Thermal insulation of the future could be lighter, more durable and able to withstand extreme conditions. Researchers have developed a scalable technique to develop ultralight fibrous materials, alumina/zirconia fibrous aerogels (AZFA), which could revolutionize thermal insulation in various industries.
Ceramic aerogels, like monolithic silica aerogels, are known to be ultralight solid materials with a density five to ten times that of air. These materials have attracted enormous interest due to their advantageous hardness and unmatched thermal insulation performance.
Traditional ultra-porous aerogels suffer from brittleness, structural degradation, moisture absorption, etc., making them virtually impossible to use in most applications.
The team of Nanomaterials by Design of the’University of Oxford addressed these limitations by using an innovative technique called 3D sol-gel electrospinning to create ultralight, flexible, fiber-assembled aerogels. This new approach enables the in situ formation of 3D fiber assemblies with a significant reduction in processing time and low processing cost compared to existing methods, providing a scalable and cost-effective solution for the production of advanced thermal insulators.
Fibrous aerogel materials (AZFA) feature an ultra-low density of up to 3.4 mg cm-3, superior flexibility and elasticity, and lower thermal conductivities than air – a combination of merits that surpasses most current insulators. What also sets AZFA apart is its ability to remain very flexible even at extremely high temperatures, up to 1300°C, and not melt or weld even at 1500°C, making it a key element for industries operating in extreme heat conditions.
Photograph of a piece of ultralight ceramic airgel placed on the pistils of a flower. (Image: Shiling Dong)
«The secret to AZFA’s thermal tolerance lies in its unique microstructure, with each fiber made of nanocrystalline zirconia and amorphous alumina. Additionally, the extraordinary mechanical resilience is imparted by the highly entangled and continuous 3D fiber network“, explains Dr. Barbara Maciejewska, who co-supervised the study.
Shiling Dong, the author of the article, points out that “One of the goals of this work is to solve the problem of humidity sensitivity of most existing aerogels. We have created self-cleaning hydrophobic materials that are durable in humid environments and can even be used as heat shields underwater, promising for, for example, underwater oil pipelines. These fibrous materials also have selective absorption properties that make them ideal for removing organic solvents from water.»
Professor Nicole Grobert, from the Department of Materials at the University of Oxford, believes that “the development of the 3D sol-gel electrospinning technique and the production of these innovative ultralight ceramic fibers represent a major advance in the field of thermal insulation.»
As industries seek innovative solutions to meet the growing need for better insulation, fibrous alumina/zirconia aerogels open up new possibilities. This discovery has the potential to transform industries by providing reliable insulation in the harshest conditions, improving energy efficiency and safety in various sectors.
For a better understanding
1. What is AZFA?
AZFA, or fibrous alumina/zirconia airgel, is an ultralight and flexible material developed by researchers at the University of Oxford. It has exceptional thermal insulation properties and can withstand extreme temperatures.
The researchers used an innovative technique called “3D sol-gel electrospinning” to create ultralight, flexible, fiber-assembled aerogels. This method enables the in situ formation of 3D fiber assemblies in a cost-effective and scalable manner.
3. What are the advantages of AZFA compared to other thermal insulators?
AZFA features ultra-low density, greater flexibility and elasticity, and lower thermal conductivities than air. It can also withstand extremely high temperatures and will not melt or weld even at 1500°C.
4. What are the potential applications of AZFA?
AZFA could be used in various industries, including automotive, skyscraper construction, aviation and aerospace. It could also be used as an underwater heat shield for underwater oil pipelines and to remove organic solvents from water.
5. What’s next for AZFA?
Researchers will continue to study and develop AZFA to further improve its properties and explore potential new applications. The goal is to transform industries by providing reliable insulation in the harshest conditions, improving energy efficiency and safety.
Main illustration caption: Washing contaminants from a self-cleaning hydrophobic ceramic airgel. (Image: Shiling Dong)
This study was accepted by Advanced Composites and Hybrid Materials: “3D Electrospinning of Al2O3/ZrO2 Fibrous Aerogels for Multipurpose Thermal Insulation“.
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