New range of self-healing materials

Certain types of synthetic materials are designed to chemically repair cracks and other defects in their structure. Such materials are widely referred to as self-healing, and often have durability advantages.

The EU-funded 'Training network for self-healing materials: From concepts to market' (SHEMAT) project is investigating these materials. The nine-member consortium primarily aims to implement self-healing in various materials, and to commercialise the developments.

Additionally, SHEMAT intends to develop standardised methods for characterisation of self-healing potential. The goal is key to commercialisation, and unique to SHEMAT. The project focuses on four types of material: polymers, fibre-reinforced polymer composites, concrete and ceramics. The three-year undertaking concludes at the end of 2015.

To date, 15 young researchers have been selected for the project's career-development programme.

Work began with a workshop intended to define the assessment of self-healing materials, which is a step towards a method for characterisation.

Additionally, the team compared the economic costs of large-scale bacterial spore production under classic and new culture conditions for concrete applications. The research concluded that the novel technique, in combination with water treatment waste products, leads to a significant cost reduction.

The study also demonstrated that self-healing thermal barrier coatings (TBCs) can be realised under certain chemical conditions. Healing of crack damage in such materials occurs by oxidation at service temperatures. The TBC concept has been transferred to a new EU project for commercial exploitation.

In addition, the project has demonstrated self-healing of MAX phases with aluminium compounds, whereby selective oxidation fills damaged sites. The crack-healing process is applicable to various titanium and chromium compounds. Full quantification has been presented in one case, showing that full strength recovery and repetitive healing is possible. Manufacturing options are being considered.

To date, SHEMAT has achieved progress towards defining the chemistry of certain self-healing material applications. The results facilitate commercial application of the processes.