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Content archived on 2024-06-18

Advanced materials for lean burn combustion tiles using laser-<br/>Additive Layer Manufacturing (L-ALM)

Final Report Summary - ASLAM (Advanced materials for lean burn combustion tiles using laser-Additive Layer Manufacturing (L-ALM))

Executive Summary:
Laser additive layer manufacturing (L-ALM) is of increasing interest as a method of manufacture for aero-engine components. The ability of the technology to manufacture complex parts in advanced nickel super-alloys makes it particularly suited to combustion components. However the operating temperature range of alloys which can currently be processed is insufficient for the future needs of the aero-engine manufacturers, taking account of environmental objectives to reduce emissions and fuel consumption. The required higher operating temperatures can potentially be met by alloys containing increased fractions of the ‘gamma prime’ phase, however these are currently very difficult or impossible to successfully process using L-ALM.

Within this project a new nickel super-alloy has been developed, which is optimised for manufacture by L-ALM. The alloy can be readily and economically processed to build defect-free parts of high complexity. Materials properties would allow use of this alloy at significantly higher operating temperatures than currently available ‘easy to process’ alloys such as In718, without the processing cost and complexity associated with existing high gamma prime alloys such as CM247.

Build process parameters and heat treatments have been developed for the alloy which optimise the key materials properties required for the envisaged end use in aero-engine combustion components. Defect free representative components have been manufactured.

Materials property data has been generated which is sufficient for use of this alloy in an engine-realistic environment (i.e. engine test rigs & test engines).

More generally we have demonstrated the principle that such alloys can be developed and optimised for this manufacturing method and that materials properties can be improved thereby. This result is of great benefit to the Participants, to the Topic Manager and to the wider European aerospace community.

Project Context and Objectives:
The objective of this project was to develop materials and processes for use in laser additive layer manufacture (L-ALM), which are capable of meeting the stated requirement for advanced, high temperature nickel super-alloys (with high levels of gamma prime forming elements) for use in novel combustion components for lean burn engine developments.

The Participants planned to review the current state of the art and determine a shortlist of potential alloys for development. In collaboration with the Topic Manager, one alloy was to be selected for development. A representative application for the selected alloy was to be defined and appropriate specifications determined for geometrical accuracy, surface finish and materials properties.

The first phase of experimental work was to develop a L-ALM process, optimised for the properties determined above. In a second phase, this 'best known' method of manufacture would be used to manufacture multiple batches of part geometries and test specimens in order to provide sufficient statistical confidence in the data to allow use of this process for the manufacture of parts for use in an engine-realistic environment.

Project Results:
The Participants, in consultation with the Topic Manager, reviewed the state of the art and selected an alloy for development within the project.

Initial work with this alloy exposed some significant processing difficulties. Work with this alloy was therefore discontinued and five further alloys were selected for empirical screening based on ease of processing and micro-structural analysis. One of these five alloys was subsequently selected as the target alloy for development.

The composition of the target alloy was refined and the powder particle size distribution re-specified with the aim of optimising the material for L-ALM. A batch of powder was then procured to this specification.

Using initial exposure parameters derived in the screening trials, heat treatments were developed to optimise for the required mechanical properties (UTS, proof stress and ductility).

Following this, a full optimisation of exposure parameters was performed. The resulting combination of optimal exposure parameters and heat treatments thus defined the ‘Best Known Process’ for the alloy. A number of defect-free representative parts were successfully manufactured using this best known process.

In the second phase of the project, the best known process was used to build a large number of test specimens in order to build a statistically significant dataset of the following materials properties: tensile, fracture toughness, creep, high cycle fatigue, notched low cycle fatigue and strain controlled fatigue.

Thus at the end of Reporting Period 2, the project has successfully completed all technical milestones and deliverables have been achieved.

A new nickel super-alloy has been developed, which is optimised for manufacture by L-ALM. The alloy can be readily and economically processed to build defect-free parts of high complexity. Materials properties would allow use of this alloy at significantly higher operating temperatures than currently available ‘easy to process’ alloys such as In718, without the processing cost and complexity associated with existing high gamma prime alloys such as CM247.

