Advanced Materials series - Will materials which heal themselves transform maintenance?
Intrinsic self-healing materials involve the use of specialised polymers, which are intrinsically able to heal through reversible reactions and supramolecular bonding activity after an application of energy via heat, light, or other sources. Extrinsic self-healing materials, such as capsule systems and vascular systems are also common. These systems function by releasing a healing agent from reservoirs within the material, either via microcapsules for the former or interconnected tubes for the latter, which break open under stress. These agents react to the new conditions to restore the integrity of the material. Self-healing properties have been applied to materials such as concretes, metals, ceramics, and elastomers.
Self-healing building materials could increase product life cycle and reduce maintenance costs for bridges and tunnels. Applying self-healing coatings to protect metals from corrosion could reduce wear and damage at the wheel-rail interface and between other moving metal parts. Transparent, polymeric coatings could be applied to glass and paint to protect them from scratch damage, and thus increase the product life cycle of rolling stock.
Self-healing rubber could improve the longevity of rubberized moving parts or the integrity of sealants. The potential of self-healing materials repairing damage on rolling stock could lead to a reduction in energy and labour costs for maintenance, and the reduction of risk of failure due to damage will lead to safer and more reliable rolling stock.