Green Tribology

Lead Research Organisation: University of Southampton
Department Name: Faculty of Engineering & the Environment

Abstract

Tribology is the essential underpinning science of lubrication, friction and wear and therefore is paramount to the efficient operation of numerous mechanical systems such as engines, gearboxes, human joint implants, manufacturing, sustainable energy and ship performance just to name a few. The specific field of green or environment-friendly tribology emphasizes the green or clean technology aspects of wear, friction and lubrication of interacting surfaces in relative motion in numerous mechanical systems. The interaction of these surfaces is of importance for energy or environmental sustainability and has impact upon today's environment. This includes tribological technology that mimics living nature and thus is expected to be environment-friendly, the control of friction and wear that is of importance for energy conservation and conversion (thus emissions and carbon footprint), enhanced manufacturing techniques such as chemical mechanical polishing, environmental aspects of lubrication and surface modification techniques as well as tribological aspects of green applications such as the wind-power and tidal turbines. The area of green tribology will therefore directly affect the economy by reducing waste and extending equipment life, improve the quality of life and will help reduce the carbon footprint of many mechanical systems. It will also help address the need for increased resource responsibility and lower the health risks by creation of legislation compliant surfaces and coatings to replace potential hazardous coatings currently being used.

The proposal is from a group that is very able to manage the highly innovative and challenging research into the new area of Green Tribology. The group will be able to join various disciplines together that are essential to establishing a multidisciplinary team, namely chemistry, tribology, mechanical engineering, surface science, material science and manufacturing. The grant would focus on developing the right environment for innovative research and new directions to be studied and therefore designs for managing a flexible research portfolio are presented. The research would cover modelling and experimental approaches. The team will build world-leading and disruptive research solutions and demonstrators in green tribo-materials and natural product chemistry, tribo-metrology, tribo-electrochemistry, tribo-smart coatings, tribo-sensing to develop green tribology solutions.

Planned Impact

The outcomes of this Green Tribology Platform grant will directly benefit a broad range of consumer products associated with automotive (sustainability and durability of vehicles), renewable energy production (marine- and land-based), household appliances, industrial machines and plants, to the healthcare sector by providing green tribology solutions, more energy efficient systems and innovative coatings to allow improved international competiveness, product robustness and market distinction. The grant will facilitate new and improved environmentally friendly products and manufacturing processes, as well as allow the UK to have greater competitiveness in the micro-electromechanical systems (MEMS) and tiny-technologies markets. These products and potential spin-out companies formed from the research outcomes will aid wealth creation. The UK industrial community would also by being able to rapidly take a distinctive technological advantage from having a specialised multidisciplinary green tribological research group and facilities able to generate and model unique systems with greater functionality and performance while offering compliance with increasingly strict legislation and demands for sustainability. Thus, the new Green tribology team will accelerate improvements in tribological performances leading to longer life cycles for mechanical systems and accordingly reduced consumption of materials. At the environmental level, it should be expected that there will be reduced energy consumption and the replacement of toxic lubricants by biodegradable and renewable organic substitutes. The Green Tribology research group would also act as a catalyst to simulate research across the UK. The immediate benefit will be to the partner companies of the Green Tribology team and the wider nCATS industrial partners and collaborators listed here: Wartsila, International Paint, Castrol, BAE Systems Surface Ships, Airbus, Chevron Oronite, Daido Industrial Bearings Europe, DePuy International, DSTL, ESR Technology, FAG Aerospace, GE Aviation, Hardide, Lloyd's Register, Mantis Deposition, Micro Materials, Oerilikon Balzers Coating, Phoenix Tribology, Plasma Quest, Rolls-Royce, Rotork Controls, Schlumberger, Score Europe, Shell, TaiCaan Technologies, Teer Coatings, Tribotex, TWI, Vestas, Philips Oral Healthcare, Diamond Hard Surfaces, GKN Aerospace, Smith & Nephew, Kittiwake, TecVac, Element 6, Diamond Detectors Ltd., Transvac and Omega Completions. Every attempt will be made to broaden the impact across the UK throughout the grant period by various methods of disseminating research output and holding workshops and open days. UK industry will benefit by having access to a highly skilled research group and fully equipped laboratories, as well as specialised computational models to allow product design concepts and sub-system performance testing. The likely timeframe for true impact of this research is likely to be up to 10 years due to the novelty involved but immediate improvements in energy efficiency of many tribological systems are anticipated by the end of the grant period.

