The room temperature curing zinc flake: A new dimension of cathodic corrosion protection

Zinc flake coatings effectively protect components from corrosion. The coating is usually cured in an oven after application. However, this is not possible for all components for various reasons. This is where the room temperature curing zinc flake?from D?RKEN comes into play.

Whether humidity, chemicals or temperature fluctuations: Components of all kinds, from spring band clamps to car chassis, have to withstand a variety of weathering influences. Zinc flake coatings, which offer a high level of cathodic corrosion protection in thin layers from 10 μm, have proven their worth in protecting these parts. In this process, the less noble zinc sacrifices itself in favour of the more noble steel.

The coating is applied depending on the geometry of the component. For bulk materials such as bolts, the dip-process method is usually chosen; for larger components, spray application (manually or by robot) is suitable. In order to achieve the full corrosion performance, the zinc flake coating is usually cured at temperatures from 180° Celsius.

High cathodic corrosion protection even without curing

However, this procedure is not suitable for every application. For this reason, the company D?RKEN from Herdecke has developed a zinc flake system that cures at room temperature. Energy savings are of great importance in the current world and economic situation. Due to the increased energy prices, classic curing processes are less economical than in the past. In addition, curing ovens for coated components always mean investment costs that could be reduced. The space requirement is also significantly reduced by the room temperature curing solution.

But what distinguishes the room temperature curing zinc flake coating in the first place? It convinces with its very good cathodic corrosion protection properties in constant and alternating tests. It is dried within 60 to 70 minutes and cured after seven days. Accordingly, the high temperatures required for curing are not needed. If required, the room temperature zinc flake can also be force-dried. This makes it suitable for industrial processes with short cycle times.

A practical, flexible and sustainable solution for cathodic corrosion protection

The solution opens up completely new possibilities for different types of components. These include, on the one hand, large, massive components that cannot be moved or do not have room in a standard curing oven. In addition, there are scenarios in which the components or pre-assembled component groups must not be exposed to high temperatures. This is the case, among other things, when these groups contain electrical components.

Last but not least, the room temperature curing zinc flake has another important advantage that has become much more significant in the last few years: The system produces fewer CO? emissions than the usual processes. With zinc flake coating, up to 60 % of the emissions can be attributed to the curing process, which can thus be reduced. The room temperature curing solution thus supports companies on their way to climate neutrality.

The new generation of the room temperature curing zinc flake

But of course, development at D?RKEN does not stand still. Based on its own findings coupled with feedback from the market, D?RKEN is working on making the room temperature curing zinc flake even better. With the new generation, the focus is particularly on overpaintability. Practical experience shows that overpaintability is one of the most sought-after properties. There is a wide range of compatible systems for this. Even with high coating thicknesses, good corrosion protection and low infiltration are guaranteed. After mechanical preloading by a 2 mm Sikkens scratch, no debonding can be detected starting from the scratch in the salt spray test according to DIN EN ISO 9227 at a dry film thickness of 100 μm. Due to its strong adhesion and good cohesion, the coating also convinces with its abrasion resistance.

The fields of application for the new two-component coating are manifold. In addition to heavy corrosion protection in the bridge and building sector, the coating of components on cars, including vehicle chassis, is also possible.

The research team at D?RKEN is also currently working on a fitting top coat. This will also be room temperature curing and can be coloured according to customer specifications, for example in all RAL colours. The water-based topcoat can be coated by spray application with layer thicknesses from 50 μm. It also performs well in the salt spray test (1440 h) without red rust and debonding starting from the scratch.?

If you would like to learn more about this topic, our Product Engineer Markus Nowak will be happy to hear from you!