Plenary Talks

Zinc dialkyldithiophosphate (ZDDP) has been the principal antiwear and extreme pressure additive in crankcase engine oils for almost 80 years. Throughout the 1990s and 2000s there were considerable efforts to find an alternative that was less harmful to engine exhaust catalysts and filters. These seem to have been largely unavailing and instead limits have been placed on ZDDP’s allowed concentration and volatility. It now appears that ZDDP will continue to be used in engine oils until the demise of the crankcase engine itself.

ZDDP controls wear and scuffing by forming protective tribofilms on rubbing surfaces and over the years there has been an extraordinary volume of research to study the mechanism of formation of these films, their composition, and properties.

This talk will assess our current understanding of ZDDP, its strengths, weaknesses, and mechanisms of action. It will describe recent research that is starting to reveal the precise molecular pathway along which ZDDP molecules travel to become a tribofilm, and the way that molecular structure influences this journey. Finally, the talk will look forward to the future of ZDDP as a lubricant additive in the changing world.

Hugh Spikes graduated in Natural Sciences from the University of Cambridge in 1968 and obtained his PhD for research in Tribology from Imperial College in 1972. He is currently Emeritus Professor in the Tribology Group, Mechanical Engineering Department, Imperial College London.
Professor Spikes is a Fellow of the Royal Academy of Engineering, of IMechE and of STLE. He has been involved in research in tribology for over fifty years and has received several recognitions for his research achievements including the ASME Mayo D Hersey Award and the STLE International Award. In 2004 he was awarded the Tribology Trust Tribology Gold Medal, the highest international honour in Tribology.
Professor Spikes’ research interests span a wide range of liquid lubrication research, including hydrodynamic, elastohydrodynamic and boundary lubrication. A particular interest has been thin film lubrication and the influence of lubricant composition at a molecular level on the film-forming properties of lubricants and thus on friction and wear performance.

Friction and wear collectively consumes nearly a quarter of world’s energy output and causes more than 8 Gigatons of CO₂ emissions annually. With increasing mobility and industrial activity, adverse impacts of friction and wear on energy, environment, global economy will undoubtedly intensify. Unless we reverse this unsustainable trend, our planet may end up in a major ecological and environmental disaster. Fortunately, great strides have been made in literally vanishing friction with friction coefficients below 0.001 level. Such a remarkable progress has been achieved through many concerted efforts and worldwide collaborations centered around the creation of novel materials, surfaces, and interfaces causing little or no friction even at macro or engineering scales. In this presentation, a comprehensive overview of what makes and breaks superlubric sliding conditions and how they relate to those intrinsic and extrinsic factors that are in play from atomistic to nano- and macro-scales. In light of recent analytical, experimental and computational findings, those underlying mechanisms that are most responsible for superlubricity will also be presented. In particular, recent mechanistic studies on highly ordered 2D materials (like graphene, MoS₂, HBN, MXene, etc.) and thin solid coatings (like DLCs) as well as liquids will also be covered and their potentials for the development of large-scale mechanical systems will be discussed. Overall, these and other exciting developments are leading the way for the design and production of next generation engineering systems that can potentially vanish friction in real applications and hence save energy, improve durability, and thus protect the environment for a sustainable future.

Dr. ALI ERDEMIR is a Professor and Halliburton Chair in Engineering in the J. Mike Walker ’66 Mechanical Engineering Department of Texas A&M University, College Station, Texas, USA. In recognition of his research accomplishments, Dr. Erdemir has received numerous coveted awards (including STLE’s International Award, ASME’s Mayo D. Hersey Award, JAST’s Distinguished Tribologist Award, the University of Chicago’s Medal of Distinguished Performance, six R&D 100 Awards, two Al Sonntag Awards and an Edmond E. Bisson Award from STLE) and such honors as being elected to the US National Academy of Engineering, European Academy of Sciences and Arts, World Academy of Ceramics, The Science Academy of Turkey, and the presidency of the International Tribology Council and STLE. He is also a Fellow of AAAS, ASME, STLE, AVS, and ASM-International. He has authored/co-authored more than 300 research articles and 18 book/handbook chapters, co-edited four books, presented more than 200 invited/keynote/plenary talks, and holds 33 U.S. patents. His current research focuses on bridging scientific principles with engineering innovations towards the development of super-hard and -low-friction materials, coatings, and lubricants for a broad range of cross-cutting applications in manufacturing, transportation and other energy conversion and utilization systems.

Recently atomistic tribology simulations represented by first-principles, DF-tight-binding, potential-based, neural network potential-based, and coarse-grained molecular dynamics methods have been greatly advanced because of the development of new methodologies and the significant speed-up of computer facilities. These advancements are promoting the expansion of research targets in the tribology using atomistic simulations. For example, atomistic tribology simulations have been applied to not only calculating the friction coefficients but also revealing the tribochemical reaction mechanisms, the wear and corrosion dynamics, the generation of lubricating film, the effects of additives, atmosphere, environments, and texture, and so on. Not only the prediction of new tribomaterials and additives but also the design of surrounding atmosphere, environments, texture, and friction conditions prior to the experiments are expected and promising. In this plenary lecture, the recent advancements and applications of atomistic tribology simulations will be introduced and the future direction of the atomistic tribology simulations will be discussed.

