Development and design of novel multiFUNctional PEO COATings

Project Information

FUNCOAT

Grant agreement ID: 823942

DOI

10.3030/823942

Project closed

EC signature date 1 October 2018

Start date 1 January 2019

End date 31 December 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 1 301 800,00

EU contribution

€ 1 301 800,00

Coordinated by

HELMHOLTZ-ZENTRUM HEREON GMBH
Germany

Periodic Reporting for period 2 - FUNCOAT (Development and design of novel multiFUNctional PEO COATings)

Reporting period: 2022-07-01 to 2024-12-31

Summary of the context and overall objectives of the project

The main objectives of the project are the design, development, upscaling and application of innovative PEO surface treatments to produce active multi-functional surfaces for key industries such as transportation and 3C as well as for novel environmental cleaning and antifouling/antimicrobial applications. The key technology in focus was plasma electrolytic oxidation (PEO) treatment, which was additionally functionalized by particles (including nanocontainers) and/or organic/inorganic chemical compounds. The approach was keeping in focus the internal porosity of the PEO coatings which are normally detrimental for the properties especially for the corrosion performance. Therefore, in the past and most of the time without success, it was one of the aims in PEO research to prevent or at least to reduce the porosity. However, the porosity is a result of the discharges, which are responsible for the coating formation, thus it is principally impossible to generate a perfectly dense coating without defects.
The FUNCOAT project has combined some multi-step post-treatments with an in-situ one step approach to add active corrosion protection and other functionalities. These newly developed PEO coatings were primary tested for corrosion protection and photocatalytic activity and obtained surfaces (Fig. 1) demonstrated sufficient performance. Moreover, the PEO processes were adapted and modified to be suitable for different industrial applications, such as improvement of wear performance due to addition of superhard particles (e.g. cubic BN) or lubricative additives (e.g. PTFE), considering the environmental and health regulations and offering coatings with new functionalities and better performance compared to standard PEO process at comparable costs. More details about the obtained scientific results can be found in the project related publications, as the crucial impact was given to the dissemination of the gain knowledge both between project partners/beneficiaries and broad auditorium.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The work within the project was started with the development of a power supply for the PEO treatment offering bipolar pulses, wide flexibility of processing parameters in combination with the recording of those parameters. This power supply is ready and has successfully passed the field-tests in the labs of project participants. In parallel to the development of power supply, the preliminary work on the synthesis and characterization of functional particles and containers was performed. Several inorganic nanostructured materials were prepared with the aim to introduce new and stable functionalities to PEO coatings. ‘Smart’ nanocontainers acting as host material for immobilization of active compounds were developed and prepared. The selected active compounds were corrosion inhibitors, commercial biocides and others. These materials were tested for their environmental impact and tried to be incorporated into PEO layers.
It was shown, that many functional materials are very sensitive and do not survive the plasma discharges. Briefly, the decomposition of the particles influences the PEO processing and mechanism of PEO coatings formation. From one hand, it can be considered as a negative result of the project, as original functionality of the particles can not be used in the resultant PEO layers. However, in frame of the project we have also discovered, that the decomposed particles can lead to beneficial properties of the resultant coatings. For example, it was demonstrated that the addition of LDH particles resulted in a significant increase of PEO surface and formation of foamy ceramic structure (Fig. 1e), beneficial for photocatalytic properties, but not very effective for «smart» corrosion protection [1].


[1] K. Mojsilović, M. Serdechnova, C. Blawert, M.L. Zheludkevich, S. Stojadinović, R. Vasilić, “In-situ incorporation of LDH particles during PEO processing of aluminium alloy AA2024”, Applied Surface Science, 654 (2024) 159450

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The main targeted functionalities, expected in frame of FUNCOAT project and related to transport industry, are enhanced fault tolerance and active protection against corrosive damage as well as improved tribological behavior. Moreover, to extend this typical field of applications of PEO treatments and address additional industries and aspects (e.g. 3C, environmental protection), a set of less common functionalities, such as photocatalytic, magnetic, thermo- and electro-conductivity were investigated. These functionalities were introduced in situ via incorporation of functional particles and/or molecules in a single step PEO treatment. This is challenging and goes far beyond the standard functionality introduction via post-treatments. However, some of the particles and nano-containers (e.g. layered double hydroxides (LDHs) loaded with organic corrosion inhibitors)) are very sensitive to heat and decompose in the discharges. To deal with such sensitive particles/compounds during PEO processing, specific changes in the process design and control of the energy input was designed and built in frame of the first reporting period of the project. The first design of functional particles, based on Si-shells and LDH nanocontainers, magnetic materials and photoactive species was also suggested in FUNCOAT project.
Unfortunately, the project implementation was noticeably delayed due to the COVID#19 pandemy and geopolitical situation, because of which both Belarusian partners were removed from the consortium. Following these unexpected changes, the risk mitigation actions were suggested and the necessary amendments were performed. The purpose of this amendment was to involve new partners in the consortium (replacement of partners from Belarus), increase of the duration of the project and redistribution of secondments in order to keep the original aims and objectives feasible.
Within the second reporting period a significant effort on the intercalation of pre-selected particles during the PEO processing using the newly developed power supply system was performed and understand the differences between bipolar and unipolar pulses on the incorporation of particles. A number of functionalized PEO layers in accordance with the original objectives of FUNCOAT project was obtained and the respective results were broadly presented and published. Briefly, the most effectively PEO layers were developed for corrosion protection (via LDH- and MOF-based post-treatments), for photocatalytic application (via adjustment of electrolyte composition and addition of zeolites and other particles in the bath) and wear improvement (use of superhard and lubricative additives). The lab level up-scaling of developed technology was performed and drawbacks were analyzed, discussed and minimized.

Cross-sectional morphology of PEO layers with different additives. Example of foamy ceramic layer.