Ullmann's Encyclopedia of Industrial Chemistry

Practical experience with industrial equipment, machinery, and plant has shown that components have only limited service lives. Damage and ultimate failure of the component can occur as a result of changes in the material that originate at the surface, even if the components are designed such that long-term action of the forces alone causes neither fracture nor undue deformation.

If the reactions responsible for the damage are of electrochemical or predominantly chemical nature, the term corrosion is normally used, whereas mechanical damage to the surface of the component is defined as wear. Attempts to avoid a loss of material due to wear, or at least to reduce the loss, concentrate on making the affected surface more resistant to wear. This can be achieved by mechanical, thermal, or thermochemical treatment of the surface or by applying or depositing metallic coatings. Under some circumstances the wear conditions can be changed by design measures so that the danger for the affected component surface is eliminated or reduced to a tolerable level....




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