Physical boundary conditions, corrosion

Corrosion may be defined as the physical and chemical alteration of a material due to its interaction with the environment of interest. It must be emphasized that corrosion resistance is not a material property but a system property and real environments have a high variability in both chemical and physical boundary conditions. 

But even under steady-state conditions there is a profound influence of physical boundary conditions on corrosion behavior. The most widely known example of this is the boundary between active and passive oxidation of silica-formers. The classic modeling has been done by Wagner [11] for silicon. 

Other approaches to active corrosion prediction utilizing thermochemical calculations [8,17,18] require the experimental determination of effective parameters. They show both the importance of physical boundary conditions and the extremely low level of partial pressures at which active corrosion is potentially dangerous. 

A lubricant is any material that can be placed between surfaces to lessen friction. The purpose of a lubricant is to reduce the frictional resistance between two contacting surfaces forced to slide over one another, to minimize wear, and prevent corrosion. Antiwear agents produce a surface fihn either by a chemical or by a physical adsorption mechanism to minimize friction and wear under boundary lubrication conditions. 

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