Imperial College London

ProfessorHughSpikes

Faculty of EngineeringDepartment of Mechanical Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 7063h.spikes

 
 
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Assistant

 

Mrs Chrissy Stevens +44 (0)20 7594 7064

 
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Location

 

673City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

363 results found

Delgado MA, Quinchia LA, Spikes HA, Gallegos Cet al., 2017, Suitability of ethyl cellulose as multifunctional additive for blends of vegetable oil-based lubricants, JOURNAL OF CLEANER PRODUCTION, Vol: 151, Pages: 1-9, ISSN: 0959-6526

JOURNAL ARTICLE

Ewen JP, Gattinoni C, Zhang J, Heyes DM, Spikes HA, Dini Det al., 2017, On the effect of confined fluid molecular structure on nonequilibrium phase behaviour and friction, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 19, Pages: 17883-17894, ISSN: 1463-9076

JOURNAL ARTICLE

Kontou A, Southby M, Spikes HA, 2017, Effect of steel hardness on soot wear, Wear, Vol: 390-391, Pages: 236-245, ISSN: 0043-1648

Due to incomplete combustion, high levels of soot can accumulate in engine lubricants between drain intervals. This soot can promote wear of engine parts such as timing chains and cam followers. One standard approach to reducing wear is to increase the hardness of the rubbing components used. According to the Archard wear equation, wear rate should be broadly inversely proportional to hardness. To explore this approach for controlling soot wear, wear tests have been conducted in a High Frequency Reciprocating Rig (HFRR) with HFRR steel discs of various hardness against a hard steel ball. Carbon black (soot surrogate) dispersions in model lubricants based on solutions of ZDDP and dispersant in GTL base oils have been studied. Wear volumes have been measured and wear scars and tribofilms analysed using scanning white light interferometry and SEM-EDS. It is found that, while most oils show wear that reduces with increasing hardness, for blends that contain both ZDDP and carbon black, wear rate markedly increases with disc hardness as the latter approaches the hardness of the ball. The results support the prevalence of a corrosive-abrasive wear mechanism when carbon black and ZDDP are both present in a lubricant and suggests that selection of very hard surfaces may not be a useful way to control soot.

JOURNAL ARTICLE

Marx N, Ponjavic A, Taylor RI, Spikes HAet al., 2017, Study of permanent shear thinning of VM polymer solutions, Tribology Letters, Vol: 65, ISSN: 1023-8883

The ultrashear viscometer (USV) has been adapted and employed to investigate the permanent shear thinning of polystyrene solutions in a series of phthalate ester base fluids. The permanent shear stability index based on viscosities measured at 106 s−1, PSSI(106), has been found to be a convenient way to express the magnitude of permanent shear thinning. When comparing permanent shear thinning at various shear rates in the USV, it is very important to take account of the different times of shear that are present at different shear rates. The PSSI(106) value divided by the total time of shear is then a useful way of quantifying and comparing permanent shear thinning rates. Tests using polystyrene in different viscosity base fluids have shown that this rate of permanent shear thinning depends on shear stress and not shear rate and varies linearly with polymer concentration. The rate of permanent shear thinning also varies exponentially with shear stress, suggestive of a stress-promoted polymer breakdown process. By using a small volume of test fluid in the USV and solvent extraction after a test, it has proved possible to obtain molecular weight distributions of polymer after shear using gel permeation chromatography (GPC). This indicates that the polymer breakdown process is different at low and high polymer concentrations, with molecule fragmentation at low polymer concentration but mid-chain scission at high concentration. A key feature of the USV is that, unlike other methods currently used to measure permanent shear thinning behaviour of engine oils, it subjects the test fluid to well-defined, controllable high shear conditions. Coupled with the use of GPC, this makes it possible for the first time to relate quantitatively the permanent shear thinning of engine oils to shear conditions and to polymer degradation response.

