Synergistic Behavior of Lead-Free α-Brass (CuZn21Si3P) and (α + β)-Brass (CuZn36Pb2As) During and After Erosion-Corrosion Test at Various Angles in Simulated Drinking Water

Synergistic erosion-corrosion behavior of two types of brass, (α + β)-brass (CuZn36Pb2As) and lead-free α-brass (CuZn21Si3P) was studied in simulated drinking water. A jet device was employed with various impingement angles (15°, 30°, 45°, 75°, and 90°) and a velocity of 11 m/s, using the eroding particle (SiO 2 ) of which concentration was 30 g/l. All tests were conducted in accordance with ASTM G119-09. Electrochemical Measurements and corrosion weight Loss tests showed that the maximum erosion-corrosion rate for both alloys occurred at an impingement angle of 45°. And the electrochemical corrosion rate increased with increasing the impingement angle and reached the maximal value at an angle of 90°. The interaction between corrosion and erosion could lead to a positive synergy effect representing 27% of total degradation (erosion-corrosion) for (α + β)-brass and 19% for α-brass. The total synergism was mainly an effect of corrosion on erosion, and the dominated regime was a synergistic effect at all impingement angles. The SEM/EDX showed for α-brass, erosive tracks, and some protective layers, and for (α + β)-brass, erosive tracks, craters, and deformed lips. After 1 h of erosion-corrosion tests, both alloys regenerated a protective layer at different impact angles. α-brass regenerated the protective oxide layer better than (α + β)-brass. α-brass is more resistant to erosion-corrosion than (α + β)-brass thanks to its chemical compositions and its mechanical characteristics, mainly hardness and yield strength.