What is Anodising?

May 27, 2021 4:41 pm


Anodising is a common electrochemical process which is often used to enhance the hardness or homogeneity of certain metal components. The process of anodising is achieved by passing a direct electrical current through a previously unaffected component whilst an inert compound is in contact with the part being enhanced. When the current passes through the component, the compound with which it comes into contact is coated on the surface with a thin layer of anodized oxide (anodized).

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This anodised layer hardens at a much faster rate than the component being improved, hence improving the component’s hardness. The oxide coating also ensures that the improvement of the part requires a smaller amount of work to achieve the same level of hardness as the component before it (the component being improved).

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Typical anodising processes, like those from Poeton include the use of sodium hydroxide solution, drain plug (Drain plugging Induction) and a Teflon coated cathode. Sodium hydroxide solution is commonly used as the main component of this process, however it can be supplemented with other chemical substances such as silicon carbide, magnesium oxide, boron and other metal oxides depending on the application needs. Drain plug (or Induction) can be a Teflon coated cathode or a ceramic film.

Both these processes will use a metal component immersed in a strong electrolyte such as sodium hydroxide solution in order to induce the hardening of component surfaces. Drain plugs and Induction can both be internal or external. External drain plugs are commonly used in the automotive industry where water can leak into the engine compartment.