ZHU Jinming ¹, MA Sheng ³, DONG Gang ^{1, 2}, LI Kun ¹, LIAO Wenzhuo ¹, SHI Wei ¹,

LU Xilong ¹, ZENG Tao ^{1 ,2}, CHEN Yunxia ^{1, 2}

(1. School of Materials Science and Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, Jiangxi, China;

2. Jiangxi Provincial Key Laboratory of Advanced Ceramic Materials, Jingdezhen 333403, Jiangxi, China;

3. Jingdezhen Central Automatic Monitoring Group, Jiangxi Ecological Environmental Monitoring Center,

Jingdezhen 333000, Jiangxi, China)

Extended abstract:

[Significance] As a core material for next-generation thermal management, ceramic aerogels, with their low density, high porosity, low thermal conductivity, excellent weather resistance and tunable porous structure, demonstrate enormous potential to replace traditional thermal insulation materials, which can be applied in aerospace thermal protection, personal thermal management and radiative cooling. Furthermore, they offer innovative solutions for thermal regulation in extreme environments and show promise in catalytic carriers and filtration separation. Thermal management performance of ceramic aerogels is dependent on their microstructure and chemical composition, with the integrity and stability of the three-dimensional nanonetwork framework directly affecting insulation efficiency and high-temperature tolerance. This paper was aimed to categorize ceramic aerogels into two main types based on their composition: oxide ceramic aerogels and non-oxide ceramic aerogels. Oxide ceramic aerogels are easier to prepare and scale up, while non-oxide ceramic aerogels, although being more difficult to prepare, possess both high-temperature stability and structural rigidity, forming a complementary relationship. The core structure of ceramic aerogels is a three-dimensional nanonetwork framework. Traditional oxide ceramic aerogels are mostly assembled from nanoparticles in a beaded structure, mainly connected by van der Waals forces, while non-oxide ceramic aerogels are formed through covalent bonds to build the framework, resulting in high bond energy and structural stability. This structural characteristic determines the performance differences between the two types of ceramic aerogels. Currently, ceramic aerogels could be oxide, non-oxide and composite systems, with applications extending to multiple fields, such as aerospace SiC nanowire aerogels that can withstand temperatures up to 1600 ℃, biomimetic multilayer structures (BMS) for personal thermal management that can maintain temperatures above 20 ℃ for 0.5–2.5 h at −20 ℃ and radiation-cooled SiO₂-Al₂O₃ all-ceramic nanofiber aerogels (SAFA) that can achieve a cooling effect of 8 ℃ below ambient temperature. However, current ceramic aerogel technology still lags behind large-scale commercial applications, highlighting performance challenges in the field of thermal management and outlining future research directions.

[Progress] This paper was first to introduce the classification, basic properties and structural characteristics of ceramic aerogels. Then, it was to elaboratethe influence of microstructural parameters and modification strategies on their thermal stability, mechanical strength and thermal conductivity. Next, oxide ceramic aerogel systems were classified, highlighting SiO₂ and its composite aerogels for their high specific surface area, high porosity and low thermal conductivity. For Al₂O₃ and its composite aerogels, the effects of preparation processes, composite component ratios and doping elements on their high-temperature stability and thermal insulation performance were discussed. For ZrO₂ and its composite aerogels, the high-temperature application potential, brought by their high melting point were analyzed, while the structural stability principle under extreme high temperatures were revealed. Subsequently, non-oxide ceramic aerogel systems and their core properties ere introduced, exploring methods for improving mechanical properties and control methods for large-scale applications. Finally, the current research status of ceramic aerogels in the field of thermal management were reviewed, while the optimization methods for extreme environment adaptation in the aerospace field were discussed. For personal insulation and radiative cooling, thermal regulation characteristics and performance optimization paths of different composite structures were analyzed, whilt their practical application potential with case studies were illustrated.

[Conclusions and prospects] This article was aimed to review the research progress of ceramic aerogel materials and their applications in thermal management. Ceramic aerogels, as advanced three-dimensional high-porosity materials, have enormous application potential in thermal management. However, current research indicates that their performance and applications still face bottlenecks. Oxide ceramic aerogels typically have low mechanical strength and are prone to phase transformation and sintering at high temperatures, leading to decline in thermal insulation performance. Non-oxide ceramic aerogels have cumbersome preparation processes and high costs and are easily oxidized in high-temperature aerobic environments. Furthermore, their synthesis mechanisms and network structure growth patterns are not yet fully understood. Future research should focus on fiber reinforcement and multiphase composite optimization techniques for oxide ceramic aerogels, development of efficient and low-cost large-scale preparation methods for non-oxide ceramic aerogels and deep exploration of the growth mechanisms of the material’s network structure and the regulation of high-temperature stability to promote their practical applications in thermal management and other broader fields.

Key words: ceramic aerogel; oxide ceramic aerogel; non-oxide ceramic aerogel; thermal management