5.6 Corrosion
Corrosion refers to the reaction of a material
with its environment, resulting in a measurable change in
the material and capable of leading to corrosion damage (DIN
50 900). Originally, the term "corrosion" was only
applied to metals, but nowadays it is generally used for any
materials, including polymers, glass and ceramic.
Corrosion refers to the chemical attack of a medium on a material.
In contrast, abrasion is defined as the mechanical interference
of a solid body (the opposing body) with the main body of
a tribological system. In most cases, corrosion increases
the level of any abrasive wear.
In comparison to metals, ceramic materials may be considered
resistant to corrosion, because their corrosion rates are
a great deal lower than those of metals. There are significant
differences in the types of corrosion and corrosion resistance
between the different groups of ceramic material (silicate,
oxide and non-oxide ceramic). Whereas corrosion in metals
is an electrochemical process, the solubility of the material
is the determining factor in the level of ceramic corrosion.
The chemical composition and the microstructure are the key
factors for low corrosion rates.
|
|
