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Horn Blog

Coatings

July 2021
09
Author: paulhorn
Company: Hartmetall-Werkzeugfabrik Paul Horn GmbH
Coatings

We come into contact with them every day – coatings. Varnish, electroplating or other technical coatings. They inspire passion and recognition in automotive brands; in technical applications they increase performance and durability.

A coating modifies the surface properties of a component

No matter where they are going to be used, coatings all have one thing in common: a coating modifies the surface properties of a component. Way back in ancient times, people already understood the benefits of using coating products to protect against corrosion. For example, coatings like shellac were used on wood.

Protection against external influences

One of the most important purposes of a coating is to protect the material from external influences. This includes oxidation and corrosion protection coatings, wear protection coatings, thermal insulation coatings and decorative coatings. Coatings are applied by varnishing, electroplating, hot-dipping, sintering, using the PVD/CVD method or thermal spraying. Technical and economic factors need to be taken into account when it comes to selecting the right process.

According to DIN 8580, coating is one of the main groups of manufacturing processes in production technology. It defines the application of a substance to the surface of a workpiece. This process is referred to as coating. Coatings can be thin or thick and can also consist of several cohesive layers.

However, coating techniques differ significantly in terms of how the coatings are applied. The initial state of the coating material is a way to distinguish between the methods, including gaseous, liquid, dissolved and solid.

Gaseous processes

Gaseous processes are used to coat precision tools. In this case, there is a difference between physical and chemical vapour deposition. HORN uses the PVD technique (physical vapour deposition) for its tool coatings. PVD is a process which involves the coating material being vaporised by electrons, laser beams or arc discharges. The vaporised material covers the workpieces that need to be coated, which results in a layer being formed. The coating composition can be influenced by the supply of reactive process gases. This results in nitrides or carbides or mixtures of the two being deposited during the coating process. PVD coatings significantly increase the service life of cutting tools.

Diamond coatings

Chemical vapour deposition (CVD) also comes into play in tool coating. This method, for example, allows diamond coatings to be applied to carbide tools and it can even produce monocrystalline diamonds. Gases such as methane are used as the carbon source (diamond is 99.99 percent carbon).