Repassivation Investigations on Aluminium: Physical Chemistry of the Passive State

Abstract

We show the temporal change in repassivation mechanism as a time-dependent linear combination of a high-field model of oxide growth (HFM) and the point defect model (PDM). The observed switch in transient repassivation current-decrease under potentiostatic control occurs independently of the active electrode size and effective repassivation time for all applied overpotentials.For that,A mathematical model combines the well established theories of oxide-film formation and growth kinetics, giving insight in the non linear transient behaviour of micro-defect passivation.According to our findings, the repassivation process can be described as a charge consumption via two concurrent channels. While the major current-decay at the very beginning of the fast healing oxide follows a point-defect type exponential damping, the HFM mechanism supersedes gradually, the longer the repassivation evolves. Furthermore, the material seems to reminisce former laser treatments via defects built-in during depassivation, leading to a higher charge contribution of the PDM mechanism at higher pulse numbers.

Pulsed laser ablation and incubation of nickel, iron and tungsten in liquids and air

“…Laser processing in liquids has attracted attention because of potential applications in surface cleaning, etching, welding, drilling, cutting, and micromachining of metals, alloys, polymers, semiconductors, glasses and ceramics [1,2]. Laser ablation of metals in liquids enables the insitu study of corrosion and repassivation processes [3,4] as well as the production of biocompatible nanoparticles for medical and catalytic applications [5][6][7]. The pulsed laser generation of colloidal metal nanoparticles (e.g., Ag, Au, Pt, Pd, Cu, Fe, Ni, W) in distilled water and organic solvents attracted much attention in the past two decades [7][8][9][10][11][12][13][14][15][16][17].…”