Energy Efficiency and Tribology

Coupling in-situ tribological measurements with real time surface analysis

Supervisor(s): Prof Anne NevilleDr Abdel Dorgham, Dr Chun Wang

Project summary: Raman spectroscopy is considered one of the best surface analysis techniques to probe different surfaces at ambient conditions with less sample preparation. On the other hand, MTM-SLIM is one of the best techniques to measure the thickness and friction of ultra-thin films after different rubbing times. The project aims at coupling the capability of Raman as a surface analysis technique with MTM-SLIM as a tribofilm thickness and friction measurement technique. The project will examine different possibilities to instrument MTM rig to accommodate Raman optical extension arm. The capability of the instrumented rig will be tested using various oils, additives and steel surfaces. The effect of the ambient environment, i.e. temperature, load and relative humidity will be investigated as well. The outcome of the project will be the first instrumented MTM-SLIM-Raman for in-situ tribofilm thickness and friction of oil-lubricated systems incorporating surface analysis measurements. Furthermore, the outcome will include the first real-time spatially and temporally evaluation of the reactions of lubricant additives using Raman spectroscopy.

Tasks and expected milestones/deliverables:

Task 1 – Design MTM chamber sample holder and cover to allow the extension arm of Raman coupling.

Task 2 – In-situ MTM SLIM Raman measure friction and tribofilm thickness.

Task 3 – Use XPS to study tribo-chemistry

Task 4 – Use AFM nano force to study mechanical properties

Background of student required: The ideal candidate will be an enthusiastic and self-motivated person who meets the entry requirements qualifications for enrolment for the PhD degree at the University of Leeds. You will have a 1st or a 2:1 class degree in mechanical engineering, materials, chemistry or a related subject. Previous experience in tribology, surface adsorption and film formation, physical chemistry and experimental techniques including MTM-SLIM, Raman and FTIR are highly desirable. Good command of English language and team-working skills are essential. Applications from women seeking to progress their academic careers are highly encouraged.

Investigation of Critical concentration of friction modifiers using Raman spectroscopy for engine tribological applications

Supervisor(s): Prof Anne Neville, Dr Cayetano Espejo Conesa, Dr Chun Wang

Project summary: In situ Raman spectroscopy is used to simultaneously track the friction behaviour with time and the chemical composition of low friction tribofilm. In particular for this project, several molybdenum based additive concentrations will be tested with time using a particular set of conditions, determining the tribofilm building up as a function of additive concentration, and the concentration threshold which ensures low friction performance. Moreover, the in-situ layout will be used to determine the kinetics of friction modifying tribofilm depletion, by using less concentrated friction modifying oils, and the minimum threshold needed to maintain low friction performance. Thus, engine oil blends containing molybdenum additives can be tailored to keep the friction modifying capability for the specified service time, adjusting the composition to a minimum complying with present and future environmental regulations.

Complementary techniques will be used to full assess film mechanical and chemical properties.

Tasks and expected milestones/deliverables:

Task 1 – In-situ Raman measurement in real time to measure the friction using in situ tribometer

Task 2 – Raman ex-situ mapping

Task 3 – Nano indentor and AFM to measure the mechanical properties of the tribofilms

Task 4 – XPS and SIMS to characterize the chemical composition of the tribofilms

Background of student required: The ideal candidate will be an enthusiastic and self-motivated person who meets the entry requirements qualifications for enrolment for the PhD degree at the University of Leeds. You will have a 1st or a 2:1 class degree in mechanical engineering, materials, chemistry or a related subject. Previous experience in tribology, surface adsorption and film formation, physical chemistry and experimental techniques including Raman and FTIR are highly desirable. Good command of English language and team-working skills are essential.

Robust Optimisation of Energy Efficient Electronics Cooling

Supervisors:Prof Nikil Kapur, Prof Harvey Thompson

Project Summary: Thermal management is a key challenge for the semiconductor industry, including the need to manage high thermal densities at hotspots. Temperature control is critical for operating performance and long term reliability of electronics and the International Technology Roadmap for Semiconductors has predicted that novel liquid cooling methods are needed to manage the enormous power densities for high performance chips (>150W/cm2). Since the cooling of electronics accounts for around 0.5% of global electricity consumption there is a critical need to develop novel, energy efficient liquid cooling technologies for electronics. Heat sinks and blowers account for around 80% of the total electronic thermal management market (> $11 billion in 2016). This project will use state of the art experimental and computational methods to develop and optimise new liquid cooled heat sink solutions which are both energy efficient, meeting the industrial requirement for an energy consumption with < 1% of the total chip power consumption. The optimisation process will account for manufacturing tolerances and the optimised design(s) will be validated by manufacturing them using the School of Mechanical Engineering’s metal 3-D printers and testing their performance experimentally.

Tasks and Milestones:

Task 1 – Project orientation: literature survey on liquid cooled heat sinks, familiarisation with experimental heat sink design, Computational Fluid dynamics and heat transfer and robust design optimisation. Literature survey completed (month 6).

Task 2 – Experimental studies: initial experiments on serpentine liquid cooled heat sinks; experimental studies of benefits of channel clustering and fins. Initial validation data completed (month 12), Experiments on novel heat sink designs completed (month 24).

