Hierarchical Composite with Self-Adaptive Anisotropic Deformation for Thermal Protection System.

Rigid thermal protection materials such as ultra-high-temperature ceramics are desirable for applications in aerospace vehicles, but few materials can currently satisfy the emerging high-temperature sealing requirements for dynamic gaps created by the mismatch of the thermal expansion of different protection layers. Here, we design and fabricate a flexible biomimetic anisotropic deformation composite by multilayer cocuring onto fiber fabrics. It displays superior anisotropic deformation, whose longitudinal expansion ratio is 48 times greater than the transverse expansion ratio at specific temperatures.

Flexible Thermal Protection Polymeric Materials with Self-Sensing and Self-Adaptation Deformation Abilities.

Based on the strategy of killing two birds with one stone, we introduce thermally expandable microspheres into a silicone rubber matrix to fabricate temperature-responsive controllable deformation materials, which exhibit intelligent deformation properties as well as enhanced thermal protection performance, for dynamic thermal protection in the next-generation morphing aircrafts. The formation of hollow structures endows the material with intelligent thermal management ability and makes the thermal conductivity controllable, meeting the requirements of rapid deformation and excellent thermal insulation. The dimensions of the material adaptively expand with increasing temperature, and a constant 50N force can be provided to ensure reliable sealing.

Improving Thermal Conductivity of Injection Molded Polycarbonate/Boron Nitride Composites by Incorporating Spherical Alumina Particles: The Influence of Alumina Particle Size.

In this work, the influences of alumina (AlO) particle size and loading concentration on the properties of injection molded polycarbonate (PC)/boron nitride (BN)/AlO composites were systematically studied. Results indicated that both in-plane and through-plane thermal conductivity of the ternary composites were significantly improved with the addition of spherical AlO particles. In addition, the thermal conductivity of polymer composites increased significantly with increasing AlO concentration and particle size, which were related to the following factors: (1) the presence of spherical AlO particles altered the orientation state of flaky BN fillers that were in close proximity to AlO particles (as confirmed by SEM observations and XRD analysis), which was believed crucial to improving the through-plane thermal conductivity of injection molded samples; (2) the presence of AlO particles increased the filler packing density by bridging the uniformly distributed BN fillers within PC substrate, thereby leading to a significant enhancement of thermal conductivity.