Publications

10 25 50
 
Description Train bearings. During the research on train bearings (that is still ongoing) we found out that rail axle bearings fail by rolling contact fatigue. So far it seems that initiation of the failure is due to electrical damage or to a white layer that forms because the bearings in service are overloaded. We are not sure yet which one of these two damages is the initiation cause and how they are related. More bearings removed from service will be analysed to clarify this.

The vibration data measure by the sensor produced by Perpetuum Ltd have been analysed for many good and damaged bearings and we have noticed that the vibrations are affected by:
1) the speed of the train,
2) the loading during turning
3) the conditions of the track,
4) the conditions of the bearing and
5) the conditions of the wheel.
Therefore a correlation between bearing damage and vibration is not straight forward as all these parameter play an effect on it. A study has been carried out eliminating all these variables. The understanding of the failure mode of the bearings could be used by other researchers and by the bearing manufacturer to improve the bearing properties in relation to their environment.

Disc drag rotors: A novel benchtop drag measurement technique using an analytical rheometer to measure the torque on minidiscs (4cm diameter) has been developed. The method is highly reproducible and is able to distinguish between discs fouled in the sea at 2-week intervals. The disc coefficient of momentum was found to correlate with actual surface roughness measured by optical profilometry. This was led to collaboration with a world-leading marine paint manufacturer (Akzo Nobel/International Paint) who will fund further method development. A torque rotor for large (28cm diameter) discs rig has also been constructed and commissioned in collaboration with a KTS placement and a student project. The rotational velocity necessary to cause detachment of macro-fouling organisms from heavily fouled commercial antifouling coatings has been measured.

Acrylic bone cements: A student project demonstrated that it may be possible to improve the properties of the continuous polymer phase of bone cement by changing acrylic monomer composition. An additive was identified that influences the dispersion of radiopaque pigments in the cement, which could affect wear of artificial hip replacements. Variations in polymer molecular weight have been observed in cements retrieved from surgical revisions.

Wind turbines: Experience on blade leading edge erosion testing was gained through EU Project Windtrust. We have quantified the rate of erosion due to high velocity sand impact on wind turbine blade leading edge protective coatings, and demonstrated that pre-existing erosion caused by sand impact influences subsequent raindrop erosion. We have found that erosion behaviour may change significantly at sub-zero temperatures. These findings will be used by a leading manufacturer of wind turbine blades to improve their product development of leading edge coatings. Approached by Siemens for potential collaborations on blade leading edge testing.

Dental cleaning: PhD project on tooth cleaning technology is underway in conjunction with Glaxo Smith Kline and the UK National Physical Laboratory. Tooth brushes and dental abrasive pigments have been characterised. An existing tribometer has been modified to accept toothbrush heads for abrading tooth surfaces, and a new multi-station rig has been designed.

Marine antifouling: An EU sponsored project (Foul-X-Spel) has resulted in a new way to make low or zero toxicity antifouling paints. No improvement in fouling resistance was observed during the timeframe of the project, but this coating has shown other interesting effects that could result in significant fuel saving for operating ships. These coatings could reduce drag on ships resulting in fuel savings and reduced greenhouse gas emissions. A PhD study has started which is using a hyperspectral camera to measure slime and marine fouling on ships' hulls when they are in dry dock. This special type of digital camera can measure the colour spectrum of light at individual pixels in the image. The colour is characteristic of particular types of fouling (such as seaweeds) and with the help of a computer the digital images can be used to rapidly calculate the extent of different fouling growths on the hull. This work is being carried out in conjunction with a major marine coatings manufacturer.

A self funded PhD study into lowering friction for lubricated contacts using arrays of laser texturing has shown repeatable benefits of up to 18% lower friction using dimples larger than the line hertzian contact size. By using anisotropic dimple designs differences in directional friction were seen using a reciprocating lubricated line contact.

A further PhD study looking at modelling and predicting degradation mechanisms of hardmetals used by downhole drilling equipment under abrasion has been developed and validated using classic crack patterns from the literature. Work to incorporate corrosion into the model is underway. This model will be helpful to inform the best microstructure that resist abrasion and thus can increase drilling equipment life.

