INFLUENCE OF BATH COMPOSITION ON ALUMINUM CORROSION IN ALKALI CARBONATE MELT

The influence of sodium (Na) additions with different chemical natures (sodium peroxide [Na2O2] and sodium chloride [NaCl]) on the mechanism and kinetics of aluminum (Al) corrosion was investigated. Auger elect ron spectroscopy, x-ray photoelectron spectroscopy, and x-ray structur e spectroscopy were used to analyze the corrosion products. Na2O2 prom oted formation of more compact, less defective films. At high temperat ure, the introduction of peroxide into the salt phase resulted in the emergence of different oxygen (O) ions and a film with higher O conten t NaCl additions destroyed the coating through formation of pits and l ocal solutions of oxide layers. The greater the concentration of activ e ions was, the less the initial depassivation potential was. Increase s in anodic polarization and concentrations of chloride ions (Cl-) dim inished induction time. Films consisted only of alpha-LiAlO2, a crysta l modification of lithium aluminate.