How AZFA can change modern thermal insulation
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How AZFA can change modern thermal insulation

The insulation of the future could be lighter, stronger and able to withstand extreme conditions. Researchers have developed a scalable technology to develop ultra-lightweight fibrous materials—aluminum oxide zirconia fiber aerogels (AZFA)—that could revolutionize thermal insulation across a variety of industries.

Ceramic aerogels, like monolithic silica aerogels, are known to be ultra-light solid materials with a density five to ten times that of air. These materials have attracted enormous interest due to their exceptional hardness and unrivaled thermal insulation properties.

Traditional ultraporous aerogels suffer from brittleness, structural degradation, moisture absorption, etc., making them virtually impossible to use in most applications.

Team Nanomaterials by design from the University of Oxford have addressed these limitations by using an innovative technique called 3D sol-gel electrospinning to create ultra-lightweight, flexible aerogels assembled from fibres. This new approach allows 3D fiber assemblies to be formed in-situ with significantly reduced processing time and low processing cost compared to existing methods, providing a scalable and cost-effective solution for the production of advanced thermal insulators.

Exceptional performance

Fibrous airgel materials (AZFA) have ultra-low densities of up to 3.4 mg/cm3, excellent flexibility and elasticity, and lower thermal conductivity than air – a combination of advantages that is superior to most modern insulators. What also sets AZFA apart is its ability to remain highly 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 hot environments.

Photograph of a piece of ultra-light ceramic airgel placed on the pistils of a flower. (Image: Shilin Dong)

The secret to AZFA’s heat resistance lies in its unique microstructure, where each fiber is composed of nanocrystalline zirconium and amorphous alumina. In addition, exceptional mechanical stability is ensured by a highly entangled and continuous 3D fiber network.“, explains Dr. Barbara Maciejewska, who led the study.

Promising applications

Shilin Dong, the author of the article, notes that “One of the goals of this work is to solve the problem of sensitivity to humidity of most existing aerogels. We have created self-cleaning hydrophobic materials that are durable in wet environments and can even be used as heat shields underwater, which is promising, for example, for undersea oil pipelines. These fibrous materials also have selective absorption properties, making them ideal for removing organic solvents from water.»

Professor Nicole Grobert from the Department of Materials at Oxford University believes that “The development of 3D sol-gel electrospinning technology and the production of these innovative ultra-lightweight ceramic fibers represent a major advance in the field of thermal insulation.»

Synthetic

As industries seek innovative solutions to meet the growing need for better insulation, aluminum oxide and zirconium oxide fiber aerogels are opening up new possibilities. This discovery could change the industry by providing reliable insulation in the harshest environments, improving energy efficiency and safety in various sectors.

For better understanding

1. What is AZFA?

AZFA, or aluminum oxide fiber airgel, is an ultra-lightweight 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 aerogels assembled from fibers. This method allows for cost-effective and scalable in-situ fabrication of 3D fiber optic assemblies.

3. What are the advantages of AZFA compared to other thermal insulators?

AZFA has ultra-low density, greater flexibility and elasticity, and lower thermal conductivity 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 can be used in a variety of industries including automotive, skyscraper construction, aviation and aerospace. It can also be used as a subsea heat shield for subsea 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 new potential applications. The goal is to transform industries by providing reliable insulation in the harshest environments, improving energy efficiency and safety.

Caption for main illustration: Washing away contaminants from self-cleaning hydrophobic ceramic airgel. (Image: Shilin Dong)

This research has been accepted by Advanced Composites and Hybrid Materials: “3D Electrospinning of Al2O3/ZrO2 Fiber Aerogels for Multi-Purpose Thermal Insulation.”

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