Fireproof and thermal insulation materials
At present, the main thermal insulation materials used for building exterior walls in China are extruded polystyrene foam plastic (XPS), molded polystyrene foam (EPS), polyurethane foam (PU), and other organic materials, as well as rock wool and glass microsphere, etc. organic materials. Traditional organic thermal insulation materials usually have the problem of being flammable, while inorganic thermal insulation materials have high density and are prone to losing insulation effect when absorbing water, making it difficult to simultaneously meet the requirements of insulation and fire resistance. To address this challenge, many scholars have proposed the idea of using aerogel as a fireproof and thermal insulation material.
1.1 SiO2 Aerogel Fireproof Thermal Insulation Materials
SiO2 aerogel, as a new type of thermal insulation material, has attracted widespread attention in the field of fireproof and thermal insulation due to its unique structure and excellent thermal conductivity.
Compared with traditional thermal insulation materials such as ceramic insulation layers, SiO2 aerogel shows more outstanding stability under high-temperature conditions and has remarkable fireproof and flame-retardant properties, making SiO2 aerogel have broad application prospects in the field of fireproof and thermal insulation.
However, SiO2 aerogel still has some problems in practical application, which need to be further studied and solved. In particular, its mechanical properties are poor and it is prone to be damaged by external forces, resulting in cracking when used in building exterior walls, which limits its application scope.
To address these issues, Cheng Kai et al. prepared hydrophobic modified SiO2 aerogel using the sol-gel method, with a water contact angle of up to 139°. The prepared SiO2 aerogel has an average pore diameter of up to 16.86 nm and a porosity of over 96%, with a minimum thermal conductivity of 0.0274 W/(mK), and has excellent insulation properties. However, hydrophobic modification may increase the preparation cost of SiO2 aerogel and may affect other properties, which needs to be considered comprehensively in practical applications.
In conclusion, the low thermal conductivity and high-temperature resistance of SiO2 aerogel make it a preferred material for fireproof and thermal insulation. The innovation of hydrophobic modification and assembly technology has enhanced the safety and stability of SiO2 aerogel in practical applications, opening up new avenues for the development of higher-performance thermal insulation materials. Future research should continue to focus on further improving the mechanical properties and environmental adaptability of SiO2 aerogel to achieve wider application in more fields.
1.2 Bio-based Aerogel Fireproof Thermal Insulation Materials
In recent years, the importance of bio-based materials has become increasingly prominent, as they not only provide a renewable and environmentally friendly alternative, but also often meet specific application requirements in terms of performance.
Cellulose is the most abundant renewable resource, which can be extracted from biomass materials such as wood, bamboo, and cotton. Studies have shown that cellulose-based aerogels have great potential in the field of thermal insulation and insulation.
In addition to cellulose-based aerogels, other bio-based materials have also made significant breakthroughs in fireproof and insulation fields. Yu Shuhong's team used pure natural imitation wood aerogels made from natural biomass and natural minerals to have excellent insulation and fire resistance properties. Their fire resistance temperature exceeds 1300 ℃, and they can remain exposed to flames for more than 20 minutes. This breakthrough is of great significance for the development of fireproof and insulation materials.
However, despite the environmental friendliness of bio-based aerogels as raw materials from renewable resources, the preparation process inevitably involves the use of organic solvents, which may cause pollution to the environment and require effective measures for control and treatment.
Through the rational design and modification of bio-based materials, environmentally friendly and efficient thermal insulation materials can be developed. Especially by adding flame retardants and adopting environmentally friendly preparation processes, the fire resistance performance of the materials can be significantly improved, which is of great significance for improving building safety standards and reducing fire risks.
1.3 Composite Aerogels
Combining different types of aerogels can obtain composite aerogels. Composite aerogels integrate the advantages of various aerogels, such as simultaneously possessing good mechanical strength and fire resistance, and can be applied in more demanding environments.
Zhang Ze's polydimethylsiloxane-polyimide composite aerogel, with its outstanding mechanical properties and high-temperature resistance, has brought a breakthrough in the field of fireproof insulation materials. This material not only has excellent compressibility but also shows extremely high thermal stability. Its decomposition temperature reaches 400 °C, and even when continuously burned in flames for 30 minutes, it can maintain the integrity of the structure, making it an ideal fireproof insulation material.
Through ingenious material design and modification, composite aerogel materials not only enhance fireproof insulation performance but also increase mechanical strength and durability, providing efficient and environmentally friendly solutions for building safety and energy conservation.
Fireproof and heat insulation materials
2.1 Fire protection for concrete components
Aerogel fireproof coatings are a special type of coating that forms a layer on the surface of the protected material, isolating the material from direct contact with air and delaying heat transfer, thereby increasing the fire resistance limit of the protected substrate.
However, in practical applications, the compatibility issue between aerogel fireproof coatings and concrete substrates cannot be ignored. Due to the complexity and diversity of concrete substrates, the adhesion between the coating and the substrate directly affects the fireproof effect of the coating.
By combining inorganic adhesives with dispersible latex powder, the stability adhesion of the coating on complex concrete substrates is effectively enhanced. However, further in-depth exploration is still needed on porosity, the mutual influence of coating components, and the durability and ability to adapt to harsh environments of the coating to promote its widespread application.
2.2 Fire protection for steel structures
Xu Guoqiang et al. prepared a new type of super insulation material using hard calcium silicate and SiO2 aerogels, and combined it with fireproof materials to form fireproof boards. This board has significant advantages in improving the fireproof performance of steel structures, with a fire resistance limit that is 2.5 times higher than traditional fireproof coatings, providing a higher-level fire protection for steel components.
2.3 Heat runaway prevention for lithium-ion batteries
Aerogels with excellent insulation and low flammability are highly favored in the field of lithium-ion battery thermal protection. A large number of studies have confirmed their potential application in suppressing the spread of lithium-ion battery heat runaway. By appropriately modifying the matrix of aerogel materials and combining them with the battery system, the fireproof performance of lithium-ion batteries can be effectively improved. Currently, aerogel fireproof partition materials such as ceramic fiber aerogel mats and glass fiber aerogel mats have been preliminarily applied in the fire protection of lithium-ion battery packs.
2.4 Fireproof and heat insulation for fire protection suits
Fire protection suits are an important barrier for firefighters to withstand harsh fire environments. Excellent heat insulation properties are one of the key characteristics that ensure the safety of firefighters. High-quality fire protection suits can effectively isolate flames and heat, reducing the risk of heat injury to the body, and providing necessary flexibility to ensure the freedom of movement of firefighters. With the advancement of materials science, new high-performance heat insulation materials such as aerogels are applied in fire protection suits, further improving the protection level and providing more reliable protection for firefighters in complex and variable fire environments.