The Fraunhofer Institute for Material and Beam Technology IWS Dresden is working together with industry and research partners on virtually frictionless engines and transmissions.
As part of the joint projects "Prometheus" and "Chephren", the researchers want to significantly improve the energy and ecological balance of cars and other machines through improved super-hard carbon coatings.
Prometheus tech for lowerCO2 emissions from combustion engines
The project "Friction optimization of engines through the use of triboactive high-performance carbon and iron-based coatings and lubricants" (Prometheus) builds on the carbon coating technology of the Fraunhofer IWS. The already low-friction Diamor coatings in the engine are additionally doped with foreign atoms such as molybdenum or boron. For this purpose, the previous pure graphite electrodes are replaced by new composite electrodes during vacuum arc evaporation. In the motor, the doping materials then chemically bond with certain lubricant molecules and create ultra-lubricating interfaces during operation. Compared to current solutions, they should halve friction in the engine.
Chephren: On the way to a frictionless machine
The still young joint project for the "Chemical-Physical Reduction of Friction Energy (Chephren)" aims to achieve genuine "super-lubrication". To this end, the partners want to use better lubricants and, above all, significantly improve the quality of the carbon coatings. In future, these layers should be free of defects and unevenness without the need for post-polishing steps. This will be achieved by using newly developed plasma filters to "deflect" the carbon particles produced during arc evaporation so that only the ions reach the surface to be coated.
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Ultrasonic lubrication and superlubrication
Ultrasonic lubrication" can halve friction losses in combustion engines compared to the current state of the art.
The coefficient of friction is then between 0.01 and 0.05. This corresponds roughly to the friction of completely smooth steel sliding on ice.
However, experts only speak of "super-friction" when the coefficient of friction falls below 0.01.
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Laser-ArcTM and Diamor
Extremely hard carbon-based "Diamor" coatings play a key role on the way to "superlubrication". The machine operator places the components in vacuum chambers of Laser-ArcTM systems that work with vacuum arcs. A laser ignites a plasma of hot ions and electrons at graphite electrodes. Electrical and magnetic fields direct this fine cloud of charged carbon particles onto the component. A thin layer of tetrahedral amorphous carbon, abbreviated ta-C, a few micrometers thick, then forms on the surface of the component. These layers are very hard and, after mechanical polishing, also very smooth.
