Entwicklung einer innovativen Methodik zur tribologischen Prüfung von Werkstoffen unter Medieneinfluss

The progression of climate change and global warming is having an ever-increasing impact on almost all areas of industry and the economy. The reduction of global emissions through a large-scale decarbonization of the energy system and the conversion of fossil fuels to alternative energy sources play a central role in solving the energy crisis. Hydrogen as an energy carrier is considered a promising solution, although the use of hydrogen poses new challenges for the materials and machine elements used due to its corrosive and highly damaging properties of hydrogen embrittlement. This work focuses on a specific aspect of the expansion of the hydrogen infrastructure for the operation of fuel cells. Fuel cells require the use of high-purity hydrogen, which places special demands on the medium contacting bearings of high-pressure compressors. Lubricants contaminate the hydrogen gas, so the rolling bearings have to run dry and function without lubrication, which results in increased tribological stress and increased wear. The aim is to expand tribological testing techniques to include an innovative method for testing rolling contacts under the influence of a gaseous medium. Within the scope of this work, a testing machine was developed that enables the tribological testing of lubrication-free rolling contacts in a pressurized hydrogen atmosphere in a range of up to 200 bar. Specifically, the established “Three Ball on Rod” RCF test method was used as the basic test principle and implemented within an encapsulated autoclave. The torque transmission into the interior of the test cell and the drive of a cylindrical specimen is contactless via a permanent magnetic coupling. In the current project phase, the developed testing machine was used to successfully load a specimen to the point of material fatigue and to observe the formation of white etching cracks under pressurized hydrogen.