The lubrication of machine elements to ensure the operational capability of equipment and thus the avoidance of maintenance costs is a central and highly relevant topic worldwide, even in the age of digitalisation and e-mobility. According to estimates by Holmberg and Erdemir, approximately 23 % of the total worldwide energy consumption is due to friction and wear. Of this, approximately 20 % is due to overcoming friction, and 3 % is due to maintenance/repair of wear-related damage. How are machine elements lubricated nowadays?

Oil and grease friction are common methods of protecting friction contacts from excessive friction and subsequent wear. Metal production and machining, e.g., for mobility applications, is one of the most important sectors of the Austrian economy, and the costs resulting from friction and wear are significant and amount to several million euros per year. Examples of this are coke chutes in coking plants in the steel production environment, where several tonnes of coke are used every day at high temperatures (approx. 850 °C) and in a reducing atmosphere, which cause severe wear to the materials used and thus require maintenance work and the associated downtimes, but also bearings in rolling stands or very energy-intensive forming processes such as the deep drawing of sheet metal for the automotive and aerospace industries. Friction plays a decisive role here for sheet metal qualities, and this naturally influences the service life of the deep-drawing tools to a great extent. Liquid lubricants are often environmentally hazardous, flammable, and have to be removed with organic solvents at the end of the deep-drawing process. Here, new lubrication concepts with auxiliary laser-structured surfaces in combination with novel 2D solid lubricants could significantly reduce energy and thus costs.

Apart from metal processing, however, there is also a great need for new tribological concepts in the transport sector. Particularly in the aviation sector of helicopters, control rod and tail rotor shaft bearings are still classically lubricated with grease. This has led to some serious accidents in the recent past, and the idea in the future is to make these relevant bearings for the manoeuvrability of rotorcraft grease-free and to apply innovative solid lubricants for this purpose.

In electromobility, high-speed bearings with speeds of up to 25,000 rpm with the aim of mass reduction, but also the increase of the on-board power supply voltage to up to 800 V, are particularly challenging in terms of material selection and material surface processing. In particular, the reduction of friction in wheel bearings and the associated durability and resource efficiency play a decisive role here.

The aim of this contribution to Task 12 within the AMT-TCP was to address novel 2D materials (e.g., MXene, graphene/graphene oxide, transition metal carbodichalcogenides (TMCCs)) and laser-based surface processes (Direct Laser Interference Patterning) that contribute significantly to friction and wear reduction and thus to durability and resource efficiency.

Austria (Task lead), Germany, China, UK, USA, Brazil

Project lead

Prof. Dr.-Ing. Carsten Gachot
Institute of Engineering Design and Product Development E307
Research Unit Tribology
Vienna University of Technology
Lehárgasse 6, 1060 Vienna
Phone: +43 (1) 58801 30763
E-Mail: carsten.gachot@tuwien.ac.at