Fraunhofer Institute for Mechanics of Materials IWMThe project aimed to develop sustainable alternatives to PFAS-containing lubricants for mechanical systems. PFAS are characterized by high thermal and chemical resistance but pose a significant environmental burden. The focus was on applications such as planetary gears with high load and speed requirements. Alternative lubricants and ionic liquids in combination with coatings were evaluated as possible solutions. The approach taken in this project is intended to validate and create practical, market-ready approaches for substituting PFAS lubricants in many other applications in the future.
PFASfrei: Substitution and avoidance of lubricants containing PFAS
Completed research project
Project description
Per- and polyfluoroalkyl substances (PFAS) offer unique properties such as high thermal and chemical resistance and are therefore used in mechanical systems under extreme conditions (temperatures, chemical environments, vacuum, food industry, etc.) where conventional lubricants are not sufficiently stable. PFAS are therefore very difficult to replace in such applications, and there are no patent recipes for their substitution. The project aimed to identify PFAS-free solutions and promote their substitution in mechanical applications.
Avoiding PFAS is an urgent necessity, but it also poses considerable challenges, as high-performance PFAS-based lubricants are indispensable in many applications. Even if exemptions for certain areas of application could be achieved in some appeals proceedings, the long-term development of more environmentally friendly and at the same time more efficient substitutes for as many areas of application as possible remains crucial. The project aimed to develop an efficient approach for evaluating substitution options for PFAS-containing lubricants in various areas of application based on a use case. The following sub-goals were pursued to this end:
- Identification of areas for action: Areas of application with a high need for substitution were analyzed, considering technical, ecological, and economic aspects.
- Development of application-specific solutions: PFAS-free solutions were identified for the selected use case, and alternative approaches, such as the combination of PFAS-free lubricants with diamond-like coatings, were defined.
- Experimental validation: The developed solutions were experimentally tested for functionality and suitability.
Work packages
Work package 1 – Specifications
For a planetary gear use case, a specification sheet was created to systematically define the requirements for PFAS-free lubricants and, if necessary, coatings for miniaturized drive systems.
Work package 2 – Coating
The focus was on the development and quality-assured deposition of diamond-like carbon coatings (DLC) as tribologically effective functional coatings in order to reduce the stress on lubricants in demanding applications (including planetary gear demonstrators) and to support the substitution of PFAS-containing lubricants.
Work package 3 – Lubricant selection and sampling
Suitable PFAS-free lubricants were selected for the planetary gear application and corresponding samples were procured for tribological and stability-related investigations.
Work package 4: Tribological qualification
The aim of the work package was to evaluate the tribological properties of the selected PFAS-free lubricants in comparison to PFAS-containing references. Friction behavior, wear resistance, and temperature stability were investigated in combination with and without DLC coating.
Work package 5 – Demonstration
The entire development process for PFAS substitution was digitally mapped and documented. In addition to the experimental testing of suitable lubricant/coating combinations in planetary gears, the results were recorded in a structured manner, evaluated automatically, and integrated into a digital tribology database in accordance with FAIR principles (Findable, Accessible, Interoperable, Reusable).
Transfer of project results to R&D services provided by Fraunhofer IWM
A structured workflow for the substitution of PFAS-containing lubricants is available. This workflow maps the complete development cycle:
- Data collection I: Definition of stresses and target values (specifications).
- Data collection II: Performance of model and component tests.
- Automated data evaluation: Python-based scripts process measurement data (e.g., friction coefficients, friction work, efficiency) and automatically generated diagrams, characteristic values, and statistics.
- Documentation & recommendation: Results are archived in a structured manner and used to derive future substitution strategies.
Funding information
