Advanced thermal management via directional freezing for high-strength infrared-modified alumina aerogels

Traditional aerogels are constrained by compromised mechanical properties, while their low-density skeletons exhibit insufficient infrared reflectance that leads to a rapid increase in radiative thermal conductivity at elevated temperatures. We present directionally laminated TiO₂ infrared-modified Al₂O₃ aerogels (TAAs) with oriented layered structure fabricated through directional freezing. The optimized processing parameters determined by experimental and simulation results include: 20° substrate inclination angle, 0.5 wt% hydroxyethyl cellulose additive, and −60 °C freezing temperature. The directional freezing technique creates structurally aligned channels along specific orientations, resulting in remarkable mechanical anisotropy with 4–6 times higher strength in the designed direction compared to other orientations. Compositional modification through TiO₂ incorporation effectively suppresses infrared radiative heat transfer, achieving a significant reduction of infrared transmittance from 73.73 % to 27.06 %. The dual optimization in structural architecture and chemical composition synergistically improves both the mechanical integrity and thermal insulation performance of TAAs. This design strategy provides an attractive solution for developing advanced thermal management materials in extreme environments.