Photo: Michael Schwarzenberger


Butterfly valves are used to control air flow in bleed air systems and for environmental control systems. A typical butterfly valve includes a housing that defines an air flow passage. A shaft is mounted in a housing and supports a butterfly disk that incorporate a sealing ring and a stiffer. An actuator rotates the shaft to selectively open or close the butterfly disk to control the air flow through the passage in the housing. In this type of configuration, leakage is generated mainly by the wear of the sealing elements. Thus, the wear rate is the main parameter to be considered, and the well understanding of the high temperature wear behaviour of the materials used in these components under extreme conditions is essential.

Nowadays, cobalt alloy like Stellite 6 is used for the manufacturing of the butterfly sealing rings. High temperature wear of sealing rings and stiffness under complex thermomechanical stresses leads to bleed valve internal leakage increase. The limitation of leakage through the correct selection of materials, the design of the sealing rings and housings, adequate manufacturing routes and the correct assembly between the stiffener and the butterfly will ensure a perfect seal avoiding possible leaks during operation, what will lead to a reduction of fuel consumption of about 1.8 kg/h for small-medium range aircraft. Furthermore, the avoidance of cobalt oxidized wear particles in the airflow will result on an improved cabin air quality.

Photo: Courtesy of Liebherr


Nickel-based alloys like NiCrSiFeB Self-Fluxing alloys exhibit excellent corrosion and are reported to be wear-resistance up to 600 oC. They also demonstrate an excellent oxidation resistance up to melting range, and satisfactory resistance to some organic acids. Nowadays, these materials are mainly used as coatings. So, the project will identify and define the critical process parameters to manufacture the Nickel based self-fluxing alloys by Centrifugal Casting (CC) and Laser Metal Deposition (LMD).


The project will go a step forward in the processing of Nickel Self-fluxing alloys by two new manufacturing routes oriented to replace Cobalt parts considering Eco Design process optimization approach based in LCA analysis for the development and future industrialization of sealing rings
of aero engine components. The manufacturing process development and the selection of the best NiCrSiFeB alloy and associated process parameters set will be supported with data analytics and validation testing, including metallurgical and mechanical characterization, tribological studies at high temperature, toxicity analysis and LCA & LCC analysis.


New manufacturing routes for Ni Based self-fluxing alloys

It will be possible to manufacture bulk parts of NiCrSiFeB alloys. Control of solidification ranges to avoid microshrinkage problems will be key in CC process, together with process modelling to reduce setting up times. Specific process conditions such as thermal gradients and fine powder stream will be combined with a melt- pool size monitoring system and a multivariate process control system in LMD process. The development of robust manufacturing study will be supported by advanced data analytics.

How to determine the best NiCrSiFeB alloy as Cobalt alloy replacement
  • Extensive tribological studies at high temperature
  • High temperature mechanical properties (hot hardness) Advanced Microstructural analysis
  • Toxicity analysis
  • LCA & LCC analysis

Firstly, the best combination of process parameters for both CC and LMD and chemical composition will be selected. Afterwards, 8 sealing rings will be manufactured, 4 by CC and 4 by LMD, including post-processing operations for endurance test. A complete characterization of the worn surfaces of the tested rings

will be carried out by electron microscopy and non-destructive testing. These results together with outcomes from toxicity analysis and LCA/LCC will define the potential substitution of current Cobalt rings by the developed alternative ones.


  • To reduce the overall manufacturing cost of sealing rings >30% for both CC and LMD process maintaining or increasing the wear resistance as compared to Stellite 6.
  • For LMD process, to reduce time- to-market from several months to one month.
  • To obtain viable solutions to replace Cobalt in future aero components.
  • Reduce EU dependence on critical raw materials like Cobalt.


  • To reduce material waste and scraps by 12% per component for CC and 25% per component for LMD.
  • To reduce CO2 emissions, perceived noise and fuel consumption due to the expected limitation of leakage and the suppression of pressure relief holes per valve leading to a reduction of fuel consumption of 1.8 kg/h for small-medium range aircraft.
  • To contribute to the development of next generation of High Performance and Energy Efficient systems, such as for new Environmental Control Systems (ECS) to be incorporated in the Ultra High By-pass Ratio (UHBR) engine of future aircraft.
  • To improve aircraft cabin air reducing the potentially contaminated bleed air.


