Corrosion Effects on Field Penetration Through Apertures

Abstract

The penetration of electromagnetic fields through an aperture caused by the faying join of a door or cover in a shielded barrier is dependent upon the conductivity of the join and the size of the aperture. It is common practice to plate the faying surfaces and place an EMI gasket between the joining sur­ faces to increase the conductivity and reduce the effective aperture of the join. In selecting the plating and gasket materials, corrosion control is usually of utmost concern, where the corrosion of concern is usually that which causes deterioration of the structure (i.e., oxidation of the base material). Oxi­ dation of the plating and gasket material can, however, cause the conductivity of the join to increase significantly. As a result, the penetration of electromagnetic fields through the aperture can increase with time as oxi­ dation of the platings and gasket material take place.