Effect of phosphorus content of α-brass on its corrosion resistance in aggressive soil: experimental and characterization studies

The effects of introducing small amounts of phosphorus (P) into α-brass on its corrosion behavior in Azrou soil were examined. Three α-brasses (denoted EM1, EM2, and EM3) with different P contents were studied in this work. These brasses were investigated using Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization (PDP) plots and Scanning Electron Microscopy (SEM), whereas the chemical composition was determined by energy-dispersive X-ray spectroscopy (EDS). The experimental results showed that the most resistant of the three α-brasses to corrosion in this soil was EM3. Moreover, the presence of P in the α-brasses decreased their corrosion rates and increased their corrosion resistance, i.e., the polarization resistance of the brasses to corrosion increased with the P content of the brass. The maximum polarization resistance, Rp = 851 kΩ cm2, occurred with a P content of 0.137%. The observed changes in surface morphology with increasing P content and the corrosion products deposited on the brass surface were examined by X-ray diffraction. EM3 coupons in the studied soil only showed base metal peaks, demonstrating that EM3 is highly resistant to corrosion.