An XPS Study of the Behavior of the Protective Layer on Aluminum-Brass Condenser Tubes^*

The behavior of the hydrotalcite-type mixed Al, Mg, Zn hydroxide layer formed on aluminum brass condenser tubes in seaside power stations has been studied using X-ray photoelectron spectroscopy. This layer, which forms underneath an outer FeOOH layer deposited from FeSO₄ additions to the cooling water, is shown to have a buffering capacity, adsorbing and losing Mg⁺⁺ with pH changes. This capacity varies depending in part on tube history, particularly periods of drying out that may alter the crystalline form of the compound.