Improvements in Gas Turbine Performance via Novel Plasma Spray Coatings offering Protection against Ingested Species

Lead Research Organisation: University of Cambridge
Department Name: Materials Science & Metallurgy


This project will involve extensive collaboration between three teams of researchers, two in the UK and one in India. The expertise and facilities of the three teams are highly complementary and together constitute a uniquely appropriate set of resources to tackle the challenges of the proposed programme. In addition, three industrial partners, all with highly relevant technical background and interests, will be actively engaged in the research. There will be extensive exchanges of samples and personnel between the partners, designed to disseminate technical expertise and facilitate the experimental programme. The work will concern an important area of manufacturing development, namely improvement of the performance of protective ceramic coatings in gas turbine engines (for both propulsion and power generation). In particular, the proposed research will lead to improved understanding of the mechanisms by which ingested species (such as sand, ash, salt etc) can cause degradation and debonding of these coatings, and also to evaluation of some promising counter-measures (which have not previously been investigated for this purpose). The coatings will be produced by plasma spraying, an advanced manufacturing technique used by several of the partners, with novel variants of the process also being available within the partnership. Experimental work will also encompass the use of a small jet engine to investigate the adhesion of ingested particulate on substrates within the turbine, complemented by extensive modelling studies.

Planned Impact

1) Suppliers of Coatings and Coating Technology. There are several UK-based firms involved in supply of (thick) ceramic coatings of the type used for thermal barrier function (and also abradable coatings for gas flow control). Prominent among these is Monitor Coatings, which is a partner in the proposed programme. They would clearly be well-placed to take advantage of information emerging from the project.

2) Suppliers of Gas Turbine Engines. AMT is a small, but rapidly growing, firm involved in the manufacture of small gas turbine aeroengines. The collaborative work planned with them should give valuable insights into the factors affecting adhesion of ingested particulate within aeroengines. Furthermore, outcomes of the programme will be of considerable benefit to various other firms involved in manufacture, supply and maintenance of gas turbines being used for various purposes.

3) Airlines and Air Travellers. Improved understanding of the effects involved should contribute to improved confidence concerning engine toleration limits. This confidence would also relate to issues such as inspection regimes after exposure. Reduction in current levels of uncertainty, both about CMAS effects generally and concerning specific volcanic ash emissions, should benefit airlines and users of air transport.

4) Researchers working on high temperature protection systems. Some project outcomes will be of interest to a wide range of researchers. These include work on the adhesion of hot ceramic particles following high speed impact onto substrates. There should also be improvements in the understanding of (impurity-enhanced) sintering phenomena, which are relevant to a wide range of situations.

Dissemination, Impacts and Timescales
Dissemination will be mainly via publication in the open literature and a project website. The UK TBC Network (see, an informal grouping of researchers and industrialists in the UK, will also be utilized. A workshop will be held in Cambridge, in collaboration with the Network. Close contact will be maintained throughout between UK and Indian collaborators, and with the industrial partners. Impact will partly be in the form of improved understanding of the effects of CMAS on the performance of aeroengines, particularly via effects on TBCs. This could contribute to the evolution of international agreements concerning exposure limits and guidelines for airlines flying in the vicinity of major volcanic emissions. Development of coating formulations with improved resistance to CMAS/VA-enhanced degradation would clearly have a strong impact. The timescale for such developments is probably of the order of 5 years (from the point when confidence in the background understanding has reached a suitable level).


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Description Substantial advances have been made concerning the hazards presented by ingestion of volcanic ash (VA) into (aeroengine) gas turbines, and possible protective measures. In particular, experimental and modelling work has led to improved understanding of the factors affecting the adhesion of VA on solid surfaces in turbines. These include particle size and softening characteristics, which in turn are sensitive to the composition of the VA (and the type of volcano concerned). There have also been developments in the capabilities for modelling of the transport phenomena involved.
Exploitation Route These findings are of considerable interest to several organizations, including Rolls Royce, EasyJet and DSTL, all of which are members of the PROVIDA consortium (based in the Gordon Laboratory). Plans are being made for a joint project involving these organizations.
Sectors Aerospace, Defence and Marine,Energy,Transport

