Definition - What does Coating mean?

Coating, in the context of corrosion, is the thin layers of a covering substance, deposited or applied on a surface of any object, mainly to improve its critical properties and to create a protective barrier against deterioration of the surface due to its reaction with its environment.

When used as a verb, coating is defined as the process of application of covering layers on the surface. The surface on which coating is applied is called as substrate.

The coating protects the substrate from deterioration due to electrochemical reaction with the environment.Thus it improves the useful life of structures, pipelines and other vital equipment, and eliminates some of the life threatening failures and costs related to repair and premature replacements.

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Corrosionpedia explains Coating

The term "coating" generally includes

  • thin metallic covering,
  • inorganic lining like glass and porcelain lining,
  • organic covering such as polymeric material, paint, varnish, and
  • optical film covering and etched or printed covering.
The coating may be applied to provide
  • abrasion resistance and scratch resistance,
  • fire resistance and heat resistance
  • insulation against flow of electric charge
  • sealing ability and wettability
  • improved physical appearance and aesthetics
  • corrosion resistance
  • resistance against general wear, erosion, pitting and cavitation
  • improved physical appearance and aesthetics
  • release or nonstick property

Some examples of coating are

  • The layers of anti rust and anti corrosion paint,
  • polymeric material and varnish applied on structures and pipelines,
  • adhesive tapes,
  • fabrics with waterproof lining,
  • extrusion coated components and
  • cermet covered jet engine components.
Substrate can be steel and other metals and nonmetals like fabric, paper, plastics and wood. Coatings are extensively used for the protection of pipes and structures buried in the soil and immersed under water, as in the case of offshore oil rigs and platforms and also those installed in corrosive environment.
This definition was written in the context of Corrosion

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