Understanding grease. How the self-assembled microstructure controls oil retention and release
Understanding grease: how the self-assembled microstructure controls oil retention and release
Grease is a soft material consisting of oil embedded in a matrix of self-assembled fibers of amphiphilic molecules. The relative affinity of these two components is crucial for the macroscopic properties of the material – and hence also for its performance as a lubricant in bearings. If the grease releases, ‘bleeds’, too much oil, it will exhaust quickly. If bleeding is insufficient, there is not enough oil in the lubricating contact. Both effects reduce the life-time of the bearing. The objective of this project, which is supported by SKF, the Materials Innovation Institute (M2i) and Tata Steel, is to understand the separation of oil from grease and ultimately to develop a model that describes the relevant processes in a quantitative manner. To this end the micro-structure of idealized model grease materials will be visualized and characterized (e.g. using confocal microscopy techniques and Atomic Force Microscopy) and the oil separation properties will be quantified on a macroscopic scale. Oil separation will be linked to the rheology of the grease and to its (physical) chemistry.
The goal of the project is (1) to understand the relationship between the material/microstructure, the bleeding properties and film forming properties; (2) to develop a model that predicts grease bleeding under static and dynamic conditions.
The task of the PhD student is to identify and – if necessary – develop suitable techniques to characterize the microstructure and the mechanical properties of model greases. He/she will carry out the experimental measurements and process and analyze the data using standard software tools such as Matlab. Together with the supervisors, the PhD student will develop a (continuum) model to describe the oil separation, based – at least initially – on porous media flows. He/she will also interact in regular meetings with the industrial partners (primarily SKF) to ensure that knowledge and results are efficiently transferred in both directions.
The project will be carried out at the University of Twente (UT), supported by members of the Surface Technology and Tribology (STT) and the Physics of Complex Fluids (PCF) Group under the supervision of Prof. Piet Lugt (STT) and Prof. Frieder Mugele (PCF), with daily guidance by
Dr.ir. R. Bosman (STT) and Dr. D. van den Ende (PCF). For details, see the webpages of STT and PCF.
To ensure eligibility for a Dutch PhD examination candidates should have a MSc degree in physics, mechanical engineering, chemistry, or materials science. The ideal candidate has experience in quantitative atomic force microscopy, ellipsometry and rheometry. We expect a pro-active and curiosity-driven attitude, excellent command of English and good communication and presentation skills to guarantee efficient information exchange with academic and industrial partners.
Conditions of employment
The University of Twente offers a stimulating work environment in an area of applied, forefront research. When fulfilling a PhD position at the UT, you will get the status of junior scientist. You will have an employment contract for the duration of 4 years with UT employee benefits. The gross monthly salary starts with € 2174,- in the first year and increases to € 2779,- in the fourth year of your employment. Additionally, the University of Twente provides excellent facilities for professional and personal development, an 8% holiday allowance, an 8.3% end of year bonus. A high-quality training programme is part of the contract. The research should result in a PhD thesis at the end of the employment period. The position is available immediately.
Prof.dr. Frieder Mugele (PCF): +31 53 489 3094 firstname.lastname@example.org
Prof.dr.ir. P.M. Lugt (STT): +31 6 51 222474 email@example.com
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List of publications (if available)