Aerogels are the lightest solids in the world, more than 90 percent of the structure of which is composed of air. They are made by carefully replacing the liquid from a gel with gas. The materials produced in this way are also called “frozen smoke” because of their unique, translucent appearance. They are extremely good thermal insulators and block heat very effectively. Although they appear fragile to the touch, they have a surprisingly high weight-bearing capacity, holding up even a thousand times their own weight.
Aerogels are used today in more and more places. In the construction industry, they take care of insulation. In space exploration, they protect spacecraft and aerospace instruments sensitive to extreme cold or extreme heat. In industry, they are used to minimize heat loss in steam pipes and tanks. In electric cars, they prevent the spread of heat generated in batteries. Due to their large internal surface area, they are also suitable for effectively absorbing oil spills and a variety of chemicals.
Recently, the thermal properties, thermal stability and various engineering applications of aerogels were investigated at the Faculty of Engineering of the University of Debrecen. The results were summarized in an article, which Ákos Lakatos, Head of the Department of Building Services and Building Engineering, described to hirek.unideb.hu as follows. After aging the samples at 150 and 250 degrees Celsius for one day, the changes were monitored the in the thermal and physical characteristics of Slentex insulation. The data thus gained allowed to identify changes in both the structural and the thermal properties as well as to examine possible correlations between these two properties.
- We identified observable and quantifiable surface and structural changes of the Slentex fiber. The Cp measurements supported the amorphization process, which showed a 10% change after one day of heat treatment at 250 degrees Celsius, as well as a heavily oxidized surface on the sample. The results of thermal conductivity measurements showed stable thermal insulation and amorphization, while specific heat capacity changed only slightly after aging. Both of these are due to the amorphous nature of the state. We derived the diffusion and volumetric heat capacity from these thermal values. The results showed an approximately 3 to 4 percent decrease in thermal diffusion, while the volumetric heat capacity increased- said Ákos Lakatos, Professor at the Faculty of Engineering of the University of Debrecen.
Professor Lakatos added that, during the course of the examination, microscopic and visual analysis had revealed surface oxidation, while the so-called differential scanning calorimetry results had showed a significant and continuous increase in the heat flow curve and a strong heat absorption process.
According to the Head of the Department of Building Services and Building Engineering, aerogel developers in the future need to focus on developing hybrid systems, improving moisture barrier layers and developing low-carbon emission methods.
The findings of the researchers were published in an article under the heading Case Studies in Thermal Engineering in the English-language scientific journal PlumX Metrics, the full text of which you can find here. The efforts and achievement of the research team have been recognized with a Publication Award by the Count István Tisza Foundation for the University of Debrecen and the University of Debrecen.
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