Reduction of scrap
  • In the case of CC, the tighter cooking control by the refrigeration of the mold and the selection of adequate coatings will lead to a reduction of scrap rate due to microshrinkage of around 60% and additional material for pre-machining of 30%.
  • LMD, being an additive manufacturing technology, will allow to reduce both production time and waste generation, and thus, less energy consumption will be necessary. It is expected a reduction in material waste and scrap of >50% compared to conventional manufacturing routes like machining.
Reduction of dependence on critical raw materials

Cobalt is one of the 27 critical raw materials for the EU, being mainly used as battery chemicals (49%) and superalloys (18%). The Cobalt demand in EU is about nine times higher than the supply, so EU strongly depends on imports. Substitution of Cobalt with other more common metals will reduce EU’s demand on this critical raw material.

Reduction of potential hazadous materials

Cobalt has some hazardous properties. The wear of Cobalt alloy particles can end up in the cabin air, what supposes a potential health concern. The substitution of Cobalt by Nickel self-fluxing alloys together with the increase of the wear resistance will reduce the presence of debris in cabin air.


The work plan is divided into 7 WPs – 2cross-cutting WPs (dedicated
to Project Management and to Dissemination and Exploitation), and 5 technical WPs – with a duration of 24 months (from 1st January 2021 to 31st December 2022).

  • WP1 is dedicated to the definition of the requirements and specifications for the sealing rings, study of the self-fluxing nickel alloys to be used and definition of the test plan.
  • WP2 will address the manufacturing process study, including the obtaining of the best parameters to manufacture NiCrSiFeB alloys by both CC and LMD together with the use of advance data analytics methodologies.
  • WP3 will be focused on the metallurgical and tribological characterization of the best candidates selected in the previous WP. Wear rate evolution of the selected Ni-alloys will be compared to Stellite 6.
  • WP4 will be focused on environmental aspects. Thus, wear particles will be analysed and the toxicity of debris particles will be assessed. Additionally, the environmental impact and life cycle cost of the sealing rings obtained by CC and LMD will be obtained and compared to current product.
  • After selecting the most promising Ni-alloy solutions for both processes, WP5 will address the manufacturing of the sealing rings and their final testing.


Project launched at Kick-off meeting

15 January 2021

The project was launched during the kick-off meeting that was held on-line, due to the pandemic, on the 15th of January 2021. All partners, the topic manager LIEBHERR and the Project officer, who represented the Clean Sky Joint Undertaking, participated in the meeting.
The participants shared a common vision of the project, including the objectives, the planning and the required activities to achieve the expected results. The working plan was set up and validated.

Presentation of project results in EU congress and other events:

  • Project presentation in the LASER CONNECT 2021 event, promoted by AIMEN. October 21-22, 2021, virtually. Development of a new manufacturing route by LMD with NiCrSiFeB alloys to replace cobalt in aeronautical components. Event page:
  • International Additive Manufacturing Conference IAM22: Pereira, J.C., Zubiri, F., Aguilar, D., Taboada, M., Guillonneau, G., Rocchi, J. Development of a New Manufacturing Route by Direct Laser Metal Deposition With NiCrSiFeB Alloys to Replace Cobalt in Aeronautical Components. ASME International Additive Manufacturing Conference, 19-21  October 2022. Lisbon, Portugal.
  • Oral presentation in the scientific event: XVI Congreso Nacional de Materiales (CNMAT 2022):  Desarrollo de una nueva ruta de fabricación por deposición directa con láser LMD con aleaciones NiCrSiFeB para sustitución del Cobalto en componentes aeronáuticos. 28 June – 1 July 2022 Ciudad Real, Spain. ISBN 978-84-09-38118-0.
  • Poster presentation by ECL-LTDS in the Scientific and Academic event: 24th  International Conference Wear of Materials (WOM). 16-20 April 2023. Alberta, Canada.
  • Oral presentation in the European project SURE5.0 webinar about “How can additive manufacturing improve manufacturing process in EU SMEs”. The presentation was entitled “Advances in metal additive manufacturing: use cases” and NEMARCO use case was presented. 20 September 2023.

