M2A Funded EngD Studentship: Mechanisms and Inhibition of Cosmetic Corrosion of Coated Magnesium Alloys

Due to funding restrictions, this studentship is open to UK/EU candidates only.

This project provides an excellent opportunity to work with a world leading company involved in the automotive coatings market, BASF Automotive, to ascertain the effects of microstructure and processing conditions on the corrosion of advanced Magnesium alloys for automobiles.

The use of low-density materials like Aluminium or Magnesium sheet alloys is finding increased application in the automotive industry because of the need to increase fuel efficiency and to reduce CO2 emission by lowering the weight of the automotive bodies. Applications of Mg alloys in the transportation market segment is limited, however, because of difficulties in achieving the desired mechanical properties (in particular strength) and corrosion resistance, especially in the presence of chloride ions in aqueous media. The relatively poor corrosion resistance of Mg alloys originates from magnesium’s high chemical activity. Consequently, Mg alloy surfaces need to be coated to improve the corrosion resistance for most of its applications. Understanding the corrosion performance of coated Mg alloys is key for levelling their practical applications.

Compared to other construction materials used in the automotive industry e.g. steel, galvanized steel or aluminium alloy sheets, Mg alloys are subject to significantly different electrochemical corrosion mechanisms. The same holds for Mg alloys coated with organic coatings. Additionally, due to it very anodic corrosion potential, Magnesium is prone to galvanic corrosion. Electrolytic contact with more noble metals can lead to the formation of local corrosion cells, which complicates the challenge to mitigate corrosion of Mg alloys. So far, only a few comprehensive studies on the corrosion protection performance of organic coatings on Mg alloys have been published. This topic is bottlenecked as established industrial corrosion testing procedures, e.g. neutral salt spray testing, are not sufficiently correlating with corrosion processes of Mg alloys under service conditions.

This project aims to develop a better understanding of corrosion under organically coated Mg alloys (like e.g. AZ31, AZ61, AZ91D, AM50) to establish tailor made products and corrosion inhibition development of organic coatings for Mg-alloys.

Aims of the project:

1. To investigate the kinetics and mechanism of under-paint corrosion on Magnesium alloys (like e.g. AZ31, AZ61, AZ91D and/or AM50) of organically coated specimens. Ideally, the nature of the organic coatings will cover simple model coatings based on PVB or epoxy-amine chemistries to simplified ED-coatings.
2. To carry out detailed studies with coated and uncoated alloys to determine the influence of the surface preparation and paint bake process on the surface chemistry and microstructure.
3. To determine the influence of these changes on the susceptibility and its impact on the kinetics of cosmetic corrosion.
4. To evaluate the influence of galvanic coupling with a similar alloy that has seen a different history in the surface preparation or paint bake processes.
5. To study the applicability of electrochemical techniques like EIS, ACET, SKP or SVET for corrosion assessment of coated Magnesium alloys.
6. To evaluate inorganic and organic corrosion inhibitors in organic coatings and to study their mode of action to inhibit under-paint corrosion.

The combined studies will be accompanied with comprehensive in- and ex-situ electrochemical characterization by means of SKP and potentiodynamic measurements, amongst others. Surface chemical and structural characterization will be done using a world class suite of instrumentation including X-ray-photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (XRD), and field emission gun scanning electron microscopy (FEG-SEM), based in the laboratories of the Swansea University corrosion research group.

Eligibility

Candidates should hold an Engineering or Physical Sciences degree with a minimum classification level of 2:1, or a relevant Master’s level qualification. Suitable candidates would have a background in engineering, chemistry, physics or biology.

Applicants should also be naturally inquisitive, a good communicator, enjoy data analysis and designing your own experiments.

Our funders require applicants to also meet the following eligibility criteria:

You must be a UK or EU citizen (i.e. eligible for ‘home’ tuition fees at the University) and have the right to work in Wales at the end of your studies.
You must be resident in West Wales and the Valleys at the point of enrolment and throughout the duration of your studies.
You must not be financially able to participate without the award of grant funding.

Further information regarding eligibility criteria can be found at: http://www.materials-academy.co.uk/eligibility