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E-Mobility: Challenge and opportunity for coating processes

E-Mobility: Challenge and opportunity for coating processes

When people think of electromobility, they first think of battery and fuel cell technology for alternative drive systems. It is forgotten that surface finishing also plays a decisive role in this context, because many accompanying effects can be significantly optimized with innovative coating technologies.

With the increased focus on e-mobility, alternatives to the classic car such as e-bikes and e-scooters are becoming increasingly important, especially for urban mobility. For manufacturers, this creates new challenges in the supply chain: from hybrid technology, lightweight construction solutions, advanced safety systems and autonomous driving to influences on acoustics and the service life of vehicles.

As the market is changing rapidly, flexibility is particularly important, as many of these new requirements can be met by selecting suitable coating systems. A few examples will illustrate this fact.

Acoustics in e-mobility

Vehicle acoustics deals with the modeling of sounds - both those inside the vehicle and those perceived from outside in the vehicle environment. From the passenger's perspective, the focus is on noise reduction, whereas from the external perspective, noise reduction is primarily concerned with safety aspects. The distinctive background noise of the combustion engine is eliminated with electric vehicles, and the acoustics of the electric drive train and operating noise come to the fore.

As a result, vehicle development has to meet the emotional needs of customers and at the same time reduce movement and vibration noise in a targeted manner. For this purpose, dry-lubricating bonded coatings in the form of polymer systems based on PTFE, PFA or FEP fluoropolymers as well as MoS2 or graphite are used. Well-known systems include Xylan®, Molykote®, Gleitmo®, Antifricor® and GLISS-COAT®. In addition, contact noises caused by vibration can be significantly reduced by using flock coating with cathodic dip coating (KTL) as the base layer. Further advantages of the pure flock coating are the compensation of manufacturing tolerances as well as noise insulation on metal and plastic surfaces.

Electrification

Electric vehicles are not only powered by electricity, but are of course also equipped with a variety of electrical on-board systems. While this improves performance and comfort, it also significantly increases power consumption. This goes so far that the usual 12 Volt are no longer sufficient for the on-board electronics and recently the so-called 48-Volt technology is increasingly being used.

The basic requirement for good electrical conductivity is high-quality contacts or connectors and busbars, ideally coated with tin, silver or gold. At best, combination layers with a diffusion barrier of copper and nickel are chosen, since these ensure good corrosion protection in addition to signal and current transmission. Due to the higher voltage of 48 Volt, the operating temperature of the fasteners rises to over 160°C, and for safe operation, silver coatings in higher layer thicknesses must be deposited on the components.

A professional coating is also crucial for the safe operation of large vehicle batteries, because efficient protective devices such as corrosion-protected battery housings can only be created with high-quality surface technology. Nickel plating with sulfamate nickel offers the advantage of solderability and weldability in addition to high coating thicknesses and a good adhesion base for combination coatings. In addition, investigations are currently underway to replace the graphite layer on the anodes of lithium-ion batteries with a tin layer and thus achieve a significant reduction in costs.

A frequently neglected aspect in connection with electrification is the transmission of high-frequency signals in the vehicle. In order for it to run without interference, good contacting is required, but also an effective reduction of interference sources. A multi-layer structure allows static charges on hard-anodized aluminum surfaces to be selectively dissipated and signal transmission interference to be reduced while at the same time providing electrical insulation.

Due to their high conductivity, silver-plated or tin-plated connectors are also indispensable for future standards such as autonomous driving or sensor-based hazard detection. Coating technology thus creates the basis for the safe operation of the on-board systems of the future.

Lightweight construction

The Achilles heel of e-vehicles is their current low range. Consistent lightweight construction can be used to counteract this by saving weight and using larger batteries. In addition to aluminum and high-strength steel, the higher-quality materials titanium and magnesium are used for this purpose, which in turn have to be coated for various reasons. For example, magnesium rims need a magnesium oxide coating for corrosion protection and to prepare them for wet paint or powder coating. High-strength steels can be used with very thin walls, but are therefore susceptible to corrosion damage and must be protected against this with effective coatings. With titanium, galvanic corrosion with other metallic materials, which can occur despite the formation of a passive layer, can be prevented by an oxide coating.

In order to save weight, most of the materials used in e-bikes are aluminum and magnesium. For example, an aluminum oxide coating on battery housings creates a primer for adhesives (as a common alternative to welded joints), and magnesium coatings provide improved wear protection, for example on gear wheels.

Service life and price structure of components

Due to the increasing electrification, the tuning of the service life of all components installed in the vehicle must be readjusted. In principle, electric vehicles can be used for longer because they have less wear and tear than conventionally powered cars and fewer components are installed overall. However, the longer service life is also expected by customers due to the higher acquisition costs. In the discussion on wear, the focus in future will be on other assemblies and the increase in corrosion protection classes for chassis components. In many places where low corrosion protection classes are currently sufficient, the focus will in future be on higher quality microlayer corrosion protection systems (zinc flake coatings) or electroplated nickel (sulfamate nickel) and electroless nickel (DURNI-COAT®). This will make the professional coating of a wide range of components even more crucial to success in the automotive industry.

  • Electric car battery with tinned plugs.

  • Electric car motor with silver-plated power plugs.

  • Electric motor in a modern car: The requirements for corrosion protection of the installed components are increasing.

Conclusion

With the increased demands on components for electric cars, the demand for high-quality coatings will increase significantly in the coming years, because efficient coating is already becoming noticeably more important in terms of production costs, the economic and long-term operation of vehicles and customer benefits.

Enquiry

If you would like to tell us something about the applications presented here, you are welcome to do so. Your enquiry, your comment, your wishes will be forwarded directly to your personal contact person.

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