About the Project
Background
Offshore structures are subjected to harsh environments. The combined effect of the Sun’s UV radiation, seawater and fluctuating temperatures make the splash and tidal zone the most challenging environment to long term survival. A common method of mitigating corrosion of offshore structures is to use cathodic protection. This method, however, is ineffective in the splash and tidal zone due to the lack of a continuous electrolyte (seawater) layer between the structure and the anode at all times. Although one may use a dielectric or sacrificial coating on the surface of an offshore structure to reduce anode consumption, the use of protective coatings has become indispensable in the splash and tidal zone.
Protective coatings which rely entirely on their barrier properties offer little or no protection once breached. As damage is likely in the splash and tidal zone these coating systems need expensive inspection and maintenance regime to ensure long-term protection of offshore structures. Thus, protective coating systems which can self-heal when damaged can provide a cost-effective engineering solution to corrosion and related problems.
Project Outline
The project will look at advanced electrochemical methods to characterise novel coating systems likely to self-heal when damaged. The preliminary work at the University will investigate the conversion of commercially available marine paints to novel, self-healing systems via addition of suitable encapsulated healing agents and catalysts. During the time period between coating damage and the completion of the healing reaction, the substrate metal will be exposed to seawater, so the use of a thermally sprayed sacrificial layer will also be investigated. TWI has several thermal spray systems and these will be used to achieve thermal spray coatings (TSC). The use of combined paint and TSC allows for further novel development of composite coating systems. For example, the paint could contain the liquid self-healing polymer capsules, but the catalyst could be contained in the porous TSC. This would neatly side step one of the current problems with self-healing in that the catalyst is often reactive to the polymer system and becomes deactivated.
In the proposed composite coating system the self-healing reaction would occur at the metallic surface where it has been exposed, and protection is required. A commercial paint system will be chosen based in its track record and will be further modified by additions of suitable matrix bonded fillers to promote an elastic response to impact. The damage tolerance of such coating systems will be assessed by artificially inducing damage followed by monitoring the recovery of impedance over time by using techniques to measure dielectric response as a function of applied frequency. Fundamental electrochemical characterisation techniques such as electrical impedance spectroscopy, linear polarisation resistance and zero resistance ammetry etc. will be used as appropriate to assess long-term performance.
About the Industrial Sponsor
The Lloyd’s Register Foundation funds the advancement of engineer-related education and research and supports work that enhances safety of life at sea, on land and in the air, because life matters. Lloyd’s Register Foundation is partly funded by the profits of their trading arm Lloyd’s Register Group Limited, a global engineering, technical and business services organisation.
About NSIRC
NSIRC is a state-of-the-art postgraduate engineering facility established and managed by structural integrity specialist TWI, working closely with, top UK and International Universities and a number of leading industrial partners. NSIRC aims to deliver cutting edge research and highly qualified personnel to its key industrial partners.
About the University
The University of Leicester is one of the UK’s leading universities, committed to international excellence through the creation of world changing research and high quality, inspirational teaching.
Leicester is ranked in the top 2% of universities in the world by the QS World University Rankings and THE World University Rankings. In 2013 Leicester was the highest climbing UK university in the THE World Rankings, moving up 35 places to 161st in the table.
Candidate Requirements
Candidates should have a relevant degree at 2.1 minimum, or an equivalent overseas degree in Chemistry, Materials or Engineering. Candidates with suitable work experience in coatings and corrosion, and experimental skills are particularly welcome to apply. Overseas applicants should also submit IELTS results (minimum 6.5) if applicable.
Funding Notes
This project is funded by Lloyds Register Foundation, TWI and academic partners. The studentship will provide successful Home/EU students with a stipend of £16k/year and will cover the cost of tuition fees. Overseas applicants are welcome to apply, with total funding capped at £24k/year.
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