Corrosion Performance and Lacquerability of Passivated Low Tin Coatings

Key Information

Academic supervisor: Dr Natalie Wint, Dr Eifion Jewel
Industrial supervisor: Dr James Edy, Jordan Whiteside

Background:

Steel offers an economical and sustainable option for packaging and is used in numerous applications including food, beverage, and aerosol containers. Electroplated tin and chromium has been used for the corrosion protection of steel packaging for over 60 years and offers an effective system. However, with hexavalent chromium being a major component of the electrolyte for tinplate passivation and Electrolytic Chromium Coated Steel (ECCS), the requirements for REACH compliance place many constraints on manufacturers of steel packaging material.

ECCS consists of a chromium coating just 20nm (50mg.m-2) thick and as well as having good corrosion resistance also offers an excellent surface for the adhesion of organic lacquers that are used for additional protection and aesthetics. ECCS is also very economical due to the thin nano-chromium coating. Although trivalent chromium replacements for ECCS are currently in the process of commercialisation there are still strategic questions into other methods of providing suitable corrosion resistance and adequate lacquering of tin mill products as a replacement for ECCS.   The increasing cost of tin and the fact that the lowest coating weight is ~1.0g.m-2 mean a direct swap to tinplate is currently uneconomical.

This project will investigate the use of low tin coatings ( <1.0g.m-2), incorporating a Chromium Free Passivation Alternative (CFPA) treatment,  as an alternative to ECCS without the high capital expenditure required for the construction of a new trivalent chromium coating production lines.   The coating will need to provide corrosion resistance, as well as providing a suitable surface on which to apply an organic lacquer overcoat.


Project Aims:

The aim of this research project will be:

  • To investigate the corrosion and lacquerability of low tin coating chrome free tinplate (CFPA).
  • To compare the corrosion performance of free tin CFPA with conventional tinplate that is used in conjunction with a hexavalent chromium pre-treatment, as well as with ECCS.
  •  To ascertain the levels to which tin coating weight can be reduced without reducing product performance.  

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

Sponsoring Company: Tata Steel UK

Eligibility

We welcome applications from candidates with Chemistry, Physics, or Engineering disciplines. 2.1 or 1st class degree preferred, or equivalent relevant experience that would enable the candidate to fulfil the role.

Full eligibility can be found at https://www.materials-academy.co.uk/eligibility

Funding

Fees at Home / EU rate, and Stipend £20,000 per annum, for each of the four years.
For full details on funding eligibility, please refer to the Materials and Manufacturing Academy (M2A) Website (Student Eligibility | M2A).
Due to funding restrictions, this scholarship is not open to ‘International’ candidates.

Closing Date: 16th July 2021

Start Date: October 2021

Applications and informal enquiries about this studentship should be directed by email to: M2A@swansea.ac.uk

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