Zirconia Aerogels

• Published in: Springer Handbook of Aerogels pp. 459 - 476
• Main Authors: Ben Hammouda, Lassaad, Mejri, Imen, Younes, Mohamed Kadri, Ghorbel, Abdelhamid
• Format: Book Chapter
• Language: English
• Published: Cham Springer International Publishing 2023
• Series: Springer Handbooks
• Subjects: Aerogel; Catalysis; Coating; Sol–gel; Supercritical drying; Zirconia
• ISBN: 9783030273217; 3030273210
• ISSN: 2522-8692; 2522-8706
• DOI: 10.1007/978-3-030-27322-4_19

Zirconia aerogels are very promising materials in industry with exceptional properties related to their high porosity, important surface area, and thermal stability in addition to their low density and thermal conductivity. All of these properties explain the wide potential applications of these aerogels such as catalysis, ceramics, solid oxide fuel cells (SOFCs), optics, thermal barrier coatings (TBC), and many other high-temperature applications. For several years, the preparation of zirconium aerogels was carried out using zirconium alkoxide precursors or inorganic salts through a sol–gel process followed by a supercritical drying (SCD) method in order to preserve the porous network of the final product. However, it has been reported that the synthesis procedures relying on inorganic salts as starting materials are generally nontoxic, inexpensive, more practical, and easier to develop and allow at the same time, after supercritical drying of the corresponding gels, to better aerogels with respect to surface area and nanoporous structure. Furthermore, the SCD process presents a major handicap when it is set up on an industrial scale, related to the use of a high-pressure autoclave for the drying. Therefore, this has prompted many researchers to develop a new method to produce “aerogels” by ambient pressure drying (APD). During the last 20 years, many research groups interested by zirconia aerogels and their potential applications confirmed that the tetragonal crystal phase of ZrO2 seems to be the most interesting phase. However, it has been reported that the textural and structural properties of zirconia aerogels depend on several preparation parameters such as the zirconium precursor and its concentration, the type of solvent, the use of complexing or silylating agents, the acid concentration, the hydrolysis ratio in the case of sol–gel process, the gel aging time, and the SCD temperature.