MITC2024


KEYNOTE SPEAKERS \| INVITED SPEAKERS
*The keynote speakers' names are listed in random order.

		Prof. Dr. Tomoko Hirayama Kyoto University, Japan Title: Friction characteristics derived from microstructure of boundary lubrication layer in lubricant It is a well-known fact that the adsorption layer formed by additives reduces friction under boundary lubrication. There are two types of additive adsorption layers: physisorption type and chemisorption type. In the former, the adsorbed molecules themselves contribute to the reduction of the coefficient of friction, while in the latter, chemical reaction products with the surface, such as ‘metal soap’, contribute to it. In the recent trend towards further energy conservation in machinery, the clarification of friction reduction mechanism by adsorbed additive layers is an urgent issue, and optimization of additive design based on this is strongly required. In this study, friction tests for Langmuir-Blodgett (LB) films as model layers were conducted to elucidate the friction reduction mechanism by physisorbed additives. For the friction tests, an atomic force microscope (AFM) with a SiO₂ colloidal probe was used to accurately measure the elementary values of the friction coefficient. Initially, LB films of varying film density were prepared and their friction coefficients were measured. However, the results show that the friction coefficient cannot be organized by film density alone. Next, the friction coefficients were conducted by focusing on the phase state of the films. Then, a clear trend in the friction coefficients appeared as shown in the figure below, depending on whether the phase state of the film was liquid-condensed or liquid-expanded. Although the film densities are all between 3-4 molecules/nm², the friction coefficient tends to increase with decreasing surface pressure for the liquid-condensed film, while the friction coefficient tends to decrease further with decreasing surface pressure for the liquid-expanded film. This suggests that the physical properties of the adsorption layer governing the friction properties are ‘phase state’ and that the way in which the base oil molecules are confined within the layer has a significant effect on the friction coefficient. In addition to the above, our research group has been conducting experiments on the relationship between the microstructure of the boundary lubrication layer and friction properties in lubricant using various analysis and evaluation methods. In this presentation, the author would like to introduce some of our recent results.


		Assoc. Prof. Dr. Thomas Reddyhoff Imperial College London, United Kingdom Title: Controlling friction and wear using surface texturing One of the most direct ways to increase energy efficiency is to reduce mechanical friction through improved lubrication, since friction is responsible for a significant proportion of wasted energy in all machines. Applying texture – i.e., micro-features such as dimples or pockets – to the surface of engineering components is a way of improving lubrication that has been investigated since the 1960s. The impact of this approach can be significant. In fact, our research has shown consistently that texture-induced friction reductions of over 60% are possible. Compared to other energy saving solutions, surface texture is relatively low-cost and simple to implement. It does not require components to be redesigned and can be incorporated into existing and future technologies. Despite its simple concept and the intense attention, it has received, the effect of textured surfaces on friction has proved to be a challenging topic to understand and apply. This is because texture interacts with, and complicates, frictional processes, which themselves depend on interactions between surface and lubricant chemistry, fluid and contact mechanics that are not always well understood. This presentation will explore our recent research on the tribological behaviour of surface texture. It will cover developments in both experiments and modelling, from a fundamental to an applied point of view. These reveal the rich and varied mechanisms with which surface topography and lubricants interact and thus affect friction and wear. The critical dependence of texture behaviour on contact conditions that vary during machine operation and between components will be explained. This shows how texture performance can be optimised by intelligently adjusting either pocket geometry or lubricant composition. Future developments arising new materials, applications and techniques will also be discussed.


		Damien Khoo Yiyuan Bruker Nano Inc., United States Title: Friction and current: Innovating lubricant testing for electric vehicles The demand for new lubricants capable of withstanding the severe conditions in electric vehicle (EV) powertrains increases as electric mobility gains momentum. High starting torques, high speeds, and uncontrollable electrical currents passing through contact points create difficulties for EV lubricant testing. Conventional tribotesters are not developed for effective lubricant analysis in electrified environments. This study introduces a UMT TriboLab modular benchtop tribometer equipped with a power source and a resistance data logger to evaluate the tribological performance of various EV lubricants under electrified conditions through different sliding tests. The findings indicate that electrical current at contact interfaces significantly impacts friction, electrical contact resistance, and wear. Consequently, the electrified tribological testing methods explored in this study could potentially provide faster and more precise screening of electric/hybrid lubricants.