PORE STRUCTURE IN ANODIC AL2O3 FILMS

The structure and properties of anodic Al2O3 films grown in a borate solution have been investigated using electron microscopy, spectrophotometry and electrical techniques. The films can show typical barrier or porous growth according to the temperature of the solution. This change is attributed to increased oxide solubility at higher temperatures. The barrier" films show a texture and it is suggested that they differ from "porous" films only in the rate of thickening at constant applied voltage. The pore structure of films can alter considerably during film growth and the metal purity can affect the rate of pore initiation. The properties of the film material can be drastically changed by growth at very high c.ds. © 1969."