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 plants was studied using X-ray photoelectron spectroscopy. This layer, which forms underneath an outer FeOOH layer deposited from FeSO//4 additions to the cooling water, is shown to have a buffering capacity, absorbing and losing Mg** plus ** plus 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.