Coating process

Coating processes are surface technology processes in which workpieces are provided with an additional layer or their surface is specifically transformed in order to achieve certain properties such as corrosion protection, wear resistance, electrical conductivity or a decorative effect. They are divided into different main groups according to the type of layer formation:

• Mechanical coatings: Application by physical-mechanical methods, such as thermal spraying, flame spraying or build-up welding. This involves applying foreign material to the surface.

• Physical processes: Coating generation from the gas phase, for example by PVD (physical vapor deposition), CVD (chemical vapor deposition), vapor deposition or sputtering.

• Chemical processes: Deposition of layers by chemical reactions without an external power source, such as electroless nickel or electroless copper.

• Galvanic processes (electrolytic deposition): Production of metallic coatings by current in an electrolyte bath, for example chrome plating, nickel plating or copper plating.

• Organic coatings: Application of organic layers, for example by painting, powder coating or coating with plastics.

• Conversion processes (conversion coatings): Formation of protective or functional layers by chemical or electrochemical conversion of the material surface itself, for example phosphating, chromating, passivating or anodizing of aluminium.

This classification enables the processes to be categorized systematically and illustrates the different active principles of coating formation.