anodisation

Anodisation, also known as anodic oxidation, is an electrochemical process used to increase the thickness of the natural oxide layer on the surface of metal parts. It is most commonly applied to aluminium, but can also be used for magnesium, titanium, and tantalum. The process involves immersing the metal part in an electrolytic solution, typically an acid, and then passing an electric current through it. The metal part acts as the anode, while a cathode is also present in the solution. The electric current causes oxidation to occur at the surface of the metal, forming a thicker, more durable oxide layer.

The resulting oxide layer is porous and can be dyed or sealed to provide a variety of colours and finishes. Anodisation offers several benefits, including enhanced corrosion resistance, improved wear resistance, and increased hardness. It also provides a good base for painting or bonding. The thickness and properties of the anodic oxide layer can be controlled by adjusting factors such as the electrolyte composition, temperature, current density, and time. Different anodising processes exist, such as chromic acid anodising, sulphuric acid anodising, and phosphoric acid anodising, each yielding slightly different properties in the oxide layer. This process is widely used in industries such as aerospace, automotive, architecture, and consumer electronics for decorative and functional purposes.