Scientists at Fraunhofer IWM have developed and tested a substitution chain for lubricants and seals containing PFAS in a project funded by the state of Baden-Württemberg and a Fraunhofer project. This allows suitable PFAS-free materials solutions to be efficiently identified and evaluated.
"The spirits I summoned, I now cannot get rid of," cries the sorcerer's apprentice in the poem of the same name by Johann Wolfgang von Goethe, written in 1797. In one of the great technological and scientific dilemmas of our time, PFAS are the spirits. They are extremely temperature-stable and chemically resistant, and we enjoy their advantages, such as durability as well as water, grease, and dirt repellency in many everyday products and especially in highly stressed materials and systems. Examples include textiles, cookware, sports products, vehicles, pumps, drives, and much more. Many thousands of per- and polyfluoroalkyl substances (PFAS) are key to performance and reliability in technical systems due to their molecular structure and low surface energy.
On the other hand, the health risks of PFAS compounds are obvious: due to their chemical resistance, PFAS compounds have a very long lifespan and enter the human body via the environment, where they accumulate and can promote the development of diseases. At the EU level, work is underway on PFAS regulations and bans, which are to come into force gradually beginning in 2026. Regardless of the status of regulation, a strong market dynamic has emerged, and many companies are becoming increasingly aware of the issue: Which products contain PFAS? How will supply chains change if PFAS are phased out? What does phasing out PFAS mean for product costs? What investments in manufacturing would be necessary for a transition?
One of many industrial sectors concerned about the PFAS issue is manufacturers of pumps, gearboxes, guides, and bearings, i.e., components of classic mechanical engineering. In this sector, PFAS-containing lubricants ensure energy efficiency, PFAS-containing sealing rings withstand high operating temperatures and guarantee functionality, and PFAS-containing additives in plastics are responsible for high wear resistance.
When you consider how many lubricants there are, how many elastomers for seals, and how many types of plastics, it quickly becomes clear that there is no single optimal PFAS-free solution. Any substitute must meet customer requirements, be economical to manufacture, be reliable, and ultimately also have a competitive cost structure.
This is where the PFAS-free project, funded by the state of Baden-Württemberg, comes in. The tribology experts at Fraunhofer IWM in Freiburg have designed a substitution chain that allows PFAS replacement solutions to be approached gradually, efficiently, and in a system-specific manner. This was tested using the example of PFAS-free lubrication for a planetary gear. In the PureWaterSeal development project, funded by the Fraunhofer Future Foundation, PFAS-free elastomer seals were developed and tested. The test results from the evaluation of alternative materials combinations form a digital knowledge base that helps to save time and money in future PFAS substitutions.
In terms of materials technology, the combination of lubricants with friction-reducing coatings plays a fundamental role in substitution approaches. In order to compensate for or even improve the loss of performance resulting from the elimination of PFAS, coating solutions made of diamond-like carbon DLC were developed, varied, and tested in combination with various lubricants. In the case of elastomer seals, the mix of pretreatment of the sealing material, the adhesive strength of the layers, and the wear resistance was optimized. For both applications—lubrication of miniaturized planetary gears and PFAS-free sealing rings—attractive substitution solutions were identified and qualified.
In Goethe's poem, it is the old master who banishes the spirits. In the case of PFAS, this option is out of question. Most tribological systems such as bearings, seals, and lubricants are optimized to their load limits for economic reasons, which is why PFAS substitutes are individual solutions that require a case-by-case system analysis. The substitution chain that has been developed can facilitate this process.
Fraunhofer Institute for Mechanics of Materials IWM