Effect of Cyclic Temperature on the Corrosion Behavior of (α+β)-Brass (CuZn36Pb2As) and α Brass (CuZn21Si3P) in Tap Water

Characterizing the corrosion behavior of pipeline brasses undergoing cyclic temperature variation is essential for the prevention of degradation. Two brass alloys, (α+β)-brass and α-brass, were studied to evaluate their surfaces in drinking water at constant and cyclically varying temperatures. Both alloys were immersed for 1h in drinking water at nine different temperatures, starting at 278 K, and going up to 318 K. The two copper-zinc alloys were also immersed for 96 h at both critical temperatures (278 K and 318 K) and room temperature. To study the effect of cyclic temperature variation, immersion tests at cyclically varying temperatures were done between the two critical values for 4 cycles. The results of an integral electrochemical analysis using (PDP) and (EIS) revealed that the two alloys react differently under the same experimental conditions. The corrosion rate has approximate values for the cyclical temperature change of 3.04 µA cm-2 for α-brass and 3.26 µA cm-2 for (α+β)-brass. Impedance tests also show that α-brass tends to hold up remarkably well with 130.5 KΩ.cm² of polarization resistance versus 94.1 KΩ.cm² for (α+β)-brass. Similarly, degradation was observed in both alloys during cyclic temperature changes. The etched surfaces of the alloys were examined using SEM-EDX to obtain a clearer understanding of the surface morphology. The SEM images showed that an oxide film protects the surfaces. Monitoring of Cu2+ and Zn2+ ions in the electrolyte by ICP provided a detailed idea of the leaching of these metals.