A further PhD study into cavitation erosion-corrosion damage rates and mechanisms of marine propulsion alloys (i.e. Cast Nickel aluminium bronze) has shown that selective phase attack of Pre exposed samples can have a large influence on the loss rates. Synergistic effects between mechanical and electrochemical processes have also been quantified.
Exploitation Route Feasible research will be used to fuel longer term research funds
Sectors Aerospace, Defence and Marine,Energy,Environment,Pharmaceuticals and Medical Biotechnology,Transport

 
Description Green Tribology demonstrators funded through project have been successfully used to teach the principals of tribology to a range of students from school children to degree-level. The areas progressed during and enabled beyond the grant period are detailed below but cover smarter asset management, antifouling and low drag surfaces, erosion of wind turbine blades, dental cleaning and novel bone cement development. Condition monitoring of train bearings: Perpetuum Ltd (david.vincent@perpetuum.com) is the number1 producer of on-board real-time condition-monitoring-sensors for the rail environment. Thousands of sensors are fitted on trains belonging to Southeastern and other operators world-wide. Bearings with high vibrations are removed from service avoiding catastrophic failures. For the first time, the failure mode found in rail-axle-bearings has been described in detail and related to vibration signature. This industrial collaboration started in 2012 and follow-on funding was secured from Perpetuum (£109K), EPSRC IAA (£87k) and Innovate UK (£395k-Project-No:104508) to continue this research (9years). A further £1.15M (FEC) has been recently awarded by Innovate UK (Project-No:104243) to research the feasibility to monitor train-axles. Perpetuum has also fully funded a bearing rig that will give the opportunity to better understand the bearing failure in the train environment and it could also be employed as a demonstrator for technologies in different fields (e.g. wind turbines, marine turbines and tanks).' This has led a new project 'Integrated Intelligent Bearing Systems (I2BS) for UHPE Ground Demo', sponsored by the EU Clean Sky2 programme (Grant Agreement No.717174), 2016 - 2021for smart bearings development for aeroengines. Marine antifouling (1): surface test development using disc drag rotors: A novel benchtop drag measurement technique has been developed using an analytical rheometer. This method is being used to assess the effectiveness of marine antifouling coatings against the growth of micro-organisms or "slime". Slime causes drag on moving ships, which leads to great wastage of fuel and increases in greenhouse gas emissions. Previous methods of measuring drag have required large, complex and expensive equipment. Commercial marine paint companies can use the developed method to gain insights that will guide their future product development activities, and one manufacturer is sponsoring further research. We have fully met our objectives in developing this method. In future, computer modelling will let us compare the measured drag to the results of real ship trials. Marine antifouling (2): Follow-on funding by the EU FP7 project Foul-X-Spel has resulted in trials of a new low toxicity antifouling coating produced by a novel route in which organic biocides have been chemically linked to polymeric paint binders. No improvement in antifouling properties was observed, but the novel coatings may contribute to reducing drag on ships in service. This could give reduced fuel consumption and lower emissions of greenhouse gases. The platform grant also strengthened our links to DSTL and Akzo Nobel and subsequent PhD funding as well as now being an active member of the BBSRC funded National Biofilms Innovation Centre at Southampton. Low Drag Superhydrophobic Surface: Superhydrophobic surfaces can significantly reduce skin friction drag by supporting a layer of gas on the surface. Work undr the green tribology grant has focused on developing methods and materials to fabricate large are low drag superhydrophobic surfaces at low cost. An initial cost analysis of low drag surfaces was undertaken which considered what the minimum coating cost and running costs would have to be less than cost savings in fuel. This analysis showed that if a drag reduction of 20% could be achieved (this is a lower estimate) and a coating cost of < $100 per metre squared and running power of < 100 Watts per metre are obtained then a cost saving of ~12% could be expected. The dewetting performance of the surfaces were observed and showed good performance in stationary water. Some improvements to the geometry were identified which could allow more robust performance. This work has led to follow-on funding from BAESystems as an EPSRC iCASE PhD studentship (2019-2023) for achieving low drag of submerged hulls. Acrylic bone cements: Acrylic plastic cements are used in most hip replacement operations to fix the artificial ball joint into the thigh bone. These cements have changed little since they were introduced in the 1960s. We have shown that small changes in the composition of cements can change their physical properties, and are exploring whether any improvements can be made without compromising their good properties. We have shown that we can influence the structure of hardened bone cement by changing the formulation variables, and a student project measured the effect of acrylic monomer changes on cement hardness. An additive has been identified that can influence the dispersion of radiopaque pigments, which could change the wear of artificial hip replacements. Variations in polymer molecular weight have been observed in cements recovered from failed hip joints. Wind turbines: Wind turbine blades are now so long that the tips move at such high speed that grit and even rain drops in the air can cause damage when the moving blade strikes them. Special polyurethane coatings are applied to the edge of the blades to protect against this. We have used a custom type of sand-blasting rig to measure the effect of particles hitting the blades at different angles. An x-ray CT scanner was used to see damage developing beneath the surface of the coatings before it was visible to the naked eye. We have also shown that the properties of protective coatings change at low temperatures. Continued engagement with LM Windpower and FP7 Windtrust programme funding. Dental cleaning: Toothbrushes and abrasive dental particles have been characterised and the key variables likely to affect the efficiency of tooth cleaning have been identified and these are being explored experimentally. Funding from GSK for two PhD studentships followed (£120k) and is continuing to fund research at nCATS and we are jointly preparing a KTP application with us currently. Modelling of drill string tribology: PhD student jointly supervised with Prof Higgs at CMU (now Rice University USA) project to model abrasive wear of tungsten carbide drill string parts and enabled collaboration with NPL. Secondment Impact: The grant spawned two EPSRC KTS one to NPL and one for the PI to visit Rolls-Royce and work with Ric Parker (Head of R&T) and Dave Rickerby (RR Fellow for Surface Engineering) to develop a strategy for tribology within RR and be a member for their Materials and Mechanical Systems Advisory Board and author two reports for them. Also winning a KTP with Kittiwake on lubricating oil quality / condition monitoring. People aspects: The grant helped retained key researchers in tribology and enable 10 PhDs and maintained our industrial profile by expanding our company collaborations with BAESystems, Akzo Nobel and Parker Kittiwake.
First Year Of Impact 2014
Sector Aerospace, Defence and Marine,Education,Energy,Healthcare,Pharmaceuticals and Medical Biotechnology,Transport
Impact Types Cultural,Societal,Economic

