Corrosion & Environmental Degradation
Table of Contents
· Corrosion is a general term used to describe various interactions between a material and its environment leading to a degradation in the material properties.
·Interaction with ambient oxygen can cause the formation of oxide layers via diffusion controlled growth. These may passivate the material against further oxidation.
· In a wet environment, aqueous corrosion can occur due to electrochemical processes which depend upon metal ion transport and reaction. Gradients of metallic and electrolytic ion concentrations, temperature, ambient pressure, and the presence of other metals, bacteria, or active cells, all influence the corrosion rate.
· Electric fields applied to corroding systems can accelerate or inhibit the rate of corrosion or material deposition. Galvanic corrosion between different metals in an aqueous environment is due to the electric field arising from the different electrode potential of the two materials. External fields may enhance or supress this corrosion.
· In all of these reactions, electron and ionic transport occurs. The following sections will be concerned with these processes and the effect of conditions on the corrosion rates.