Build process parameters and heat treatments have been developed for the alloy in order to optimise key materials properties required for the envisaged end use.

Materials property data has been generated which is sufficient for use of this alloy in an engine-realistic environment.

More generally the project has demonstrated the principle that such alloys can be developed and optimised for this manufacturing method and that materials properties can be improved thereby. This result is of great benefit to the Participants and to the Topic Manager.

Potential Impact:
Impact - Clean Sky
“The greening of Aeronautics and Air Transport calls for a quantum leap in performance through a consistent, coherent and holistic approach focusing on the integration of advanced technologies and validation of results in a multidisciplinary approach leading to full-scale ground and flight demonstrators.”

Clean Sky sets out to achieve this quantum leap and is made up of 6 Integrated Technology Demonstrators, one of which is SAGE: “Sustainable And Green Engines- will design and build five engine demonstrators to integrate technologies for... high efficiency, low NOx and low weight cores and novel configurations...”

This project addresses a Call within SAGE and seeks to enable the commercial application of additive manufacturing of lean-burn combustion chamber liner tiles.

More broadly, it enables the application of this technology to complex 3D aero-thermal geometries (for both combustion and turbine applications) for static use (liners, swirlers, nozzle guide vanes, seal hangers, acoustic dampers etc.) in aero and land gas turbines and turbochargers.

For example, Additive Manufacturing enables effusion cooling holes to be placed as required by aero-thermal design (rather than limited by the capability of laser/EDM hole drilling). The resultant improved cooling reduces cooling airflow requirement leading to improved combustion and emissions.

Impact- Topic Manager
The project will enable the Topic Manager to use laser-ALM to manufacture demonstration engine combustion parts at a cost and in a time-frame that would otherwise not be possible.

Impact – University of Cambridge
The project fits well to other research activities on modelling nickel alloys to predict materials properties.

This project will allow Cambridge to correlate mechanical properties with observed microstructure arising from laser-ALM processing and heat treatments. This, in turn, will allow refinement of the models on which the computational alloy design tools are based and provide an improved capability for the design of new alloys to meet specific property targets.

Impact - Materials Solutions Limited
This project will enable and assist a materials development program, generating IP/know-how valuable to all aero engine makers. This financially supports Materials Solutions Limited, enabling more R&D work to be done quicker, and helps Materials Solutions remain relevant to high value-add industries, particularly aero-engine makers.

The project will also enhance the prestige of Materials Solutions Limited, creating a ‘halo’ effect and making it easier to gain future non-grant assisted work from high value-add manufacturers- both within the EU and outside.

Materials Solutions Limited generates its revenues by supplying Capability Acquisition services and fully manufactured parts for rig and engine-test at early stage Manufacturing Capability Readiness Levels. There are no direct competitors- no other R&D company can provide parts approved for this use. No other parts supplier has the in-house process development capabilities.

Materials Solutions has demonstrated its competence and ‘open’ nature, providing World Class knowledge-based services on normal commercial terms to all customers since foundation in 2006. Materials Solutions provides services and parts to aero-engine makers and their component suppliers in Germany, France & Spain as well as the UK and outside the EU: Switzerland, Turkey, Japan, Canada and the USA.

Impact - EU Community
Knowledge based jobs in the EU are created directly by this project and indirectly through:
a) the use of the process developed in this project
b) the new business generated at Materials Solutions (and its supply chain) supplying parts made by this new process on a commercial basis.

In addition to the direct impact on the Participants, Topic Manager and the European aerospace industry, a commercial process for high performance high temperature nickel super-alloys is of use for turbochargers - benefit to other industry sectors including:
• Land based IC/turbine CHP/electrical power generation
• Performance vehicles, e.g. Formula 1 racing’s development of turbocharged V6 engines
• Small displacement engines (IC/turbine) for electric vehicle range-extender applications and
• Conventional gasoline/diesel low emissions engines.
Turbocharging dramatically improves efficiency and reduces fuel consumption and emissions. This improves life quality and employment opportunities in the EU.

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