Press articles and Open-Access Research articles:

Final Technical Project meeting at Liebherr Aerospace Toulouse SAS

19 September 2023

The final meeting of the Clean Aviation project NEMARCO coordinated by Lortek was held on September 19th at Liebherr Aerospace Toulouse SAS facilities in France. In the final meeting, the WPs leaders shared and discussed with the topic manager the main results, conclusions and lessons learned after the execution of the technical tasks in which two new manufacturing routes were developed for the new generation of NiCrSiFeB sealing rings of the Liebherr bleed air valve systems.


After finalizing the execution of WP2 and WP5 tasks, the main progress was done on the final selection of the 2 most promising composition grades for self-fluxing nickel alloys, and the manufacturing of the tubes preforms by gravity casting (GC) and Laser Metal Deposition (LMD) processes. Finally, two sets of sealing rings prototypes were machined, grinded and tested at Liebherr up to 20 000 cycles and the leakage measured, evaluated and compared against current solutions of materials used for the sealing rings.

Other major progress was the completion in WP3 of the tribology studies at room and high temperature (up to 650 °C) for the NiCrSiFeB alloys obtained by the two new manufacturing routes proposed in NEMARCO (GC and LMD). High load tests were conducted to generate the debris particles for the preliminary toxicity analysis conducted in WP4. The wear kinetics study at variable contact temperature was completed. The main conclusions after tribological characterization and studies conducted in NiCrSiFeB alloys and Stellite 6 reference alloy were stated, determining the wear mechanics, wear response, and the mechanisms of the glaze layer formation in NiCrSiFeB alloys. A new methodology to characterize the tribological behaviour under high temperatures using a limited number of tests and samples were created by ECL-LTDS.

In WP4, preliminary analysis of wear particles toxicity study was made, observed effects are comparable between the wear particles obtained from NiCrSiFeB samples researched in the project and those from the Stellite 6 controls. An extensive LCIA study were made after finalizing WP2 and WP3 activities, and after the tubes preform manufacturing in WP5. The main findings were compiled. The LMD process is cheaper than GC manufacturing route for sealing rings prototypes obtained at lab scale. The comparative CO2 emissions between the current industrial manufacturing route (with Stellite 6 and CC process) and the proposed new manufacturing routes (GC and LMD) is biased since in NEMARCO project the measured values and recorded data has been extracted in pilot lab scale processes, not fully representative of a serial industrial production environment. According to the environmental study conducted, CO2 emissions in the best-case scenario for the LMD manufacturing route of NiCrSiFeB sealing rings are higher than GC manufacturing route developed.

After endurance tests conducted by Liebherr, the leakage measurements show the good behaviour of the developed materials in NEMARCO. The alloy obtained by LMD route seems more sensitive to wear especially on external face of the sealing rings. The materials obtained by GC and LMD exhibits some brittle defects that should be avoid working on the design and the manufacturing process that still need to be better adapted to NiCrSiFeB composition grades selected. The final results are very interesting and promising.

NEMARCO LMD tube preform manufactured with NiCrSiFeB alloy at LORTEK and final sealing ring protype machined at Liebherr Toulouse Aerospace SAS.

Electro-pneumatic bleed air system with detail of sealing rings installed in their butterfly valve (Liebherr Toulouse Aerospace SAS).


NEMARCO project is composed of 5 partners from 2 different countries (Spain and France), with complementary skills and experience, covering the whole project value chain. The partners are referent entities in their fields at European level and have collaborated together in previous projects.

LORTEK is the project coordinator. LORTEK and AZTERLAN will be focused on manufacturing, specifically the former on LMD and the later on CC, both for the process study as well as the manufacturing of the demonstration rings. CIDETEC and LTDS will deal with the metallurgical and tribological characterization, while CTME will address the toxicity assessment and the life cycle cost analysis. LORTEK will be responsible of exploitation and dissemination.

LIEBHERR is the Topic Manager and will steer the NEMARCO project included in the Systems (SYS) Programme of the Clean Sky2 Joint Undertaking initiative.

