Fri, 23 April, 2021
Topic title: Extreme high-speed laser application (EHLA) coatings
- Sponsorship and industrial supervision from TWI Ltd, Sheffield Hallam University and MERI
- Funding opportunities for UK, EU and Worldwide applicants
- Doctor of Philosophy awarded by Sheffield Hallam University
Background to this PhD project...
Protecting components against wear and corrosion has no trivial solution, with standard coating processes, such as hard chrome plating or thermal spraying having their drawbacks in terms of health and environmental concerns, coating quality or process efficiency.
LMD could be an attractive alternative, offering high integrity coating potential with significant material performance benefits over conventional processes with which it competes. LMD is already used in a limited number of cases, however its principal drawbacks are its slow coverage rate and the relatively high heat that has to be used, which can be an issue in some crack-sensitive materials.
What the project proposes...
To develop a fundamental understanding for TWI of a completely new LMD technology, using a recently developed extreme high-speed laser (EHLA) nozzle design. This understanding will start from 15 years of existing LMD processing expertise at TWI, and apply the experience gained to a number of relevant industrial needs.
The EHLA nozzle is capable of applying coatings up to in 300 µm thickness, and can also work at traverse speeds of up to 100 m/min. This represents an entirely new capability, and takes LMD from coverage rates of ~10-40 cm2/min to rates possibly up to 250 cm2/min. This is achieved by introducing the powder stream into the line of the laser beam, causing it to melt prior to reaching the melt pool, thus reducing the laser energy input into the substrate component, which in turn reduces dilution.
Image of Extreme high-speed laser application (EHLA). Photo: TWI Ltd
Research proposal...
TWI has recently acquired the UK’s first dedicated EHLA system. The PhD will focus on experimental research with this new and exciting system.
A number of different coating materials could be examined by this PhD, but as a first application, nickel-chromium based alloys would be targeted, these representing an important coating family for exploitation using EHLA. However, in all cases, there is a significant gap in the understanding of the effects of processing parameters, powder composition and powder particle size distribution on the maximum speed of deposition that can be achieved, and the quality of the deposited material (dilution, HAZ, porosity, surface quality and material properties) that results. PhD work in this area can help to develop validated and robust EHLA process parameter set(s) for these alloys for industrial application (e.g. stem coatings in turbine shafts).
This PhD will be aligned with a 4 year Future Leaders Fellowship programme (starting 2021) and a 3-year core research programme (started in January 2020). For this programme of work there will a number of industrial mentors to steer applications and materials.
Research project objectives include:
- A developed fundamental understanding of the EHLA process and the relationships between process inputs and process outputs.
- A developed knowhow in thin-coating capability to state-of-the-art level relevant to industrial applications.
- Strengthened expertise in LMD, with a UK-unique new offering in the form of an EHLA system.
- Application driven benchmarking of EHLA coatings against end-use quality and performance requirements, with reference to competing manufacturing methods.
Approach overview
The PhD student will lead the fundamental developments of TWI’s understanding in this novel coating technique through work across four areas;
- A literature review
- Carrying out iterative series of processing trials, to develop a number of application-specific deposition parameter sets for different materials
- Relating the qualities and properties of the coatings deposited, through detailed characterisation and testing of selected results of the EHLA trials
- Manufacturing of example demonstrator components, through which the developed EHLA process can also be benchmarked against competing processes
Tell me a little about Sheffield Hallam University...
The University has long been recognised for it's progressive approach with an emphasis on real-world application of research, focusing on safety, economic and challenges facing society. One of the largest in the UK, Sheffield Hallam comprises of over 30'000 students and more than 4000 members of staff. In 2020, the university was awarded 'University of the year for teaching quality' by The Times and The Sunday Times, as well as Winner of the The Guardian University Awards for Student Experience. Both awarding bodies are considered amongs the most respected in the UK. The Sheffield Hallam has also been awarded five stars in the QS International Rating System.
What is the Materials and Engineering Research Institute...?
Materials and Engineering Research Institute, also known as MERI, is a dynamic interdisciplinary research institute within Sheffield Hallam University, dedicated to addressing industrial problems through the application of fundamental science and engineering.
More information about MERI
Who are TWI...?
TWI is highly regarded research and technology organisation with headquarters in Cambridge, UK, and facilities around the world including, South East Asia, China, Australia, Central Asia, India and the Middle East. They are membership organisation, with members including Rolls-Royce, Ford, BAE Systems, EDF Energy, Jaguar Land Rover, BMW, bp, Saudi Aramco, ADNOC and many more.
As a founding partner of NSIRC, TWI run the management and day-to-day activities of NSIRC and their students, and has over 800 staff offering academic, industrial and support expertise across a range of technologies.
A to Z of TWI technical expertise and technologies
Entry requirement and subject areas for this PhD degree...
PhD candidates for this full-time studentship should have a relevant degree at 2.1 minimum in the subject of:
- Additive manufacturing
- Material science
- Mechanical engineering
- Chemistry
- or an equivalent relevant subject
Overseas degree in (academic and industry requirements) Overseas applicants should also submit IELTS results (minimum 6.5) if applicable.
To find out more or book a free consultation about this PhD position, send us an email at enquiries@nsirc.co.uk.
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