JOURNAL ARTICLE

Ponjavic A, Lemaigre T, Southby M, Spikes HAet al., 2017, Influence of NOx and Air on the Ageing Behaviour of MoDTC, TRIBOLOGY LETTERS, Vol: 65, ISSN: 1023-8883

JOURNAL ARTICLE

Shimizu Y, Spikes HA, 2017, The Influence of Aluminium–Silicon Alloy on ZDDP Tribofilm Formation on the Counter-Surface, Tribology Letters, Vol: 65, ISSN: 1023-8883

In order to reduce vehicle weight and thus improve fuel economy, aluminium (Al) alloys have been increasingly adopted as contact surfaces such as piston skirts and cylinder liners in current engines. In general, hypereutectic Al–Si alloys are used, in which hard silicon grains are embedded in a softer Al–Si single phase matrix. It is reported that after rubbing, the matrix is removed to leave silicon grains protruding from the surface. However, the response of the counter-surface by these silicon grains is rarely investigated. In this study, mini traction machine–space layer imaging (MTM–SLIM) has been used to monitor tribofilm formation in situ and investigate the evolution of both surfaces in the contact of a steel ball on an Al–Si disc lubricated by ZDDP solution. In low-load conditions, the top layer of aluminium on the Al–Si disc is removed physically to leave silicon grains protruding from the surface, while ZDDP tribofilm pads are formed mainly on the grains. On the counter-surface (steel ball), ZDDP tribofilms are formed and build up with no wear scars. In high-load conditions, deep gaps are observed to form initially round the silicon grains on the disc. During rubbing, these become shallower, while the silicon grains start to protrude. On the steel ball, ZDDP tribofilm is generated initially over the whole rubbing track, but then the tribofilm in the middle of the track is almost completely removed by rubbing against the protruding silicon grains. Wear of the underlying steel surface then ensues.

JOURNAL ARTICLE

Taylor LJ, Spikes HA, 2017, Friction-Enhancing Properties of ZDDP Antiwea Additive: Part 1-Friction and Morphology of ZDDP Reaction Films((c)), TRIBOLOGY & LUBRICATION TECHNOLOGY, Vol: 73, Pages: 54-+, ISSN: 1545-858X

JOURNAL ARTICLE

Taylor LJ, Spikes HA, 2017, Friction-Enhancing Properties of ZDDP Antiwear Additive: Part II-Influence of ZDDP Reaction Films on EHD Lubrication, TRIBOLOGY & LUBRICATION TECHNOLOGY, Vol: 73, Pages: 50-56, ISSN: 1545-858X

JOURNAL ARTICLE

Zhang J, Tan A, Spikes H, 2017, Effect of Base Oil Structure on Elastohydrodynamic Friction, TRIBOLOGY LETTERS, Vol: 65, ISSN: 1023-8883

JOURNAL ARTICLE

Costa HL, Spikes HA, 2016, Impact of ethanol on the formation of antiwear tribofilms from engine lubricants, TRIBOLOGY INTERNATIONAL, Vol: 93, Pages: 364-376, ISSN: 0301-679X

JOURNAL ARTICLE

Ewen JP, Gattinoni C, Morgan N, Spikes HA, Dini Det al., 2016, Nonequilibrium Molecular Dynamics Simulations of Organic Friction Modifiers Adsorbed on Iron Oxide Surfaces, LANGMUIR, Vol: 32, Pages: 4450-4463, ISSN: 0743-7463

JOURNAL ARTICLE

Ewen JP, Gattinoni C, Thakkar FM, Morgan N, Spikes HA, Dini Det al., 2016, Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces, TRIBOLOGY LETTERS, Vol: 63, ISSN: 1023-8883

JOURNAL ARTICLE

Ewen JP, Gattinoni C, Thakkar FM, Morgan N, Spikes HA, Dini Det al., 2016, A Comparison of Classical Force-Fields for Molecular Dynamics Simulations of Lubricants, Materials, Vol: 9, ISSN: 1996-1944