Prof. Momoji Kubo is a director of supercomputer center in Institute for Materials Research, Tohoku University. He received Ph. D degree from Tohoku University, Japan, in 1999. In 2008 he was promoted to a full professor, Graduate School of Engineering, Tohoku University and from 2015 he is a director of supercomputer center. His works concentrate on the development of new multi-physics and multi-scale computational simulation technology based on first-principles, DF-tight-binding, potential-based, and coarse-grained molecular dynamics methods. He has been applied his originally developed simulators based on various molecular dynamics methods listed above to a wide variety of research fields such as tribology, MEMS, fuel cell, battery, catalysts, polymers, etc. He published over 400 scientific papers and received a lot of awards such as The Chemical Society of Japan Award for Creative Work. He was a leader of the MEXT supercomputer “Post-K” project from 2016 to 2020. From 2019, He has been appointed as a project leader of JST professional development consortium for computational materials scientists.

Tetrahedral amorphous carbon (ta-C) coatings are increasingly used in tribological contacts and can be found in numerous industrial applications due to their wear resistance caused by super hardness in combination with generally low friction. Fraunhofer IWS has developed a deposition technique for stable industrial coating processes for ta-C using a pulsed, laser-triggered arc discharge on graphite cathodes. The laser-arc technique can be combined with plasma filtering to reduce the density of particle-induced defects in the ta-C coatings. In addition to the further development of plasma filter technology, IWS has currently focused on the development of doped ta-C(:X) coatings by using graphite composite cathodes. In this contribution, it will be shown how doping affects the deposition behavior as well as the structure and properties of the grown ta-C:X coatings. Special emphasis is placed on the tribological properties using various engine oils and alternative, environmentally friendly lubricants.

Dr. Volker Weihnacht has been working in the field of fabrication and application of superhard amorphous carbon films for about 20 years. Since 2015 he is the division manager at Fraunhofer IWS and leads the activities on carbon coating, film characterization and tribological analysis. Fraunhofer IWS has specialized in the use of pulsed arc processes to achieve robust and stable processes for the deposition of ta-C coatings on the one hand and to improve the quality of the coatings on the other hand. With the development of the Laser-Arc technology, Dr. Weihnacht's team finally succeeded in providing an industrial deposition technology for coating parts such as automotive components and cutting tools with ta-C in series production by the millions. Dr. Weihnacht's expertise also includes the tribological characterization especially in the context of the superlubricity phenomenon, which has been observed on ta-C coatings. Numerous scientific papers and a book chapter describe the IWS work in the field of deposition and tribology of ta-C coatings.

Hydrogels are polymer networks interfiled with large amount of water. Recent remarkable progresses on the development of mechanically strong and tough hydrogel materials provide promising opportunities to apply hydrogels as artificial tissues, such as articular cartilages. For such application, understanding and controlling the tribological behavior of hydrogels in liquid medium are required. Previous studies have revealed that hydrogels could exhibits fascinating low sliding friction, as like that of cartilages. In this talk, the effects of interfacial molecular interaction, surface morphology, and rheological behavior of the liquid on the tribological behaviors of hydrogels will be discussed.

Jian Ping Gong is a distinguished professor at Hokkaido University, Japan. She obtained her bachelor's degree in electronic physics from Zhejiang University, China, and received her Master degree in polymer science from Ibaraki University, Japan. She earned her Doctor of Engineering in high Tc superconductors from Tokyo Institute of Technology. She also received her Doctor of Science in polymer sciences from Hokkaido University. She has received various scientific awards, including the Chemical Society of Japan Award in 2022, the MEXT Commendation for Science and Technology in 2019, the DSM Materials Sciences Award 2014, and The Award of the Society of Polymer Science Japan in 2006. She has been working on the development and understanding of various high-performance hydrogels and soft matters. Especially, she has developed tough double network gels, self-evolving gels, low friction gels, under water adhesive gels, biocompatible gels. Personal website: https://altair.sci.hokudai.ac.jp/g2/member1.html

Professor Chapman received his Master Degree in Governance and Public Policy (Resource Management) from the University of Queensland, and his PhD in Energy Science (Energy Economics) from Kyoto University. He is a principal investigator at the International Institute for Carbon Neutral Energy Research within Kyushu University.

Professor Chapman’s research focuses on energy systems analysis and energy economics, particularly concerned with the rapidly transitioning energy system toward carbon neutrality. Unique among his research is his modeling of the global hydrogen system, with a focus on Global, Japanese and US future scenarios. Further, his energy analysis research focuses on the culmination of a broad range of emerging technologies and the assessment of their impact on the future carbon neutral energy system. In addition to his techno-economic assessment of energy systems, he is also concerned with the social outcomes, specifically social equity or quality of life impacts.

He is involved in a number of large-scale industry collaborations, and is also a member of the Kyushu University Moonshot Project funded by NEDO, focusing on the conversion of CO₂ to useful fuels via direct air capture and utilization (DAC-U). His role in this project is life cycle analysis (LCA) and techno-economic analysis (TEA).

Professor Sofronis’ research focuses on structural materials behavior under adverse chemomechanical environments. His work addressed mechanisms underlying creep resistance of materials, dislocation defect interactions, and hydrogen-induced degradation at low and high temperatures. He has modeled hydrogen embrittlement at micro- and macro-levels, coupled with experimental observations of deformation at micro- and nano-scales. The hydrogen-induced shielding of defects to explain the mechanism of hydrogen enhanced localized plasticity is the first proposed rational explanation of hydrogen-induced fracture mediated by dislocation plasticity. He has research projects and carried out collaborative work with industry (e.g. BP, ExxonMobil), national laboratories (e.g. Sandia, Los Alamos), and government agencies (DOE, Canada Nuclear Safety Commission.) Dr. Sofronis is a fellow of the American Society of Mechanical Engineers and the Japan Society for the Promotion of Science, and received awards from the National Science Foundation, the Department of Energy, the Ford Motor Company, and the American Society of Mechanical Engineers.