Economical Engines Due to Laser-Structured Surfaces

The more frictional heat is generated, the more fuel is consumed and the higher are the CO2 emissions. Coated piston rings seal the combustion chamber against the crankcase and generate less friction when sliding against the cylinder wall. (Source: Fh. IWS)

New diamond-like coatings and laser-structured surfaces will enable Dresden-based Fraunhofer researchers to significantly reduce CO2 emissions of engines. Cars, trucks, and buses, as well as construction machinery and gas engines, will consume less fuel and thus protect the environment. “In every engine, parts such as pistons and cylinders slide against one another. The more frictional heat is generated, the more fuel is consumed and the higher are the CO2 emissions,” explains Dr. Volker Weihnacht, who heads the research project at the Fraunhofer Institute for Material and Beam Technology IWS in Dresden. The aim is to optimally balance surface and lubricant in order to reduce friction.

“Currently, super hard, diamond-like carbon coatings already exist. We have optimized these further and added various elements to the graphite evaporated by the plasma process.” At the same time, scientists are also developing a laser microstructuring process, giving the respective surfaces a kind of shark skin effect and thus improving their sliding properties, adds Weihnacht. The interaction of the components is particularly important during development: “There is no ideal lubricant and there is no ideal surface coating and structure. It is more important to bring everything into harmony with each other and that in interaction between the various engine components,” says Dr. Volker Weihnacht, explaining the challenge and adds: “These are the levers we are turning.”

According to current scientific knowledge, the carbon layers produced at IWS under the brand name Diamor have the greatest potential for reducing friction and wear. They consist of up to 70 percent diamond bonds and are produced using the laser arc process specifically developed for these coatings.

In order to find the optimum balance between lubricant and surface, the Fraunhofer scientists work closely with engine and component manufacturers as well as material and lubricant experts. A total of twelve partners from industry and research are involved in the “Prometheus” joint research project sponsored by the German Federal Ministry of Economics and Technology. The project was officially launched at the beginning of January 2019 and will run for three years. At the end of the project, low-friction engine parts are to be prototyped and transferred to industrial series production just a few years after the end of the project. “With our developments, we are moving a major step towards lower-consumption combustion engines for a wide variety of applications,” says Dr. Volker Weihnacht, who can visualize many other applications thanks to the experience gained. It is conceivable, for example, that the solutions found could be used not only for rolling bearings but also for plain bearings such as those used in pumps. (Source: Fh. IWS)

Link: Carbon Coatings (Dr. Weihnacht Group), Fraunhofer Institute for Material and Beam Technology IWS, Dresden, Germany

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