Scientists at the University of Southampton have developed the strongest, lightest weight silica nanofibres that are 15 times stronger than steel. Their discovery could transform the aviation, marine and safety industries.
The quest has been on to find ultrahigh strength composites, which led the University’s Optoelectronics Research Centre (OCR) to set about developing light, ultrahigh strength nanowires that are not compromised by defects.
Dr Gilberto Brambilla, ORC Principal Research Fellow said: “with synthetic fibres, it is important to have high strength, achieved by production of fibre with extremely low defect rates and low weight.”
Historically, carbon nanotubes were the strongest available material, but high strengths could only be measured in very short samples, (just a few microns long) which provided little practical value.
Usually, if you increase the strength of a fibre, you have to increase both its diameter and weight, but in this study, the researchers observed a strength increase when the size of silca nanofibres was decreased. This resulted in an ultrahigh strength material that remains very lightweight.
“In fact when [silica nanofibres] become very, very small they behave in a completely different way. They stop being fragile and don’t break like glass but instead become ductile and break like plastic,” said Brambilla.
Brambilla told Laboratory News that the strength checking method for the nanofibres involves increasing the weight on the material until fracture occurs.
“The real challenge is making a single nanowire that was strong enough to stand stresses in excess of 5-10GPa keeping the density of the material low. We have done that by continuous tapering of a silica optical fibre at very low temperature,” he explained.
Nanowires may also represent a cheap, sustainable technology and the materials required to produce them: silica and oxygen are two of the most common elements in the earth’s crust. Nanofibres can also be produced by the tonne, similar to the method of production for optical fibres that power the internet.