Zinc flake coatings from DÖRKEN: Highly reliable protection against corrosion

You can count on the expertise and experience of Europe’s market leader in microlayer corrosion protection systems: A zinc flake system from Dörken MKS meets all complex requirements.

Since DÖRKEN developed its first application of zinc flake coating in 1989, continuous further development and innovation have made us the reliable partner for corrosion protection with efficient zinc flake coatings.

A zinc flake coating is a modular system consisting of a basecoat and a topcoat. The individual components can be combined to precisely satisfy characteristic requirements (specific coefficient of friction, chemical resistances etc).

• Basecoat: The basecoat is the zinc flake coating and is applied directly to the substrate to be treated. This base layer determines the corrosion protection properties. The zinc content provides a high level of cathodic corrosion protection. For bulk materials, such as thread-rolling screws, application by dip spin process is typical, for larger components the spraying process (manual or by robots) is recommended
• Topcoat: The topcoat complements the properties of the basecoat, and gives the coating additional multifunctional properties. In addition to corrosion protection, the topcoat protects against chemical and mechanical impacts and is responsible for the:
  • Requirements of coefficient of friction
  • media resistance
  • weathering resistance
  • appearance
  • and other individual requirements

For more than 30 years, zinc flake coatings have been used in the automotive industry, among others, but the strengths of this coating are also increasingly being used for construction machines and in the field of renewable energy.

An overview of the main advantages of zinc flake coatings: 

• Cathodic protection: The zinc flake coating functions as a metallic layer consisting of many small flakes. In most cases they consist of a combination of zinc and aluminium flakes bound together through an inorganic matrix. Since the sacrificial effect of zinc actively protects the component from environmental and chemical influences, the zinc flake coating offers a high level of cathodic protection.
   
• Low layer thickness: The total layer thickness of the coating is on average only 8-20 µm and is therefore thinner than a human hair. Compared to other corrosion protection systems such as powder coatings or hot-dip galvanizing, the zinc flake coating is almost invisible, but nevertheless achieves a protective effect of over 1,000 hours against base metal corrosion in the neutral salt spray test in accordance with ISO 9227.
   
• High accuracy of fit: Reliable corrosion protection with a very thin texture: Zinc flake systems are ideal for components whose standards place high demands on fitting accuracy, for example, screws with metric threads.
   
• No stress corrosion cracking: With zinc flake coating, no hydrogen is provided during the application process, which prevents application-related, hydrogen-induced stress corrosion cracking. Zinc flake systems are therefore the best choice for high-strength steels (Classes 10.9 and higher).
   
• Attractive appearance: It is possible to adapt the visual appearance of the zinc flake coating to customer requirements through the selection of the topcoat. By overpainting with a paint that does not damage the corrosion protection of the zinc flakes, different colour variations are also possible, for example, for marking different components.

The choice of the suitable process for corrosion protection always depends on your individual requirements. As an expert in corrosion and surface protection, Dörken MKS offers other proven processes in addition to zinc flake systems, such as:

• Electroplating
• Cathodic dip coating (KTL)
• Coil Coating

What is a zinc flake?
A zinc lamella is a corrosion protection coating composed of zinc and aluminum. This compound is held together by an inorganic matrix. If a coating of zinc flakes is applied to a component, this layer shields the metal from external influences.
When applied correctly and over the entire surface, such a zinc flake coating provides durable and long-lasting protection against corrosion even at low coating thicknesses.

How does a zinc flake coating work?

The zinc flake coating acts like a protective layer between metal/steel and the environment. The zinc portion of the coating acts here as active, cathodic corrosion protection - the zinc "sacrifices" itself and is gradually removed over time by environmental influences. However, the metal underneath the zinc flake coating is not affected by these processes. By completely isolating the metal/steel from the environment, the coated object permanently retains its properties without being affected by corrosive influences.

Why do I need a zinc flake coating?
A professionally applied zinc flake coating prevents the respective metal parts from being exposed to the environmental influences around them without protection. This brings with it a number of advantages:

• Longer durability of the components
• High corrosion protection
• Flawless optics throughout
• Lower maintenance costs

The use of a zinc flake coating thus helps to reduce corrosion-related damage to components to a minimum. This makes structures more durable and significantly reduces the financial costs of refurbishment measures.

In which areas are zinc flake coatings used?Zinc flake coatings have already established themselves as popular corrosion protection solutions in numerous industries. For example, they are used in the following industries:

• Automotive industry
• Agricultural machinery
• Construction machinery
• Renewable energy (wind parks)

These are just some of the most prominent industries - a zinc flake coating can be used almost universally thanks to its practical properties. We would also be happy to advise you on your application options.

How can a zinc flake coating be applied?
There are various processes for applying a zinc flake coating to components. These include the spray process, the dip-spinning process, the rack-dip-spinning process and the dip-drawing process. Which zinc flake coating process is used in each case depends on both the number of components and their size. For example, the dip-spin process is typically used for bulk material, but larger components are usually treated by the spray process.