Some Electrical Effects of the Adsorption of Water Vapour by Anodized Aluminium

Abstract

The equivalent parallel capacity Cp and resistance Rp measured between the aluminium base of an anodically formed oxide film and a porous conducting layer deposited on the exposed surface of the oxide vary considerably with relative humidity ρ. At low frequencies porous oxide films show a range of variations of Cp of the order of 1 to 100, increasing with ρ, and the corresponding range of variation of Rp is of the order of 1000 to 1. Non-porous oxide films show very much smaller variations. Both Cp and Rp decrease with increasing frequency f for porous films.