Most machines contain components with loaded solid surfaces that rub together. The interaction of such surfaces produces friction and results in mechanical damage. Thus, tribological phenomena play a decisive role in diverse systems. For many years, researchers have sought to alleviate these problems and to understand their origin. In this context, the reduction of friction and wear is very often the primary focus. Nevertheless, there are many applications such as brake systems and clutches in which a controlled increase in friction is desired. applications e.g. micro electromechanical systems (MEMS), positioning devices and bearings. There are many potential solutions to manipulate friction by modifying the surface materials e.g. changing the design of the rubbing elements, using hard coatings like TiC, TiB2 or (TiAl)N, multilayer coatings such as WC/DLC/WS2, lubricants e.g. oils, greases, soft metals (In, Au or Sn) or DLC films and finally by texturing the mating surfaces. In particular, the rapidly growing field of surface texturing has attracted a lot of attention in the last decades and has proven to be an effective means of improving tribological properties.

Laser surface texturing (LST) proved to be a very promising candidate because laser is a fast and environmental friendly tool offering short processing times. Moreover, by a proper variation of the laser wavelength (from UV to IR laser light), the beam polarisation (linear-, circular- or elliptic-polarisation), the pulse duration (ranging from femto- to nanoseconds or even continuous mode) and finally by adjusting the energy density, different materials (e.g. metals, ceramics and polymers) can be processed. There are manifold applications of laser surface texturing under dry and lubricated sliding conditions. Our research in this still rapidly growing field focuses on the fabrication on precise and advanced texture geometries with a holistic approach covering the texture optimization, modelling of texture effects and the influence of the texturing method on the materials microstructure besides topographical features.

Microscopic image of a laser-treated surface with 4 and 100 micrometer resolution

© Forschungsgruppe Tribologie