A knowledge of the structural characteristics of corrosion products can provide the corrosion scientist with a better understanding of factors that control chemical and/or electrochemical processes during the destructive attack of materials. In most systems, the surfaces of construction material are exposed to gaseous or liquid environments and experience thermodynamic driving forces which change their chemical and structural composition. The rate of this conversion, however, depends to a large extent upon the characteristics of the products that form, which in many systems slows the rate sufficiently that the product may be considered a protective coating or passivating film. Unfortunately, this is not true for all systems, and frequently the protection is destroyed through changes that occur in the substrate, the coating or the environment as the exposure time is increased, resulting in destructive attack of the substrate or base material. Through a detailed structural characterization of the corrosion product at sites of failure, the cause of destructive attack can be identified and thus aid corrosion scientists in selecting corrective measures. It is not the purpose of this paper, however, to resolve corrosion problems or recommend corrective measures, but instead this paper is intended to present some insight into the structural properties of corrosion products and methods for acquiring these data.
