Formation of Ultra-High Temperature Ceramic Hollow Microspheres as Promising Lightweight Thermal Insulation Materials via a Molten Salt-Assisted Template Method

Review of Lightweight, High-Temperature Thermal Insulation Materials for Aerospace

Lightweight, high-temperature thermal insulation materials play a critical role in aerospace applications, where extreme temperature conditions necessitate lightweight, high-performance solutions. This paper explores advancements in lightweight, high-temperature insulation materials specifically designed for aerospace environments, focusing on innovative flexible ceramic fiber felts, thermal insulation tiles, nano-insulation materials (aerogels), and multilayer insulations (MLIs). These materials exhibit superior thermal resistance, low density, and durability under dynamic and harsh conditions. Key developments include the integration of nanostructures to enhance thermal conductivity control and improve mechanical stability. This paper also highlights applications in spacecraft thermal protection systems, providing insights into the challenges of future material design strategies. These advancements underscore the growing potential of thermal insulations to improve energy efficiency, safety, and performance in aerospace missions.

Interface Engineering Assisted 3D Printing of Silicone Composites with Synergistically Optimized Impact Resistance and Electromagnetic Interference Shielding Effectiveness

Silicone composites have been universally employed in smart devices, flexible electronics, and mechanical metamaterials. However, it remained challenging to develop 3D printable silicone composites with desirable mechanical and electrical properties. Here, an interface engineering strategy is reported, developing heterointerfacial silver-coated hollow glass microspheres (SHGMs), which are integrated with polydimethylsiloxane (PDMS) for 3D printing of impact-resistant, highly conductive, and mechanically robust SHGMs-PDMS (SHP) composites. SHP simultaneously achieves high compression modulus (12.65 MPa), substantial energy dissipation density (1.58 × 106 N m-2 at 50% strain), excellent conductivity (2.55 × 103 S m-1), and long-period robustness. SHP presents extraordinary impact resistance under dynamic impacts, reaching a considerable energy dissipation of 1.91 kJ m-1 at an incident velocity of 192.3 m s-1. More importantly, SHP with 2 mm in thickness achieves an ultraefficient electromagnetic interference (EMI) effectiveness of 92.5 dB, which is among that of state-of-the-art silicone and its derivatives, and can maintain favorable shielding efficiency (>70 dB) after undergoing mechanical excitations. Moreover, the formability enables it to fabricate delicate structures with a negative Poisson's ratio, ensuring adaptive fit and thus providing complete protection for individuals. This work paves an effective way to rapidly manufacture silicone composites with expected functions for new-generation protective devices.

Dual-Porosity (Ta0.2Nb0.2Ti0.2Zr0.2Hf0.2)C High-Entropy Ceramics with High Compressive Strength and Low Thermal Conductivity Prepared by Pressureless Sintering

Porous (Ta_0.2Nb_0.2Ti_0.2Zr_0.2Hf_0.2)C high-entropy ceramics (HEC) with a dual-porosity structure were fabricated by pressureless sintering using a mixture powder of ceramic precursor and SiO₂ microspheres. The carbothermal reduction in the ceramic precursor led to the formation of pores with sizes of 0.4-3 μm, while the addition of SiO₂ microspheres caused the appearance of pores with sizes of 20-50 μm. The porous HECs exhibit competitive thermal insulation (4.12-1.11 W·m^-1 k^-1) and extraordinary compressive strength (133.1-41.9 MPa), which can be tailored by the porosity of the ceramics. The excellent properties are ascribed to the high-entropy effects and dual-porosity structures. The severe lattice distortions in the HECs lead to low intrinsic thermal conductivity and high compressive strength. The dual-porosity structure is efficient at phonon scattering and inhabiting crack propagations, which can further improve the thermal insulation and mechanical properties of the porous HECs.