The thermomechanical properties of carbon fiber reinforced silicon carbide ceramic matrix composites (C_f/SiC CMCs) were studied up to 2000 °C using high-temperature in situ flexural testing in argon. The CMC specimens were fabricated using an ultrahigh concentration (66 vol%) aqueous slurry containing nano-sized silicon carbide powder. The SiC powder compacts were obtained by drying the slurry and were densified using the precursor impregnation and pyrolysis (PIP) method with field assisted sintering technology/spark plasma sintering (FAST/SPS). The high relative density of the SiC green body (77.6%) enabled densification within 2.5 days using four PIP cycles. In contrast, conventional PIP processes take over 7 days. The in situ flexural strength of the C_f/SiC CMC was 434 MPa at 1750 °C, which was 84% higher than the room temperature value. The value further increased to 542 MPa at 2000 °C. Possible mechanisms to explain the excellent strength of the CMC at elevated temperatures are discussed.

Among the various metal oxide nanomaterials, manganese oxides, which can exist in different structures and valence states, are considered highly promising anode materials for lithium-ion batteries (LIBs). However, conventional manganese oxides, such as MnO and MnO₂, face significant challenges during the cycling process. Specifically, poor electronic conductivity and large volume changes result in low specific capacity during high current charging and discharging, as well as poor fast-charging performance. This work presents an approach to synthesizing porous hexagonal Mn₅O₈ nanosheets using hydrothermal and annealing methods and applies them as anode materials for LIBs. The Mn₅O₈ nanomaterials exhibit a thin plate morphology, which effectively reduces the distance for ion/electron transmission and mitigates the phenomenon of volume expansion. Additionally, the large pore size of Mn₅O₈ results in abundant interlayer and intralayer defects, which further enhance the rate of ion transmission. These unique characteristics enable Mn₅O₈ to demonstrate excellent electrochemical performance (938.7 mAh×g^-1 after 100 cycles at 100 mA×g^-1) and fast charging performance (675.7 mAh×g^-1 after 1000 cycles at 3000 mA×g^-1), suggesting that Mn₅O₈ nanosheets have the potential to be an ideal fast-charging anode material for LIBs.

TiC provides a promising potential for high-temperature microwave absorbers due to its unique combination of thermal stability, high electrical conductivity, and robust structural integrity. C@TiC/SiO₂ composites were successfully fabricated using a simple blending and cold-pressing method. The effects of C@TiC’s absorbent content and temperature on the dielectric and microwave absorption properties of C@TiC/SiO₂ composites were investigated. The addition of C@TiC from 10 wt.% to 30 wt.% not only endows the composites with a higher dielectric constant and dielectric loss, but also with a greater high-temperature stability in terms of dielectric and microwave absorption properties. The composite with 30 wt.%C@TiC demonstrates a strong microwave absorption capability with a minimum reflection loss (RL_min) of −55.87 dB, −48.49 dB, and −40.36 dB at room temperature, 50 °C, and 100 °C, respectively; the 50 wt.%C@TiC composite exhibits an enhanced high-temperature microwave absorption performance with an RL_min of −16.13 dB and −15.72 dB at 200 °C and 300 °C, respectively. This study demonstrates that the TiC-based absorbers present an innovative solution for high-temperature microwave absorption, providing stability, versatility, and adaptability in extreme operational environments.

A novel amorphous Hf-MOFs precursor was successfully synthesized and converted into HfC nanoparticles via one-step pyrolysis. The effects of metal/ligand molar ratios, solvent types, and pyrolysis temperature were systematically studied. High-purity spherical HfC nanoparticles (44.30 ± 9.63 nm) were obtained at 1500 °C using a 1.5:1 metal/ligand molar ratio with mixed anhydrous ethanol/deionized water solvents. At a pyrolysis temperature of 1700 °C, the as-synthesized HfC nanoparticles possessed an exceptionally low oxygen content of 0.76%, alongside a carbon content of 6.42% that almost perfectly matches the theoretical value of stoichiometric HfC. The formation mechanism involving Hf-O-C coordination and carbothermal reduction was clarified. Additive-free HfC ceramics were fabricated using the as-synthesized HfC nanoparticles via spark plasma sintering (1950 °C, 30 MPa, 20 min). The resulting ceramics exhibited a relative density of 96.7% and a Vickers hardness of 20.2 GPa, both of which are significantly superior to those of ceramics sintered from commercial HfC powders under identical conditions (95.8% and 17.8 GPa, respectively). This work provides a promising and feasible pathway for the preparation of other high-quality ultra-high temperature hafnium-based carbide powders and ceramics.