Dr. Juan Carlos Pereira
Project Coordinator – LORTEK

Legal Advice

Legal Information

In keeping with Act 34/2002 dated 11 July, on Information and e-Business Society Services, we are informing you that the internet domain,, is owned by Lortek, S. Coop. (F20759072), located in Arranomendia kalea, 4A, 20240 Ordizia (Gipuzkoa), telephone number 943882303, e-mail, and listed with the Register of Cooperatives in Euskadi, under number 2013.0.053

Lortek, S. Coop. (hereinafter “LORTEK” or “the company”) is a technological research and development centre. The website at (hereinafter, “the website”) is a website owned by LORTEK.

1. General Terms and Conditions

The user accesses this website voluntarily. Access to this website is free of charge. Browsing this website implies acceptance and knowledge of the legal notices, terms and conditions of use, and the privacy policy therein contained. Should the user not be in agreement with these terms of use and not give his consent, he/she may not make use of this website.

Access to this website, as well as the use that may be made of the information it contains, are the exclusive liability of the user. The user commits him/herself to use this in keeping with the purpose of the website.

The user may not make illicit use of the information contained in this website or perform acts that may damage or alter the information systems thereof.

The inclusion or communication of content by users that is false or inaccurate or that leads or may lead LORTEK or other users or third parties to error is prohibited. Users shall be solely liable for the damages they may cause by communicating such data.

The use of personal data belonging to third parties without their consent, as well as the use of third-party identification data with the intention of impersonating or pretending to be another person or entity is prohibited.

LORTEK exerts the maximum effort to prevent errors in the contents published on the website, reserving the authority to modify these at any time. LORTEK expressly denies any liability due to error or omission in the contents of this website for any damages that may be due to the lack of veracity, accuracy and timeliness thereof.

The website may offer links to other websites or facilitate access to these by means of a search engine lodged therein. LORTEK does not assume any liability with regard to the websites linked or the results of the searches, since it exercises no type of control over these, their content, products or the services they offer, etc. The purpose of these services is to inform the user of other sources of information. Hence, the user accesses their contents under his sole liability, subject to the terms of use applying to these websites.

In the case of links to social networks owned by the centre or by third parties, these shall be governed by the general terms of said networks.

LORTEK shall not assume liability for any consequence or damage that may arise from the use of this website or its contents, including damages in information technology and the introduction of viruses or any type of malware. LORTEK does not ensure the absence of viruses from the website or other elements uploaded by unrelated third parties that may cause alterations to users’ hardware or software systems, although it makes use all the means at its disposal to prevent this.

LORTEK reserves the right to modify or delete the design, configuration and information contained in this website at any time without prior notice and/or justification, if it so considers appropriate. LORTEK does not assume liability for the damages that such modifications may cause. It shall nevertheless use all the resources it avails of to inform users of any such modifications.

2. Intellectual and Industrial Property

The ownership rights to this website, its pages, screens, the information it contains, its appearance and design, photographs, images, products and services, brands, logos, slogans, etc., are held by LORTEK unless otherwise specified.

In no case shall access or browsing the website imply a total or partial waiver, conveyance or permit for personal use from LORTEK with regard to its intellectual and industrial property rights for the benefit of the user. The unauthorised reproduction, distribution, merchandising or transformation of these works constitutes breach of the intellectual property rights of LORTEK.

Users commit themselves not to undertake any action that may do damage to the ownership of this website. The unauthorised use of the information contained in this website as well as the damages caused to the intellectual and industrial property rights of its owners may give rise to the pursuit of applicable legal action and, should the case so warrant, the liabilities deriving from such.


These Terms and Conditions may undergo modifications whenever LORTEK considers such timely, either to adapt to legal changes or to carry out other types of improvements. Such modifications will be valid starting from their publication on this website. LORTEK shall use the means at its disposal to announce the changes made to website users.

Privacy Policy – Protection of Personal Data

4.1 Introduction

In keeping with Organic Act 03/2018 dated 05 December on the Protection of Personal Data (hereinafter the “LOPD”) and the regulations for its implementation, users are informed that the personal data they facilitate through e-mails sent over website forms, private areas or any other media lodged on this website shall be incorporated upon agreement into files owned by LORTEK (File Manager) in order to attend to the consultations and requests received, contact you, and manage the services requested, commercial relations and legitimate functions proper to its activity.

