By Lammert de Boer, global director for Zinklad, DecoKlad & XMAPP, MacDermid Enthone Industrial Solutions
According to Marklines1, by 2023, some 20% of all vehicles produced will be electric (versus gas), bringing with it new challenges for fastener coating engineers working on electric vehicles. Considerations include electrical conductivity, the use of lighter materials to maximise vehicle range per charge, contact corrosion, galling, premature corrosion and warranty.
Specifiers need to select the right surface coatings for fasteners in electric vehicles to ensure effective grounding, resistance to galvanic corrosion, and predictable coefficient of friction coupled with excellent corrosion protection. These factors must also be consistent throughout an electric vehicle’s life.
Keeping up with an evolving electrical landscape
Electric vehicles and hybrids will naturally need more electric and electronic components. Printed Circuit Boards (PCBs), integrated circuits, and connectors, are increasingly being used for this purpose, but reliable ground connections are also required. Coatings on fasteners for electric vehicles will need to be extremely reliable in terms of preventing screws from insulating – this is a critical factor in the ever increasing use of electrical components in today’s vehicles. Components with surface protection must therefore offer the longest possible protection against wear and corrosion to avoid the risk of electrical properties changing over time.
Lightweight construction is also essential for electric vehicle development. However, light metals pose a further challenge for surface technology – not only do they have to be protected against corrosion, but their negative potential can also cause galvanic corrosion when they are installed with a material that has different electrochemical potential. Another approach to lightweight construction is the use of high strength or ultra high strength steel fastener materials. For these materials, pre-treatment and surface protection systems must be selected based on their ability to minimise the risk of hydrogen embrittlement. This requires not only information about the respective components involved, but also detailed knowledge about connecting components, environmental conditions and stress in use. Typically, these decisions need to be made during the design phase.
- IC Only: Internal combustion only
- MHEV: Mild hybrid electric vehicle
- FHEV: Full hybrid electric vehicle
- PHEV: Plug in hybrid electric vehicle
- BEV: Battery electric vehicle
- EREV: Extended range electric vehicle
- FCV: Fuel cell electric vehicle
Source: https://www.marklines.com/en/forecast/index
Supporting automotive fastener engineers
It is a crucial challenge for the automotive industry to both innovate and adopt the use of proven, consistent surface coating technology solutions that will support specifiers and fastener engineers to meet the requirements of electric vehicles. MacDermid Enthone Industrial Solutions has introduced ZinKlad® 750 – the latest standard from the world-class ZinKlad portfolio developed for coatings of steel fasteners in electrical grounding applications.
ZinKlad 750 is a tin-rich sacrificial coating, which passes stringent automotive cyclic corrosion testing and 1,000 hours of neutral salt spray, while still being able to perform its electrical grounding functionality. After application of a trivalent chromium passivate, a unique double top coat provides both exceptional corrosion resistance and a consistent coefficient of friction. On fasteners, the coating retains its finish over extended periods of time without the presence of excessive white or red corrosion products, thus maintaining metal-to-metal contact.
ZinKlad 750 has completed the GMW3200 conductivity test for fastener grounding applications and meets the hydrogen embrittlement requirements of GMW4700. ZinKlad 750 also offers a combination of unrivalled corrosion resistance, low electrical resistance, good conductivity and reduced formation of corrosion products. The benefits of this include maintaining conductivity and low coefficient of friction to prevent galling during fastener assembly. These benefits are being realised on today’s highly connected passenger vehicles. Using this coating, the industry will be able to deliver high-quality and consistent fasteners, which meet tomorrow’s challenging requirements.
1 https://www.marklines.com/en/forecast/index
Will joined Fastener + Fixing Magazine in 2007 and over the last 12 years has experienced every facet of the fastener sector – interviewing key figures within the industry and visiting leading companies and exhibitions around the globe. Will manages the content strategy across all platforms and is the guardian for the high editorial standards that the brand is renowned.
