The present and future of zinc flake 15 May 2024

In the world of zinc flake systems, it's all about combination. Here, two different layers work together to ensure that steel components are reliably protected against corrosion and that the coating is equipped with additional properties. These two layers are a basecoat and a topcoat.

In automotive engineering, the construction industry, renewable energies, and many other industries, zinc flake coatings have been protecting components in a wide range of dimensions for decades. Despite a low coating thickness, usually only between 8µm and 20µm, it offers a high level of cathodic protection.

The functions of the different layers

Basecoat and topcoat fulfil different functions in a coating system. The basecoat, which is applied directly to a component, determines the corrosion protection properties. It contains the zinc, which sacrifices itself in favour of the underlying steel if the surface is damaged. The topcoat is applied on the zinc flake basecoat and supports it. It increases the corrosion protection, by keeping corrosive media such as water, salts or chemicals away from the surface. However, customer requirements go beyond just corrosion protection. Therefore, a topcoat also provides functional properties of the system. Depending on the component and the demands, a topcoat can provide a coating with different, individually varying characteristics. It can be used, for example, to achieve resistance to mechanical or chemical stresses or abrasion. The colouring is also realised through the topcoat. When coating components with metric threads, a defined coefficient of friction can be set as well.

With DELTA-PROTEKT® TC 502 GZ, DÖRKEN has developed a product that focuses particularly on this property.

What the new topcoat can do

The experts at DÖRKEN have developed a solution that cures at room temperature within 60 minutes. After seven days, the coating is cross-linked and impresses with very good cathodic corrosion protection properties.

The topcoat has been specifically developed for the coating of bolts and nuts. The coating generally depends on the geometry of the component, but the spray process and dip-spin process are recommended. With the topcoat, a particularly narrow friction coefficient window can be set -even with multiple tightenings. Overall, it achieves a high level of process stability.

Not only have heavy metals such as chromium, lead or cadmium been avoided in the formulation – the product is even completely free of per- and polyfluoroalkyl substances (PFAS). The overall package of DÖRKEN’s latest innovation is topped off with an appealing silver finish and increased corrosion protection.

DÖRKEN will be exhibiting at Surface Technology Germany in Stuttgart from 4th to 6th June where employees will be available to answer all questions in hall 1, booth C26.
Becca England Assistant Editor t: +44 (0) 1727 615 413

Becca is the latest member to join our team and is eager to get stuck into the world of fasteners. She brings an enthusiastic and fresh outlook on what we do editorially and will be leading our social media activity – including sourcing material, editing articles and posting online.