Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


Thermochemical Coating

Last updated: September 19, 2017

What Does Thermochemical Coating Mean?

A thermochemical coating is largely composed of a substance called chromium oxide. It is bonded to the substrate through crystallography and offers substantial corrosion and wear resistance.

This type of coating can be applied on almost all types of base materials such as stainless steel, titanium and cast iron. It takes the form of a slurry, which can be applied straight to a metal substrate. As it undergoes several cycles of thermo processes, the slurry becomes dense and forms a non-porous ceramic substance that is bonded chemically to the substrate.

It offers a coating without flakes or cracks and is resistant to most acids as well as seawater. Notable properties of this coating are is its extreme hardness and ability to resist temperatures up to 700°C without requiring modification.


Corrosionpedia Explains Thermochemical Coating

One example of thermochemical coating is ceramic coating. It can be applied on a metal substrate in order to prevent corrosion and any form of damage brought by metal separation caused by other metal parts and electrolytes. This type of coating offers erosion, thermal and corrosion protection. It also provides an impressive cosmetic appearance. Typical forms of ceramic coatings are manufactured on slurry and applied on surfaces with the aid of successive heating. The thickness of the coating is usually around 4mm.

One variation of ceramic coating is vitreous enamel or porcelain enamel. This is produced by glass fusion into a metal substrate. The part that is coated is then fired to develop superior adhesion strength. Another form is the anodizing coating, which is a form of oxide film achieved through the electrochemical process of oxidation. The thickness of this coating may be 4mm or more, compared to aluminum surface or oxide film.

Ceramic coatings can be applied on different external and internal surfaces like ports and holes. They offer the following benefits:

  • Low friction
  • Extreme hardness
  • Pore-free and dense corrosion barriers
  • Thermal cycling and shock resistant
  • No need for pre-grinding
  • Superior wear resistance
  • Superior bond strength
  • Most importantly, thermochemical coating can increase coating life by up to 10 times, even in the most corrosion-prone environments.


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