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The paper aims to investigate the possibilities to control friction in lubricated systems by surface patterning, making use of a multi-scale approach. Surface patterns inside the tribological contact zone tend to directly reduce friction, whereas surface patterns located in the close proximity of the contact area can improve the tribological performance by avoiding lubricant starvation and migration. Finally, optimized surface patterns were identified by preliminary laboratory tests and transferred to a journal bearing, thus testing them under more realistic conditions.

Surface patterns on a large scale (depth > 10 µm) were fabricated by micro- and roller-coining, whereas surface patterns on a small scale (depth < 2 µm) were produced by direct laser interference patterning. The combination of both techniques resulted in multi-scale surface patterns. Tribologically beneficial surface patterns (verified in ball-on-disk laboratory tests) were transferred onto a journal bearing’s shaft and tested on a special test-rig. To characterize the lubricant spreading behavior, a new test-rig was designed, which allowed for the study of the lubricant’s motion on patterned surfaces under the influence of a precisely controlled temperature gradient.

All tested patterns accounted for a pronounced friction reduction and/or an increase in oil film lifetime. The results from the preliminary laboratory tests matched well, with results from the journal bearing test-rig, both tests showing a maximum friction reduction by a factor of 3-4. Numerical investigations, as well as experiments, have shown the possibility to actively guide lubricant over patterned surfaces. Smaller periodicities, as well as greater structural depths and widths, led to a more pronounced anisotropic spreading and/or greater spreading velocities. Multi-scale surfaces demonstrated the strongest effects regarding the lubricant’s spreading behavior.

Friction, as well as lubricant migration, can be successfully controlled by using micro-coined, laser-patterned and/or multi-scale surfaces. To the best of the authors’ knowledge, the study demonstrates for the first time the unique possibility to transfer results obtained in laboratory tests to a real machine component.

The purpose of this study is to investigate the influence of hemispherical structures fabricated by hot micro-coining on the resulting wear performance. Hemispherical structures with different area densities (20 and 30 per cent), depths (50 and 100 µm) and diameters (100 and 200 µm) were fabricated by hot micro-coining on stainless steel samples.

The wear performance of these samples was studied using a ball-on-disk tribometer in rotational sliding mode using a normal load of 30 N and a fixed sliding velocity of 2 cm/s. Two different poly-(alpha)-olefin (PAO) oils without any additive having a kinematic viscosity of 4 and 40 cSt, were used to study the influence of the oil viscosity on the wear behavior.

Concerning the polished reference, an enlarged wear volume with an increase in the cycle number and the oil viscosity was observed. In the case of the micro-coined surfaces, all samples demonstrate a pronounced reduction in the wear volume (up to a factor of 100 for PAO 40) compared to the polished reference irrespective of the oil viscosity used.

This study details new research work studying the wear behavior of hot micro-coined surfaces.

This paper aims to present a comprehensive perspective on how tribology and sustainability are related and intertwined and are linked to CO₂ emissions. This paper emphasizes on how tribological aspects affect everybody’s life and how tribological research and progress can improve energy efficiency, sustainability and quality of life.

Based upon available data and predictions for the next 50 years, the potential of tribological research and development is addressed.

The effects of tribological design can significantly increase energy savings and reduce CO₂ emissions. Taking advantage of tribological technologies and applying them to current infrastructure would have the largest energy savings coming from the transportation and power generation at 25% and 20%, respectively. Implementing these technologies can also cut down global CO₂ emissions by about 1,460 megatons of CO₂ per year in the immediate future and 3,140 megatons of CO₂ per year in the long term. The extraction and processing of resources inevitably generates CO₂. Doubling the lifetime of machine components and the use of circular economy reduces the material footprint with associated reductions in CO₂.

This perspective summarizes concisely the interrelation of tribology and sustainability with CO₂.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2020-0356/

Tribological research is complex and multidisciplinary, with many parameters to consider. As traditional experimentation is time-consuming and expensive due to the complexity of tribological systems, researchers tend to use quantitative and qualitative analysis to monitor critical parameters and material characterization to explain observed dependencies. In this regard, numerical modeling and simulation offers a cost-effective alternative to physical experimentation but must be validated with limited testing. This paper aims to highlight advances in numerical modeling as they relate to the field of tribology.

This study performed an in-depth literature review for the field of modeling and simulation as it relates to tribology. The authors initially looked at the application of foundational studies (e.g. Stribeck) to understand the gaps in the current knowledge set. The authors then evaluated a number of modern developments related to contact mechanics, surface roughness, tribofilm formation and fluid-film layers. In particular, it looked at key fields driving tribology models including nanoparticle research and prosthetics. The study then sought out to understand the future trends in this research field.

The field of tribology, numerical modeling has shown to be a powerful tool, which is both time- and cost-effective when compared to standard bench testing. The characterization of tribological systems of interest fundamentally stems from the lubrication regimes designated in the Stribeck curve. The prediction of tribofilm formation, film thickness variation, fluid properties, asperity contact and surface deformation as well as the continuously changing interactions between such parameters is an essential challenge for proper modeling.

This paper highlights the major numerical modeling achievements in various disciplines and discusses their efficacy, assumptions and limitations in tribology research.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0076/

This paper aims at analyzing the potential of new materials in magnesium-ion batteries (MIBs) with a particular focus on options for electrodes and electrolyte solutions while also carefully considering the barriers to their entry in this application for MIBs, with a particular focus on the material options for electrodes and electrolyte solutions.

Potential materials for MIBs were examined for sustainability, safety and efficiency to develop the sustainable and well-working MIBs.

For anode materials, the use of Mg-bismuth alloys has shown promise, whereas Chevrel phases or layered molybdenum disulfide have potential as cathode materials. Potential electrolytes range from traditional materials to the development of tailored solid-state and liquid-based options.

This study considers the growing need for Mg-based ion batteries, as well as the need for suitable electrode and electrolyte materials and analyzes suitable options.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0081/