open access

https://hdl.handle.net/2115/57823

The effects of film thickness and incorporated anions on pitting corrosion of aluminum with barrier-type oxide films formed in neutral borate and phosphate electrolytes

英語

Ion selectivity

2014-02

Springer

Journal of solid state electrochemistry

18(2)

369-376

The pitting corrosion behavior of high-purity aluminum covered with barrier-type anodic films, which are formed in neutral borate and phosphate electrolytes, has been examined in 0.5 mol dm(-3) NaCl solution at an applied potential of -0.6 V versus Ag/AgCl, which is slightly nobler than the pitting potential of -0.64 V in the same solution. The pitting current density, i (p), increased with time after an incubation time, t (i). The double logarithmic plot of i (p) and polarization time, t, reveal two straight lines, which are separated at the time, tau. The slope becomes larger after tau for the specimens anodized in the phosphate electrolyte, while it becomes smaller for those in the borate electrolyte. Both the t (i) and tau increase with the thickness of the anodic films, and at the similar film thickness, they are much larger for the anodic films formed in the phosphate electrolyte than for those in the borate electrolyte. The corrosion process can be divided into three stages: the incubation period up to t (i), the pit nucleation period before tau, and the pit growth period after tau. We have discussed the different pitting corrosion behavior of the aluminum specimens covered with the anodic films formed in the borate and phosphate electrolytes in terms of ion selectivity of the anodic films.

学術雑誌論文

Accepted Manuscript

The final publication is available at link.springer.com

1432-8488