Project coordinator @ CEST: Andreas Laskos

Project abstract:

The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact. Lightweight design is a strong lever to lower the fuel consumption and, consequently, with it the emissions of aviation. High performance composites and composite coatings are a key technology to help achieve these aims thanks to their favourable combination of mechanical properties and low weight. Moreover, renewable materials like bio-based fibres and resin systems offer potential environmental advantages. Today engineering solutions for airframes are still heavily dependent on metals (mostly aluminium and titanium alloys), due to the many favourable properties, such as high mechanical strength, easy recyclability and formability. However, a major drawback of metals is their generally low corrosion resistance, which requires frequent maintenance of components, which is time consuming and costly and raises safety concerns in the case of safety critical systems. In addition to negative economical and societal aspects, corrosion of metal systems and components for mobility causes significant impact on the environment that is reflected in overexploitation of valuable but limited raw materials. Moreover, state of the art corrosion protection systems has limited effects on corrosion protection and/or use toxic ingredients (e.g. CrVI) with adverse effects on human health and the environment.

Therefore, the aim of the SMART project is to develop a proof-of-concept (PoC) on eco-friendly, cost effective, self-healing composite coatings for corrosion protection of airframes. The proposed coating system will be based on biodegradable natural products (cellulose nanofibers and eco-friendly corrosion inhibitors)) with extend utilisation lifetime, lower energy and resource demand due to the self-healing ability, will be lighter and allow for better reuse and recyclability compared to state-of-the-art corrosion protection systems. Cellulose fibres possess low weight, low abrasive nature, are cheap and renewable and therefore excellent candidates for eco-friendly composite coatings for the aviation industry. One drawback of cellulose nanofibers for composite coatings is their hydrophilic character, which makes them incompatible with hydrophobic polymer matrices. Therefore, in the SMART project different pre-treatment procedures of the cellulose nanofibers will be tested to improve the interfacial adhesion between the fibres and the epoxy matrix. The corrosion inhibitors will be physically or chemically adsorbed on cellulose nanofibers, embedded into an epoxy resin and subsequently applied on the pre-treated aluminium alloy. The pre-treatment of the substrate is necessary in order to provide good adhesion and therefore optimal anticorrosion ability of the SMART coatings. Another important goal of the SMART project will be to understand the triggering/release mechanism of the eco-friendly corrosion inhibitor and the corrosion protection mechanism of the developed SMART coatings. Therefore In-situ electrochemical measurement techniques (e.g. Ion microprobe, Scanning Vibrating Electrode Technique and Scanning Kelvin Probe), classical electrochemical measurements and analytical techniques will be used.