Investigating the electrochemistry of organic coated metal surfaces at defect sites

The project forms part of a larger partnership involving BASF Coatings, in collaboration with Swansea University and Imperial College London, where the main theme will involve furthering the understanding of corrosion-induced failure of protective organic coatings when applied to metal surfaces.

The principal focus of the project will be directed towards a fundamental understanding of the processes which occur within the confined space of a penetrative organic coating defect, down to the underlying metal. A detailed knowledge in this area is key in designing improved coating technologies which provide "self-healing" capability under situations where damage is induced, and a small area of metal becomes exposed (e.g., a stone chip in painted car bodywork).

The research will concentrate on three specific areas of interest:
(i) the development of appropriate electrochemical techniques and experimental methodologies which allow the study of dynamic changes in the corrosion behaviour of exposed metal surfaces at a penetrative organic coating effect.
(ii) the influence of the defect topography and composition of the protective organic coating, with particular emphasis on the primer layer, on the corrosion processes and kinetics of corrosion occurring on the exposed metal surface. The metal substrates to be studied will comprise cold rolled, galvanized and zinc-aluminium-magnesium alloy coated steel, while organic coatings will concentrate on simple model paint systems.
(iii) correlation of dynamic changes in the electrochemistry of the exposed metal at the defect with release of inhibitive agents stored within the protective coating, initially focusing on industry standard corrosion inhibitive pigment technologies, but extending to novel, intelligent release additives.
The investigation will be carried out using comprehensive in-situ and ex-situ electrochemical characterization by means of scanning Kelvin Probe (SKP), Scanning Vibrating electrode technique (SVET), alongside potentiodynamic and electrochemical impedance spectroscopy methods in the laboratories of the Swansea University corrosion research group. Surface chemical and structural characterization will be carried using a suite of instrumentation including X-ray-photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (XRD), and field emission gun scanning electron microscopy (FEG-SEM).

Project Tasks:
- Develop experimental methodologies to investigate the electrochemistry of exposed metal substrates at a penetrative coating defect, initially concentrating on the application of SKP to monitor changes in corrosion potential and SVET to determine time-dependent changes in anodic and cathodic currents. It is anticipated that the use of microprobe electrode technology can also be adapted to characterise metal substrate electrochemistry at a defect under external polarisation.
- A systematic study the effect of defect size, organic coating thickness and composition on dynamic changes in the corrosion behaviour of the exposed metal.
- Carry out chemical characterisation of the post-corrosion metal surface at the defect site to elucidate the phenomena responsible for the observed dynamic changes in corrosion behaviour.

The CDT will produce 50 graduates with doctoral level knowledge and research skills focussed on the development and manufacture of functional industrial coatings. Key impact areas are:

Knowledge
- The development of new products and processes to address real scientific challenges existing in industry and to transfer this knowledge into partnering companies. The CDT will enable rapid knowledge transfer between academia and industry due to the co-created projects and co-supervision.
- The creation of knowledge sharing network for partner companies created by the environment of the CDT.
- On average 2-3 publications per RE. Publications in high impact factor journals. The scientific scope of the CDT comprises a mixture of interdisciplinary areas and as such a breadth of knowledge can be generated through the CDT. Examples would include Photovoltaic coatings - Journal of Materials Chemistry A (IF 8.867) and Anti-corrosion Coatings - Corrosion Science (IF 5.245), Progress in Organic Coatings (IF 2.903)
- REs will disseminate knowledge at leading conferences e.g. Materials Research Society (MRS), Meetings of the Electrochemical Society, and through trade associations and Institutes representing the coatings sector.
- A bespoke training package on the formulation, function, use, degradation and end of life that will embed the latest research and will be available to industry partners for employees to attend as CPD and for other PGRs demonstrating added value from the CDT environment.

Wealth Creation
- Value added products and processes created through the CDT will generate benefits for Industrial partners and supply chains helping to build a productive nation.
- Employment of graduates into industry will transfer their knowledge and skills into businesses enabling innovation within these companies.
- Swansea University will support potential spin out companies where appropriate through its dedicated EU funded commercialisation project, Agor IP.

Environment and society
- Functionalised surfaces can potentially improve human health through anti-microbial surfaces for health care infrastructure and treatment of water using photocatalytic coatings.
- Functionalised energy generation coatings will contribute towards national strategies regarding clean and secure energy.
- Responsible research and innovation is an overarching theme of the CDT with materials sustainability, ethics, energy and end of life considered throughout the development of new coatings and processes. Thus, REs will be trained to approach all future problems with this mind set.
- Outreach is a critical element of the training programme (for example, a module delivered by the Ri on public engagement) and our REs will have skills that enable the dissemination of their knowledge to wide audiences thus generating interest in science and engineering and the benefits that investments can bring.

People
- Highly employable doctoral gradates with a holistic knowledge of functional coatings manufacture who can make an immediate impact in industry or academia.
- The REs will have transferable skills that are pertinent across multiple sectors.
- The CDT will develop ethically aware engineers with sustainability embed throughout their training
- The promotion of equality, diversity and inclusivity within our cohorts through CDT and University wide initiatives.
- The development of alumni networks to grow new opportunities for our CDT and provide REs with mentors.