Abstract
In stress-augmented thermal activation, the activation energy barrier that controls the rate of atomic and molecular processes is reduced by the application of stress, with the result that the rate of these processes increases exponentially with applied stress. This concept has particular relevance to Tribology, and since its development in the early twentieth century, it has been applied to develop important models of plastic flow, sliding friction, rheology, wear, and tribochemistry. This paper reviews the development of stress-augmented thermal activation and its application to all of these areas of Tribology. The strengths and limitations of the approach are then discussed and future directions considered. From the scientific point of view, the concept of stress-augmented thermal activation is important since it enables the development of models that describe macroscale tribological performance, such as friction coefficient or tribofilm formation, in terms of the structure and behaviour of individual atoms and molecules. This both helps us understand these processes at a fundamental level and also provides tools for the informed design of lubricants and surfaces.
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Hugh SPIKES. He graduated in natural sciences from the University of Cambridge in 1968 and received his PhD degree in mechanical engineering from the University of London in 1972. He joined the staff of the Mechanical Engineering Department at Imperial College in 1978, where in 1996 he became professor and head of the Tribology Group. He is currently a senior research fellow at Imperial College. His research areas cover all aspects of liquid lubrication, from hydrodynamic to boundary, with a particular interest in the influence of lubricant molecular composition on performance. He is a recipient of the ASME Mayo D Hersey Award, STLE International Award, and the Tribology Gold Medal.
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Spikes, H. Stress-augmented thermal activation: Tribology feels the force. Friction 6, 1–31 (2018). https://doi.org/10.1007/s40544-018-0201-2
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DOI: https://doi.org/10.1007/s40544-018-0201-2
Keywords
- stress activation
- stress augmented thermal activation
- mechanochemistry
- friction
- EHD friction
- wear
- Eyring