Laser texturing is an emerging technology for generating surface functionalities on basis of optical, mechanical, or chemical properties. Taking benefit of laser sources with ultrashort (fs) pulse durations features outstanding precision of machining and negligible rims or burrs surrounding the laser-irradiation zone. Consequently, additional mechanical or chemical post-processing steps are usually not required for fs-laser surface texturing (fs-LST). This work aimed to provide a bridge between research in the field of tribology and laser materials processing. The paper reviews the current state-of-the-art in fs-LST, with a focus on the tribological performance (friction and wear) of specific self-organized surface structures (so-called ripples, grooves, and spikes) on steel and titanium alloys. On the titanium alloy, specific sickle-shaped hybrid micro-nanostructures were also observed and tribologically tested. Care is taken to identify accompanying effects affecting the materials hardness, superficial oxidation, nano- and microscale topographies, and the role of additives contained in lubricants, such as commercial engine oil.

Laser-induced periodic surface structures (LIPSS, ripples) with ~500–700 nm period were produced on titanium alloy (Ti6Al4V) surfaces upon scan processing in air by a Ti:sapphire femtosecond laser. The tribological performance of the surfaces were qualified in linear reciprocating sliding tribological tests against balls made of different materials using different oil-based lubricants. The corresponding wear tracks were characterized by optical and scanning electron microscopy and confocal profilometry. Extending our previous work, we studied the admixture of the additive 2-ethylhexyl-zinc-dithiophosphate to a base oil containing only anti-oxidants and temperature stabilizers. The presence of this additive along with the variation of the chemical composition of the counterbodies allows us to explore the synergy of the additive with the laser-oxidized nanostructures.

Solid particle erosion affects many areas, such as dust or volcanic ash in areo-engines. The development of protective materials and surface engineering is costly and time consuming. A lot of effort has been placed into the advancement of models to speed up this process. Finite element or discrete element-based models are quite successful in predicting single or multiple impacts. However, they reach their limit if an entire erosion experiment is to be simulated. Therefore, in the present work, an approach is presented which combines various aspects of the former models with probability considerations. It is used to simulate the impact of more than one billion Alumina particles onto a steel substrate. This approach permits the simulation of an entire erosion experiment on an average PC (i5-2520M CPU@2.5 GHz processor, 4 GB main memory) within about six hours. The respective predictions of wear scar and impact-mass/mass-loss curve are compared to the real experiment.

Soft polymers such as the investigated polyurethane, characterized by low Young’s moduli and prone to high shear deflection, are frequently applied in pneumatic cylinders. Their performance and lifetime without external lubrication are highly determined by the friction between seal and shaft and the wear rate. FEM simulation has established itself as a tool in seal design processes but requires input values for friction and wear depending on material, load, and velocity. This paper presents a tribological test configuration for long stroke, reciprocating movement, allowing the generation of data which meet the requirements of input parameters for FEM simulations without the geometrical influences of specific seal profiles. A numerical parameter study, performed with an FEM model, revealed the most eligible sample geometry as a flat, disc-shaped sample of the polymer glued on a stiff sample holder. At the same time, the study illustrates that the sensitivity of the contact pressure distribution to Poisson’s ratio and CoF can be minimized by the developed and verified setup. It ensures robust, reliable, and repeatable experimental results with uniform contact pressures and constant contact areas to be used in databases and FEM simulations of seals, enabling upscaling from generically shaped samples to complex seal profiles.