In recent years, aerogel materials have shown great application potential in aerospace, energy and environmental protection, building insulation and other fields due to their unique nanoporous structure, extremely low thermal conductivity and excellent mechanical properties. However, aerogels have many performance parameters, and different application scenarios have different requirements for their key performance. So, when choosing aerogel materials, which performance indicators are the most critical? Is it ultra-low thermal conductivity, excellent mechanical strength, or excellent hydrophobicity or environmental stability? This article will analyze the core performance of aerogels, explore the key points of material selection in different application scenarios, and provide readers with scientific and practical selection suggestions to help them make the best decisions in scientific research or engineering practice.
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3. High temperature resistance and flame retardancy
5. Application-specific requirements
The core value of aerogel lies in its ultra-low thermal conductivity (0.013–0.03 W/m·K), making it one of the best known solid-state materials for thermal conductivity, and it can effectively block three heat transfer modes: conduction, convection, and radiation. Taking silica aerogel as an example, its extremely low thermal conductivity enables it to play a key role in aerospace, energy, and other fields. For example, the Zhurong Mars rover uses aerogel to protect key components, allowing it to work stably in extreme environments ranging from -100°C to high temperatures. In the field of power batteries, the thermal conductivity of aerogel insulation pads usually needs to be controlled below 0.03 W/m·K to effectively suppress the risk of thermal runaway. However, in high temperature environments (>600°C), the thermal insulation performance of some organic aerogels will drop significantly, so it is necessary to use composite high-temperature resistant materials to improve their high-temperature stability. These characteristics make aerogel an irreplaceable key material in scenarios with extreme thermal insulation needs.
The mechanical properties of aerogels are mainly reflected in tensile strength, compression resilience and fracture resistance, which directly affect their durability and processing adaptability in practical applications. Pure aerogels usually show high brittleness, and their tensile strength is often less than 0.1 MPa, which is difficult to meet engineering requirements. Therefore, they often need to be compounded with fiber materials to enhance the mechanical properties. For example, aramid fiber-reinforced aerogel composites can increase the tensile strength to 1.2 MPa, and have been successfully used in harsh environments such as nuclear submarine insulation layers. The tensile strength of optimized aerogel composites can reach 0.5-2 MPa, which can meet the material strength requirements of construction, aerospace and other fields. However, it should be noted that the mechanical reinforcement process may partially sacrifice its excellent thermal insulation performance due to the reduction of porosity. Therefore, it is necessary to balance the mechanical strength and thermal insulation performance during design.
3. High temperature resistance and flame retardancy
The high temperature resistance and flame retardant properties of aerogels are mainly reflected in the structural stability of the material and its ability to inhibit combustion in high temperature environments. Aerogels of different compositions show significantly different temperature resistance characteristics. Taking polyimide aerogel as an example, its temperature resistance can reach 600°C, while carbon aerogel can remain stable under extreme conditions exceeding 3000°C, showing excellent high temperature resistance potential. In terms of flame retardant properties, high-quality aerogels must meet strict specifications such as UL 94 V-0 or building fire protection standards to ensure their safety in fire scenarios. However, it should be noted that organic aerogels are at risk of decomposition at high temperatures, and their stability is usually not as good as that of inorganic aerogels. Therefore, the material system should be carefully selected when used in high temperature applications. It is worth noting that some specially modified aerogels, such as cellulose-based aerogels, can not only maintain their performance at high temperatures of 600°C, but also have biodegradable properties. This unique combination makes it show important application value in emerging fields such as infrared stealth.
The cost and scalability of aerogels are mainly affected by the cost of material production, the potential for scale-up, and the maturity of the supply chain. The industry is still facing the challenge of balancing high costs with industrialization. As a traditional preparation method, the cost of supercritical drying accounts for up to 40% of the total cost, while the emerging atmospheric drying technology can reduce the production cost by about 30%, providing the possibility for large-scale application. China has become the country with the largest aerogel production capacity in the world, with a production capacity of 500,000 cubic meters in 2023, but it still relies on imports in the field of high-end products, reflecting the gap between the level of industrialization and core technology. It is worth noting that although low-cost solutions have improved economic efficiency, they often come at the expense of material performance consistency. International leading companies such as Aspen Aerogel have successfully achieved large-scale production through fiber composite technology, keeping costs at $50/square meter, providing the industry with a reference industrialization path, but how to further reduce costs while ensuring performance is still a key issue for large-scale commercial application of aerogels.
5. Application-specific requirements
The application-specific requirements of aerogels are reflected in customized performance optimization for different usage scenarios, such as special functional requirements such as sound absorption, electromagnetic shielding or chemical stability. In the field of aerospace, lightweight is the core demand, and the density of aerogels is usually required to be less than 100 kg/m³, while architectural applications pay more attention to the ease of material processing, and often require aerogels to be prefabricated into sheet form for easy construction. In order to achieve the electromagnetic shielding function, conductive fillers need to be added to the aerogel, but this usually comes at the expense of some thermal insulation performance. It is worth noting that the nanoporous structure of aerogels gives it excellent sound absorption performance, with a sound absorption coefficient of up to 0.95 (2000 Hz). This feature has been successfully applied to scenes that require noise reduction, such as high-speed rail carriages. However, although integrating multiple functions into a single aerogel material can expand the scope of application, it will inevitably increase the complexity of the preparation process and the overall cost, which has become the main bottleneck restricting the commercial application of multifunctional aerogels.
Aerogel materials, with their ultra-low thermal conductivity, lightweight porous structure, and adjustable mechanical and functional properties, have shown irreplaceable application value in cutting-edge fields such as aerospace, new energy, and building insulation. However, their actual selection requires comprehensive consideration of multi-dimensional factors such as thermal conductivity, mechanical strength, temperature resistance and flame retardancy, cost-effectiveness, and functional requirements of specific scenarios. In the future, with breakthroughs in low-cost preparation technologies such as atmospheric pressure drying, and the optimization of reinforcement processes such as fiber composites and nano-modification, aerogel materials are expected to achieve greater breakthroughs in the balance between performance and cost, and promote their large-scale application in a wider range of industrial fields. How to accurately match application requirements in the material design stage will become a core issue of common concern to scientific research and industry.