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20 June 2017

Newly-developed Ceramic Microfibre Sponges Offer Flexible Insulation Option

If you were tasked with creating a new form of highly flexible material for use in the insulation industry, ceramic likely wouldn’t be your first choice. However, a new research project conducted by the Brown and Tsinghua Universities has found a way of doing exactly that, creating flexible ceramic ‘sponges’ with potential applications ranging from insulation to water purification.

Img: Gao/Li/Wu/Brown University/Tsinghua University
Huajian Gao, a professor in Brown University's School of Engineering and a corresponding author of the research, said of the project, “The basic science question we tried to answer is how can we make a material that's highly deformable but resistant to high temperature. This paper demonstrates that we can do that by tangling ceramic nanofibers into a sponge, and the method we use for doing it is inexpensive and scalable to make these in large quantities.”

So, given the typical nature of ceramic as a material, how exactly does it manage to deform rather than shatter? While items such as a ceramic bowl will likely shatter into a thousand pieces if dropped from a height due to the way in which the cracks quickly propagate, the same doesn’t occur at the nanoscale. Professor Gao explains, “At the nanoscale, cracks and flaws become so small that it takes much more energy to activate them and cause them to propagate.

“Nanoscale fibers also promote deformation mechanisms such as what is known as creep, where atoms can diffuse along grain boundaries, enabling the material to deform without breaking.”

The end result is a flexible sponge-like material that retains all the heat-resistant properties of traditional ceramics, enabling its use in a wide variety of high-temperature applications.

In order to make the ceramic sponges, the research team had to get creative. Electrospinning, a common method used in the creation of nanofibers, doesn’t work with ceramics, while 3-D laser printing techniques were deemed unsuitable due to their expense in terms of both time and money. Instead, the researchers made use of a technique known as blow-spinning, whereby air pressure is used to drive a liquid solution containing ceramic material through a tiny syringe aperture. The material quickly solidifies upon emerging and is collected in a spinning cage. Heating then burns away any residual solvents.

Using various forms of ceramics, the team were able to create sponges with some truly versatile properties, capable of rebounding from compressive strain up to 50% and enduring temperatures up to 800°C. This combination of flexibility and heat-resistance could make the material the ideal solution for applications such as insulating the garments of firefighters.

“The process we used for making these is extremely versatile; it can be used with a great variety of different types of ceramic starting materials,” said Hui Wu, one of the corresponding authors from Tsinghua. “So we think there's huge prospect for potential applications.”

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.