Current PhD Projects

Fuel-Delivered Friction Modifiers and Their Impact on Friction and Wear

ZDDPShell technical stakeholder(s): Joe Russo

Imperial supervisor(s): Professor Hugh Spikes

PhD student: Joanna Dawczyk

Overview & Objectives: Zinc dialkyldithiophosphates (ZDDPs) have been used as anti-wear additives for over 70 years. They are considered as the most efficient anti-wear additives. The tribofilm generated by the ZDDP is characterized by high boundary friction and it is known that organic friction modifiers can reduce this friction. Since both types of additives are employed together it is necessary to understand both the mechanism of the tribofilm formation and the mutual interaction between these additives. The scope of this PhD project is to study the interaction between the anti-wear film (generated by various types of ZDDP additives) and friction modifiers through the use of a range of lab analytical techniques including:

  • Mini Traction Machine (MTM)
  • Spacer Layer Imaging Method (SLIM)
  • Atomic Force Microscopy (AFM)
  • Focus Ion Beam Microscopy (FIB) followed by Ion Beam Erosion
  • Scanning Auger Microscopy (SAM) followed by Ion Beam Erosion
  • Scanning Electron Microscopy (SEM) followed by Ion Beam Erosion
  • C13 Nuclear Magnetic Resonance (NMR) to determine the structure of Zinc/friction modifier complex

Start date: March 2014

Fuel-Lubricant Interactions in the Combustion Chamber

Viscosity mapShell technical stakeholder(s): Dr Neal Morgan, Dr Renate Utiz

Imperial supervisor(s): Dr Janet WongProfessor Yannis HardalupasProfessor Alex Taylor

PhD student: Jon Dench

Overview & Objectives: The primary aim of this PhD is to develop a method to implement fluorescence spectroscopy, to a gasoline direct injection engine (GDI), to study the composition of the fuel and lubrication mixture in moving ring-pack area. This technique provides an excellent opportunity to determine not only the chemical properties of this mixture but possibly also its temperature and viscosity. In addition, the measurement of the liquid mixture film thickness is possible. Access will be made to the liner using optical fibres in a metal engine, thus ensuring typical engine operating conditions are achieved. Measurements with the fluorescence technique may be complimented with visualisation of the fuel spray in order to understand the physical mechanisms that determine the fuel-lubricant mixture composition on the liner.

Start date: September 2014

Mechanochemical Behaviour of ZDDP

ZDDP

Shell technical stakeholder(s): Dr Neal Morgan

Imperial supervisor(s): Professor Hugh Spikes

PhD student: Dr Jie Zhang (Jason)

Overview & Objectives: 

It has recently been shown that tribofilm formation by the widely-used antiwear additive zinc dialkyl dithiophosphate (ZDDP) is driven by the applied shear stress present in rubbing contacts rather than by the energy dissipated in these contacts.  This means that ZDDP reaction results from the stretching and breaking of molecular bonds under stress, i.e. mechanochemistry; an insight that enables relationships between molecular structure and reactivity to be developed.  This project studies the impact of applied shear stress on ZDDP film formation under both full film and boundary lubrication conditions to support the principle that ZDDP reaction is controlled by mechanochemistry.

Start date: March 2017

Modelling Lubricant and Lubricant Additive Behaviour using Molecular Dynamics Simulations

MD simulationShell technical stakeholder(s): Dr Neal Morgan, Dr Foram Thakkar

Imperial supervisor(s): Professor Daniele Dini, Professor David Heyes,      Professor Hugh Spikes

PhD student: James Ewen

Overview & Objectives: The aim of this project is to utilise molecular dynamics simulations to investigate the friction and flow behaviour of a range of lubricant and additve molecules. Modelling frameworks will be developed which can predict performance of a lubricant with sufficient accuracy to; screen many possible lubricant formulations and, once promising candidates are identified, obviate the need for expensive physical testing. Ultimately, the computer simulation techniques developed could be used to accelerate future lubricant development; yielding more varied, effective, formulations. 

Start date: September 2014

Modelling the Dynamics of Foaming & Antifoaming

BubbleShell technical stakeholder(s): Dr Neal Morgan

Imperial supervisor(s): Professor Daniele DiniProfessor Berent van Wachem

PhD student: Li Shen

Overview & Objectives: Foam dynamics can be summarised into four distinct stages, its formation, drainage, coarsening and eventual rupture. The aim of this project is to understand:

  • The time-dependent dynamics of the foam structure subject to non-linear liquid drainage, rupture and the consequent structure rearrangement using multiphase numerical simulations
  • The physical mechanisms involved in the formation of a large 3-dimensional foam structure due to rising bubbles (this comes from the industrial problem of foaming in lubricants)
  • The coarsening phase of the foam structure exhibiting local fractal behaviour and macroscopic polyhedral packing (Weaire-Phelan structure) using both kinetic and topological models possibly leading to new theories and/or visualisations.

Start date: September 2014

Negating the Effects of Soot on the Wear Properties of Engine Oil

Shell technical stakeholder(s): Mark Southby, Sergio de RooyWear

Imperial supervisor(s):  Professor Hugh Spikes

PhD student:  Artemis Kontou

Overview & Objectives: Soot accumulation in diesel engine oils and more recently in gasoline engine oils can increase the rate of wear in certain engine components. As such this represents an important issue for vehicle manufacturers and lubricant companies to tackle but there are many conflicting theories and mechanisms suggested as to why soot increases the wear rate and how different additive combinations reduce it. The main aim of this PhD project is to study the influence of anti-wear additives and dispersants on soot-induced wear.

Start date: March 2014

The Effect of Shear Stress on Lubricant Behaviour

Shell technical stakeholder(s): Dr Neal Morgan
Image

Imperial supervisor(s): Dr Janet WongProfessor Hugh Spikes

PhD student: Stephen Jeffreys

Overview & Objectives: 

The aim of the project is to investigate the effect of shear stress on lubricant behaviour, particularly in high-pressure high-shear environments such as those found in elastohydrodynamic (EHD) contacts. Here it is critical to gain an understanding of the rheological properties at a molecular level, considering the local structure of the lubricant. Given the severity of operating conditions lubricants can reveal unusual phenomena where the Newtonian assumption may be inadequate. An inaccurate description of the flow limits our understanding of lubricant rheology which affects the ability to theorize novel ways of controlling friction. This impacts the overall goal to manipulate the tribological performance of engineering systems and improve efficiency.

Start date: September 2016