 
Description AkzoNobel Phase 1
Amount £20,700 (GBP)
Organisation AkzoNobel 
Department AkzoNobel UK
Sector Private
Country United Kingdom
Start 01/2015 
End 07/2015
 
Description AkzoNobel Phase 2
Amount £36,144 (GBP)
Organisation AkzoNobel 
Department AkzoNobel UK
Sector Private
Country United Kingdom
Start 08/2015 
End 06/2016
 
Description Drill-string friction
Amount £250,000 (GBP)
Organisation Schumberger 
Sector Private
Country United Kingdom
Start  
 
Description EPSRC IAA
Amount £36,500 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 07/2016 
End 03/2017
 
Description EPSRC IAA / Pertetuum
Amount £50,000 (GBP)
Organisation Perpetuum 
Sector Private
Country United Kingdom
Start 09/2013 
End 04/2015
 
Description Feasibility study into non-contact ultrasonic cleaning to address the Adhesion Riddle
Amount £100,313 (GBP)
Organisation Rail Safety and Standards Board 
Sector Public
Country United Kingdom
Start 11/2014 
End 08/2015
 
Description Industrial Funding
Amount £25,000 (GBP)
Organisation Perpetuum 
Sector Private
Country United Kingdom
Start 04/2017 
End 09/2017
 
Description Industrial Funding
Amount £45,000 (GBP)
Organisation Perpetuum 
Sector Private
Country United Kingdom
Start 05/2015 
End 06/2016
 
Description Innovate UK Grant: The Management and use of Biofilms
Amount £100,000 (GBP)
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 04/2016 
End 03/2017
 
Description KTS with Perpetuum
Amount £62,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 09/2013 
End 04/2015
 
Description Kts with Perpetuum phase 2
Amount £45,000 (GBP)
Organisation Perpetuum 
Sector Private
Country United Kingdom
Start 05/2015 
End 06/2016
 
Description MADES
Amount € 275,783 (EUR)
Organisation European Metrology Research Program (EMRP) 
Sector Public
Country United Kingdom
Start 11/2012 
End 07/2014
 
Description Research Stimulus Fund
Amount £17,803 (GBP)
Organisation Institute of Life Sciences 
Sector Academic/University
Country India
Start 11/2016 
End 06/2017
 
Description Windthrust
Amount € 499,947 (EUR)
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start  
 
Description Oral presentation at ICEFA VI in July 2014 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Dissemination of research - Observing early stage rail axle bearing damage
Year(s) Of Engagement Activity 2014
 
Description Oral presentation at ICEFA VII July 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Dissemination of research - Mapping of Rolling Contact Fatigue in Rail Axel Bearings
Year(s) Of Engagement Activity 2016
 
Description Oral presentation at ICMCF 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Dissemination of research - Drag Dependence on Fouling
Year(s) Of Engagement Activity 2016
 
Description Oral presentation at ICMCF 2014 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Dissemination of research - Drag Dependence on Fouling
Year(s) Of Engagement Activity 2014
 
Description Oral presentation at the Stephenson conference April 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Dissemination of research - Real-time on-board condition monitoring of train axle bearings
Year(s) Of Engagement Activity 2015