Task 3 – Conjugate heat transfer optimisation: develop accurate conjugate heat transfer model and validate against experiments; develop robust parametrisation of novel heat sink designs and explore design space; create meta-models of power consumption and heat transfer performance and optimise using robust optimisation methods. Validate conjugate heat transfer model (month 12); Pareto fronts and robust design optima found (months 24- 27);

Task 4 – Experimental validation of further optimisation: manufacture optimal heat sink designs on the metal 3-D printer; test performance experimentally and further explore optimisation space. Validation of optimal designs completed (month 33).

Task 5 – Write up journal papers and thesis: journal papers submitted (month 30); thesis submitted (month 36).

Background of student required: Graduate in an Engineering subject (Mechanical, Chemical), Mathematics or Physics, preferably with experience and knowledge of fluid mechanics/heat transfer.

Energy saving low-friction functional surfaces

Supervisor(s): Dr Tomasz Liskiewicz, Prof Anne Neville

Project summary: The project will be in the area of Surface Engineering and will involve development of novel thin coating for frictional applications. A major challenge in modern Surface Engineering is to produce high durability surfaces with sufficient multi-functionality for today’s technological challenges. This project will aim to understand the fundamental role of coating structure and morphology affecting durability and will be carried out in close collaboration with an industrial partner, a manufacturer of state-of-the-art surface deposition system available at Leeds University.

Tasks and expected milestones/deliverables:

Task 1 – Plasma coating technology literature review

Task 2 – Functional coating design using state-of-the-art Hauzer Flexicoat coating platform

Task 3 – Mechanical coating characterisation using a suite of micro-mechanical testing methods

Task 4 – Coating frictional performance assessment using tribometer

Background of student required: Mechanical engineering, physicist

Surface enhanced Raman spectroscopy for tribological applications

Supervisor(s): Prof Anne Neville, Dr Abdel Dorgham, Dr Chun Wang

Project summary: Raman spectroscopy can be used to obtain various useful structural fingerprints of the formed tribofilms on different surfaces at ambient conditions with less sample preparation. However, the technique has limited advantages in various tribological applications as not all the vibrational modes of the tribofilm constituents are Raman active. This mainly depends on the spectroscopic selection rules that require a change in the polarizability of the molecule. Furthermore, this technique has a large sampling depth, which makes it surface insensitive. The project aims at overcoming these issues by developing a new methodology enabling for the use of surface enhanced Raman scattering (SERS) technique in oil lubricated systems. The project will start by exploring various implementations of SERS. In the first instance, different types of nanoparticles, e.g. Au, Pt and Pd, of a wide range of sizes will be imprinted with different surface coverage on ultra—thin glass coupons or other transparent substrates, for the used laser. These coupons can then can be placed on the wear scar to examine the enhanced Raman signal after different rubbing times in oils with different additives. The outcome of the project will be a protocol for new routines enabling the currently developed in-situ rigs within IFS institute to be coupled with Raman in order to have an enhanced surface sensitive signal in real time.

Tasks and expected milestones/deliverables:

Task 1 – Using nano-particles on ultra thin glass substrate to develop SERS.

Task 2 – Use developed method to examine surface enhanced Raman signal on the wear scar.

Task 3 – Raman in-situ mapping

Task 4 – Develop protocol for in-situ Raman measurement.

Background of student required: The ideal candidate will be an enthusiastic and self-motivated person who meets the entry requirements qualifications for enrolment for the PhD degree at the University of Leeds. You will have a 1st or a 2:1 class degree in mechanical engineering, materials, chemistry or a related subject. Previous experience in tribology, surface adsorption and film formation, physical chemistry and experimental techniques including Raman and FTIR are highly desirable. Good command of English language and team-working skills are essential. Applications from women seeking to progress their academic careers are highly encouraged.

Surface-additive interaction and tribofilm formation at the nanoscale

Supervisor(s): Prof Anne Neville, Dr Abdel Dorgham, Dr Chun Wang

Project summary:  Friction and wear properties of tribological surfaces depend on the interaction between the contacting asperities and the formation of any tribofilm due to the presence of oil additives. The project seeks mainly to establish the connection between the reaction kinetics of various tribofilms and the resulting tribological properties. The project is experimental in nature and will start by investigating the additives’ adsorption on coated and uncoated steel surfaces followed by examining the decomposition of the additives and the subsequent formation of their tribofilms.  These steps will be affected by the operating conditions and type of counter surfaces. Therefore, a relationship between these variables and the tenacity and effectiveness of the formed tribofilms will be examined. The outcome of the project will be recommendations on new designs for more effective additives and best additive/surface combination. Furthermore, the results of the study will contribute to the development of better predictive friction and wear models taking into account the presence of any tribofilm and its physical and chemical properties.

Tasks and expected milestones/deliverables:

Task 1 – Generate tribofilms using AFM for lubricant with Boron containing additives.

Task 2 – Generate tribofilms using nanotribometer lubricant with Boron containing additives.

Task 3 – Use XPS and Raman to study tribo-chemistry

Task 4 – Use nano-indentation to study mechanical properties

Background of student required:  The ideal candidate will be an enthusiastic and self-motivated person who meets the entry requirements qualifications for enrolment for the PhD degree at the University of Leeds. You will have a 1st or a 2:1 class degree in mechanical engineering, materials, chemistry or a related subject. Previous experience in tribology, surface adsorption and film formation, physical chemistry and experimental techniques including AFM, XPS and Raman are highly desirable. Good command of English language and team-working skills are essential.