ANIONIC ALUMINUM ACTIVATION IN THE PRESENCE OF ADSORBED ION-EXCHANGERS

A metal-depassivation model involving the migration of L(-n) anions th rough an oxide-hydroxide film (the ion-exchange mechanism of adsorptio n and migration through an ion-exchange layer to Al-Al2O3 phase bounda ry) is considered. Negative (iminodiacetate- and sulfosilanes) and pos itive (ammonium- and amine-containing silanes) adsorption monolayers a re synthesized on an aluminum surface. Electrochemical and corrosion t ests of the layers in Cl- containing electrolytes show that negative r adicals stimulate inhibition, while positive radicals lead to depassiv ation. The surface charge and potential psi1 affect the pitting-corros ion potential and depassivation susceptibility of aluminum in chloride -containing electrolytes.