[en] Highlights: • ZrC-rich surface layer with a thickness of 100 μm was obtained in C/C composites. • ZrC-rich surface layer improves the ablation resistance of the C/C composites. • ZrC-rich layer seal the surface defects to restrain the ablation of defects area. • Strengthened ZrC-rich surface layer reduces the mechanical denudation. - Abstract: Zirconium carbide (ZrC) rich surface layer with a thickness of 80–100 μm was prepared on carbon/carbon (C/C) composites. The ZrC-rich layer consisted of submicron ZrC particles, homogeneously dispersed in the carbon matrix. The mass ablation rate of the composite with the ZrC-rich layer was 69% lower than that of the bare C/C composites. The ZrC-rich layer could seal the surface pores and cracks to restrain the preferential ablation in the defect area and form a continuously melting ZrO₂ layer to prevent the carbon from oxidizing during ablation. The strengthened ZrC-rich layer could reduce the mechanical denudation of the composites

[en] The V₂O₅ self-assembled nanosheets (SANs V₂O₅) were synthesized by an additive-free ultrasonic method with subsequent thermal decomposition. The loose nanostructured V₂O₅ is multi-layer structure stacked by 4∼6 layers with a thickness of 200∼300 nm and each layer is composed by abundant nanoparticles in order. Due to this unique layered structure, the SANs V₂O₅ exhibits remarkable rate performance and excellent cycling stability. Specifically, it delivers reversible discharge capacities of 157.2 and 111.6 mAh g⁻¹ at current densities of 2C and 5C. After 300 cycles, it still maintained high capacities of 123.5 and 85.1 mAh g⁻¹, which corresponds to a capacity loss of 0.07% and 0.08% per cycle, respectively. In addition, even at 10C, it displays a capacity of 68.8 mAh g⁻¹ and 87.9% of the capacity (60.5 mAh g⁻¹) is remained after 300 cycles. All the results indicate the V₂O₅ self-assembled nanosheets could be a promising candidate as cathode active material for long-term cycling performance in Lithium-ion batteries.

[en] Highlights: • The C/C-Zr-Si-O with a density of 1.71g/cm³ was obtained by 8 cycles of hydrothermal co-deposition/carbothermal reduction. • The mass ablation rate of the composites was as low as 0.112 mg/cm²·s owing to the fine grain and homogeneous Zr and Si. • The formation of ablation bubbles is significant to achieve the attractive ablation resistance of the composites. C/C-Zr-Si-O composites were prepared by carbothermal reduction of hydrothermal co-deposited ZrO₂, SiO₂, and C. The bulk density of composites reached 1.71 g/cm³ with 8 cycles of co-deposition. The matrix of the composites includes ZrC, SiC, ZrO₂, and SiO₂ with fine grain size (300–500 nm) and homogeneous distribution. The mass and linear ablation rate of C/C-Zr-Si-O composites were 0.112 mg/cm²·s and 0.46 μm/s, respectively, under a plasma flame for 120 s. The attractive ablation resistance of the composites resulted from its unique structure, which tends to form a continuous ZrO₂-SiO₂ glass layer in the ablation center, a layer of SiO₂-ZrO₂ bubbles in the transition region, and fluffy SiO₂ nanowires layer in the heat-affected region. These ablation layers were barriers to restrain the diffusion of oxidative gas and heat. The C/C-Zr-Si-O composites provide an alternative ceramics system with attractive ablation resistance, while carbothermal reduction of hydrothermal co-deposited oxides is a feasible method for the structural design of carbon fiber reinforced ultra-high temperature ceramic.

[en] Highlights: • C/C-ZrC composites were prepared by hydrothermal deposition of ZrO₂ and carbon. • Sub-micrometer ZrC particles were uniformly dispersed in the matrix. • The composites presented a typical pseudo-plastic fracture behavior. • Formation of ZrO₂ glass and ZrO₂ skeleton layer reduce the ablation of composites. Carbon fiber reinforced carbon matrix containing ZrC (C/C–ZrC) composites were prepared by hydrothermal deposition combined with carbothermal reduction. The submicron ZrC particles (100–300 nm) were dispersed in the matrix. The stress-strain curves of the composites presented a typical pseudo-plastic fracture behavior. The mass and linear ablation rates of the composites were 3.7 × 10⁻³ g/s and 4.2 × 10⁻³ mm/s, respectively. The formation of ZrO₂ glass layer reduced erosion of the composites in the ablation center. The continuous C–ZrC–ZrO₂ skeleton layer generated from the oxidation of ZrC can protect the composites from erosion at the ablation brim region. The obtained C/C–ZrC composites present a promising potential as ablation resistance materials.