Description This project has led to extensive collaboration and interest, including the creation of a major consortium comprising about 10 organisations - see It is now clear that protective measures should involve, not only monitoring of ash levels in the atmosphere, but sampling of the ash (using drones) and analysis of the particle size distribution and composition. This will allow a much higher level of confidence in making decisions about any restrictions or recommendations about flying in the vicinity of the eruption concerned.
First Year Of Impact 2015
Sector Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Transport
Impact Types Economic

Title High speed impact of ash pellets 
Description A new methodology has been developed for making large pellets of volcanic ash, heating them above their glass transition temperature, projecting them at a substrate in a gas gun (at ~100 m/s) and using high speed photography to record their in-flight and substrate impact behaviour. 
Type Of Material Improvements to research infrastructure 
Provided To Others? No  
Impact It has been shown that the source (type of volcano) and composition (particularly the content of cations other than silicon) has a strong effect on the fluidity of the pellets under these high strain rate conditions, and hence on the likelihood of particles of the ash concerned adhering to surfaces inside aeroengine turbines. 
Title Use of Dilatometry for measurement of Glass Transition Temperatures of Powders 
Description Measurement of the glass transition temperature of powders (eg volcanic ashes) is commonly carried out using TGA or DSC methods. However, this is often unsatisfactory, particularly if the glass content is relatively small. By making a powder compact, and then using dilatometry (with a small applied force on the sample), the softening that occurs on passing through the glass transition is readily detected, since it allows the compact to densify. 
Type Of Material Improvements to research infrastructure 
Year Produced 2014 
Provided To Others? Yes  
Impact There is a consortium ( working on the effect of ingestion of volcanic ashes into aeroengines, and this procedure was disseminated to all partners. Since we are studying various ashes, and they have a range of glass transition temperatures (which are important in determining whether particles adhere to surfaces in the engine), this is a useful technique 
Description PROVIDA Consortium (Rolls Royce) 
Organisation Rolls Royce Group Plc
Country United Kingdom 
Sector Private 
PI Contribution The Gordon Laboratory in Cambridge hosts the PROVIDA consortium and coordinates its activities. There are biannual meetings in Cambridge, attended by 10-15 people, and a website is provided (see the URL below).
Collaborator Contribution Rolls Royce attend the meetings and participate in various collaborative activities.
Impact This link has lead to several initiatives, including participation in a a large (invitation-only) Symposium being held in Cambridge in April 2016 (to be attended by 50 delegates). It is funded by the Helmholtz Association.
Start Year 2014
Description PROVIDA consortium (DSTL) 
Organisation Defence Science & Technology Laboratory (DSTL)
Country United Kingdom 
Sector Public 
PI Contribution The PROVIDA consortium is hosted in the Gordon Laboratory in Cambridge, where there are biannual meetings. These are attended by 10-15 people. There is also a website (see below) and various joint activities.
Collaborator Contribution DSTL attend the PROVIDA meetings and contribute actively to various collaborative activities.
Impact DSTL have encouraged participation in other consortia and project concerned with volcanic ash and a joint proposal is now being considered.
Start Year 2014
Description PROVIDA consortium (EasyJet) 
Organisation EasyJet
Country United Kingdom 
Sector Private 
PI Contribution EasyJet are part of the PROVIDA consortium, which is hosted by the Gordon Laboratory in Cambridge (see the URL below). There are biannual meetings in Cambridge, attended by 10-15 people.
Collaborator Contribution EasyJet attend these meetings, have funded trips to Iceland to collect volcanic ash samples and are arranging large scale aeroengine tests using ash provided by Cambridge.
Impact Extensive collaborative work and preparation of proposals for future funding. Other partners include Rolls Royce, DSTL, DLR and several Universities in Norway, Sweden, India and the UK.
Start Year 2014
Description Creation of PROVIDA consortium 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact The PROVIDA ("PROtection against Volcanic ash Induced Damage in Aeroengines") consortium was created as a direct result of publicity emerging from the launch of the EPSRC project. Two meetings of the consortium have already been held, with about 20 attendees in each case. About 30 individuals are involved in the consortium, representing 15 organisations (from academia, industry and government research institutes).

There has already been extensive exchange of information, results and samples for experimental study.
Year(s) Of Engagement Activity 2014