No abstract

Zeta potentials of Al and Al alloy plates are measured to investigate the relationship between zeta potentials and the structure of surface oxide layers. It is clarified that the formation of Boemite on the surface results in zeta potential decrease. It is also revealed that the pH-zeta potential curves of Al-Mg-Si alloy plates are in fair agreement with those of complex oxide particles of MgAl2O4 that are considers to be a model of surface oxide layers of the alloy. The plate surface of Al-Mg-Si is more negatively charged than that of Al-Mg in aqueous solutions above pH 4.