Your personal data shall be processed confidentially. LORTEK is committed to user privacy and personal data protection and uses all the resources within its power to ensure the security and privacy of interested parties. LORTEK complies with the legislation in force on Personal Data Protection, is listed with the General Register of the Spanish Data Protection Agency, and acts in accordance with the recommendations, reports, innovations and directives made available by the different national and European data protection agencies and other control authorities.

4.2 Gathering of Personal Data

LORTEK does not require you to provide personal data to access the website. However, there is a contact form, use of which requires the user to facilitate personal data. Users give their personal data freely and voluntarily. LORTEK does not request personal data in addition to that necessary for you to receive the service requested.

Users who upload any type of content on this website (data, texts, videos, sound, photos, graphs, messages or other materials) state and assure that they do so in a manner compliant with the conditions set forth herein. Users who upload the personal data of third parties state that they have the consent and permission of these for the publication thereof.

Should any of our services be intended for minors, LORTEK will request the consent of their parents or guardians to gather their personal data or, as applicable, to process their data.

Users are solely responsible for the veracity and accuracy of the data uploaded, whereby LORTEK is exonerated of any liability in this regard. The users, in any case, vouch and respond for the accuracy, validity and authenticity of the personal data facilitated and commit themselves to keep these duly updated.

NEMARCO Project participants’ data may be transmitted to the different companies forming the NEMARCO Consortium for project management purposes, always subject to compliance with the laws on personal data protection. Likewise, pictures taken at the different events organised in project execution may be published on this website.

The dispatch of information through this website necessarily entails express authorisation for the data processing described in this privacy policy and in the general website terms and conditions.

4.3 Rights of Interested Parties

You may exercise your rights of access, rectification, cancellation and opposition, as well as withdraw your consent or make any other request on this matter in writing, addressed to the File Manager, Lortek, S. Coop, in Arranomendia kalea, 4A, 20240 Ordizia (Gipuzkoa), tel. 943882303, or through the e-mail address The request must be sent with copy of proof of petitioner’s identity (National ID Card). The control authority you may address in the event you are not in agreement with the resolution of your requests, or to file a complaint, is the Agencia de Protección de Datos:

Should request be made in the capacity of legal representative, a document attesting such representation must be attached in addition to the ID card.

4.4 Security Measures

LORTEK shall process the personal data contained in its files adopting the technical and organisational measures necessary to guarantee security and prevent alteration, loss, unauthorised processing or access, account taken of the state of the art, the nature of the data stored and the risks to which these are exposed, whether originating from human activity or from the physical or natural environment, in keeping with the legislation in force that may be applicable with regard to security measures for files containing personal data, in particular, the LOPD and the regulations for its implementation. Users are nevertheless informed that computer safety measures are not foolproof and that they are not absolutely safe from possible undue illegal interferences for which LORTEK would not be liable.

4.5 Traffic Data

The IP address of the user’s device may be tracked in order to offer a better service through this website, thus enabling subsequent data processing to analyse, among other information, number of pages visited, number of visits, website visitor/user activity, and their frequency of use.

Users give their prior informed consent to IP tracking of devices during connection and website browsing, whereby it will not be necessary to ask them each time they access the website.

For the purpose already mentioned, this website could be measured and analysed by Google Analytics and/or similar tools, which may use page bookmarkers and cookies to analyse what takes place on the different pages of this website.

4.6 Validity

LORTEK reserves the right to adapt its privacy policy to legislative or jurisprudential changes as it sees fit. Should LORTEK introduce any modification, the new text shall be published on this same website, where the user will be able to know about it. In any event, relations with the users shall be governed by the rules provided for at the specific time of website access. Thus, LORTEK recommends that you visit this privacy policy every time you access the website.


Relations between LORTEK and the user shall be governed by the provisions of the regulations in force regarding applicable law and competent jurisdiction. Nevertheless, for those cases where regulations provide for the parties to submit themselves to specific jurisdiction, LORTEK and the user, expressly waiving any other jurisdiction that may apply to them, submit themselves to the Courts and Tribunals of Gipuzkoa.

LORTEK shall pursue breach of the foregoing terms and conditions as well as any undue use of the contents presented on this website, exercising every civil and criminal action that may be applicable in law.