M2A
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In-situ Mapping of Stress Corrosion Cracking Using a Scanning Electrochemical Probe

Key Information

Academic supervisor: Professor Geraint Williams

Industry supervisor: Dr Ronald Clark, C.Eng, C.Sci

Background:
Previous work has shown that a scanning vibrating electrode technique (SVET) can be used to map the types of locations on nuclear fuel cladding alloys where corrosion sites initiate upon immersion an aggressive chemical environment. To further develop our understanding this degradation process there is a need to consider the influence of stress on the cladding. In service this can arise from residual stresses (e.g., cold work, machining), and/or applied stresses (e.g., hoop stresses from swelling of spent fuel pellets). The application of tensile stress is commonly regarded as being detrimental to sustained passivity of stainless steel alloys in the presence of aggressive ions such as chloride. However, relatively little systematic work has been carried out to characterise the relationship between applied stress and localised corrosion initiation/propagation. Such an endeavour requires an approach where electrochemical studies are carried out in-situ on a specimen placed under tensile stress in a corrosive solution.

This study seeks to employ the use of a tensile strain rig, allowing specimens to be placed under load and scanned in-situ upon immersion. The facility will also allow the test sample to be polarised, enabling the influence of applied potential and stress on localised corrosion behaviour to be studied. Figure 1 shows a schematic diagram of the proposed instrumental set-up, which will combine an in-house designed and constructed SVET apparatus with a bench-top horizontal static tensile strain rig. Experiments will be conducted using notched, or “dog-bone” -type specimens prepared from flat sheet austenitic stainless steel alloy. Such preliminary research will assist in developing future SVET-SCC (Stress Corrosion Cracking) capability for further experiments using specific nuclear materials, e.g. 20Cr 25Ni Nb stainless steel.

Figure 1: Schematic diagram of in-situ SVET set-up to characterise localised corrosion behaviour of metallic specimens under tensile stress.

Project Aims:
•    Obtain SVET current density maps of immersed stainless steel specimens under strain at:
o    a range of tensile loads
o    a range of chloride concentrations
o    a range of fixed applied potentials
•    Macro photographs or optical micrographs of specimens after SVET-SCC corrosion experiment
•    Scanning electron microscopy of specific sites of interest after SVET-SCC corrosion experiment (e.g. corrosion pits, stress corrosion cracks)

Before submitting an application for the project, please see our Hints & Tips document which can be found here.

Sponsoring Company National Nuclear Laboratory (NNL)

Established in 2008, the National Nuclear Laboratory brought together the UK’s nuclear research and development capability into one organisation. Our workforce represents a combined 10,000 years of expertise in nuclear science and technology and we’re continuing to grow.

Company Website Eligibility

We welcome applications with Materials Engineering preferred, but other physical sciences accepted (Engineering, Physics, Chemistry), 2.1 or 1st class degree preferred, or equivalent relevant experience that would enable the candidate to fulfil the role.
Previous experience with some of the techniques mentioned above is desirable, as well as a basic understanding of corrosion or materials degradation phenomena.
Strong communication skills, both verbal and written. Keen to publish research and present at conference(s).
Normally, we would expect candidates to have met the University’s English Language requirements (e.g. IELTS 6.5 overall with 5.5+ in each component) by point of application.
Full eligibility can be found at https://www.materials-academy.co.uk/eligibility

Funding

Fees at Home / EU rate and Stipend £12500, both for the period of one year.
For full details on funding eligibility, please refer to the Materials and Manufacturing Academy (M2A) Website.
Due to funding restrictions, this scholarship is not open to ‘International’ candidates.

Closing Date 21 February 2021

Start Date October 2021


Apply Now

Informal enquiries about this studentship are welcome and may be directed by email to: M2A@swansea.ac.uk