

The erosion-corrosion behavior of 90/10 and 70/30 copper-nickel tubes was investigated by in situ electrochemical tests on a self-built loop apparatus and ex situ surface characterization. The corrosion product film that formed at 1.5 m/s for the 90/10 tube and at 0.5 m/s for the 70/30 tube showed the best corrosion resistance. For the 90/10 tube, a continuous film existed below 3 m/s and mainly inhibited a cathodic reaction. For the 70/30 tube, a continuous film existed in the range of 0.5-4.7 m/s and was more similar to typical passive film electrochemically, although it was cracked at 4-4.7 m/s. So, the "critical flow velocity" of the 90/10 tube was between 3 m/s and 4 m/s, and that of the 70/30 tube was beyond 4.7 m/s.