JOURNAL ARTICLE

Guegan J, Kadiric A, Gabelli A, Spikes Het al., 2016, The Relationship Between Friction and Film Thickness in EHD Point Contacts in the Presence of Longitudinal Roughness, TRIBOLOGY LETTERS, Vol: 64, ISSN: 1023-8883

JOURNAL ARTICLE

Marx N, Guegan J, Spikes HA, 2016, Elastohydrodynamic film thickness of soft EHL contacts using optical interferometry, TRIBOLOGY INTERNATIONAL, Vol: 99, Pages: 267-277, ISSN: 0301-679X

JOURNAL ARTICLE

Shimizu Y, Spikes HA, 2016, The Influence of Slide-Roll Ratio on ZDDP Tribofilm Formation, TRIBOLOGY LETTERS, Vol: 64, ISSN: 1023-8883

JOURNAL ARTICLE

Shimizu Y, Spikes HA, 2016, The Tribofilm Formation of ZDDP Under Reciprocating Pure Sliding Conditions, TRIBOLOGY LETTERS, Vol: 64, ISSN: 1023-8883

JOURNAL ARTICLE

Wang P, Zhang J, Spikes HA, Reddyhoff T, Holmes ASet al., 2016, Development of hydrodynamic micro-bearings, 16th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588

CONFERENCE PAPER

Zhang J, Spikes H, 2016, On the Mechanism of ZDDP Antiwear Film Formation, TRIBOLOGY LETTERS, Vol: 63, ISSN: 1023-8883

JOURNAL ARTICLE

Campen S, Green JH, Lamb GD, Spikes HAet al., 2015, In Situ Study of Model Organic Friction Modifiers Using Liquid Cell AFM; Saturated and Mono-unsaturated Carboxylic Acids, TRIBOLOGY LETTERS, Vol: 57, ISSN: 1023-8883

JOURNAL ARTICLE

Campen S, Green JH, Lamb GD, Spikes HAet al., 2015, In Situ Study of Model Organic Friction Modifiers Using Liquid Cell AFM: Self-Assembly of Octadecylamine, TRIBOLOGY LETTERS, Vol: 58, ISSN: 1023-8883

JOURNAL ARTICLE

Costa HL, Spikes H, 2015, Effects of Ethanol Contamination on Friction and Elastohydrodynamic Film Thickness of Engine Oils, TRIBOLOGY TRANSACTIONS, Vol: 58, Pages: 158-168, ISSN: 1040-2004

JOURNAL ARTICLE

Guegan J, Kadiric A, Spikes H, 2015, A Study of the Lubrication of EHL Point Contact in the Presence of Longitudinal Roughness, TRIBOLOGY LETTERS, Vol: 59, ISSN: 1023-8883

JOURNAL ARTICLE

Ingram M, Hamer C, Spikes H, 2015, A new scuffing test using contra-rotation, WEAR, Vol: 328, Pages: 229-240, ISSN: 0043-1648

JOURNAL ARTICLE

Leong JY, Zhang J, Sinha SK, Holmes A, Spikes H, Reddyhoff Tet al., 2015, Confining Liquids on Silicon Surfaces to Lubricate MEMS, TRIBOLOGY LETTERS, Vol: 59, ISSN: 1023-8883

JOURNAL ARTICLE

Liang H, Guo D, Reddyhoff T, Spikes H, Luo Jet al., 2015, Influence of thermal effects on elastohydrodynamic (EHD) lubrication behavior at high speeds, SCIENCE CHINA-TECHNOLOGICAL SCIENCES, Vol: 58, Pages: 551-558, ISSN: 1674-7321

JOURNAL ARTICLE

Spikes H, 2015, Basics of EHL for practical application, LUBRICATION SCIENCE, Vol: 27, Pages: 45-67, ISSN: 0954-0075

JOURNAL ARTICLE

Spikes H, 2015, Friction Modifier Additives, TRIBOLOGY LETTERS, Vol: 60, ISSN: 1023-8883

JOURNAL ARTICLE

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