The Changes of Surface Potential and Built-in Charge in Alumina Films After the Anodization Process

Abstract

We have shown that the surface potential of anodic alumina films changes in time: immediately after the anodization process it was positively followed by the substantial decrease to negative values. Such variations of the surface potential can be associated with the negative built-in electric charge in alumina. The highest negative charge density occurs in the films formed in citric and phosphoric electrolytes.

Formation of Alumina Nanotubes and Jet Effect during High‐Voltage Local Anodization of Aluminum

“…As far as a wall of the pore (especially at the surface of the porous layer) is negatively charged, and the incoming negatively charged ions drift in the inner part of the pore, leaving the pore surface free for gas extraction (Figure 6). [25] Note that in the regimes of anodic alumina honeycomb formation about 80% of the heat energy being produced belongs to the Joule heat. [26] It is generated in the alumina barrier layer.…”

“…Aluminum from the substrate serves as a “nanofuel.” As far as a wall of the pore (especially at the surface of the porous layer) is negatively charged, and the incoming negatively charged ions drift in the inner part of the pore, leaving the pore surface free for gas extraction (Figure 6). [ 25 ]…”