Ultrahigh-temperature ceramics were added to C/C composites to meet their application requirement in a high-temperature oxidizing environment. C/C-ZrB2-SiC composites were fabricated by high-solid-loading slurry impre...Ultrahigh-temperature ceramics were added to C/C composites to meet their application requirement in a high-temperature oxidizing environment. C/C-ZrB2-SiC composites were fabricated by high-solid-loading slurry impregnation with polymer infiltration and pyrolysis. The dispersion and rheological behavior of ZrB2 slurry and the microstructural, mechanical, and ablation properties of the C/C-ZrB2-SiC composites were investigated. Results indicated that a well-dispersed and low-viscosity ZrB2 slurry was obtained using 0.40 wt.% polyethyleneimine as a dispersant at pH 5. Ceramics were uniformly distributed in the short-cut fiber layer and needle-punched area. The flexural strength of the C/C-ZrB2-SiC composites was 309.30 MPa. The composites exhibited satisfactory ablation resistance under the oxyacetylene flame of 2500℃, and the mass and linear ablation rates were 0.40 mg/s and 0.91 μm/s, respectively. A continuous and compact Zr O2 layer, which could effectively reduce the diffusion rate of oxygen and protect the composites from being ablated, was formed.展开更多
The novel Ni-based brazing filler was used to join C/C composites.When brazing temperature increased from 1080 to 1100°C,the wetting angle decreased from 23°to 14°,and the brazing filler had good wettab...The novel Ni-based brazing filler was used to join C/C composites.When brazing temperature increased from 1080 to 1100°C,the wetting angle decreased from 23°to 14°,and the brazing filler had good wettability on the surface of C/C composites.The brazing seam of the brazed joint consisted of Ni(s,s)and Cr_(3)C_(2) phases.As brazing temperature increased,lots of Cr_(3)C_(2) phases were generated at the bonding interface,and the thick reaction layer was formed.When brazing temperature was 1120°C,the shear strength of C/C joint reached the maximum value of 31.5 MPa.The fracture path extended in the C/C matrix close to the bonding interface.展开更多
基金Project(GFZX0101040101-2012C20X) supported by the National Basic Research Program of ChinaProject(2017JJ2320) supported by the Natural Science Foundation of Hunan Province,China
文摘Ultrahigh-temperature ceramics were added to C/C composites to meet their application requirement in a high-temperature oxidizing environment. C/C-ZrB2-SiC composites were fabricated by high-solid-loading slurry impregnation with polymer infiltration and pyrolysis. The dispersion and rheological behavior of ZrB2 slurry and the microstructural, mechanical, and ablation properties of the C/C-ZrB2-SiC composites were investigated. Results indicated that a well-dispersed and low-viscosity ZrB2 slurry was obtained using 0.40 wt.% polyethyleneimine as a dispersant at pH 5. Ceramics were uniformly distributed in the short-cut fiber layer and needle-punched area. The flexural strength of the C/C-ZrB2-SiC composites was 309.30 MPa. The composites exhibited satisfactory ablation resistance under the oxyacetylene flame of 2500℃, and the mass and linear ablation rates were 0.40 mg/s and 0.91 μm/s, respectively. A continuous and compact Zr O2 layer, which could effectively reduce the diffusion rate of oxygen and protect the composites from being ablated, was formed.
基金the financial support from the National Natural Science Foundation of China (Nos. 51675030, 51871010, 52005022)Shanghai Aerospace Scienceand Technology Innovation Fund, China (No. SAST2020-117)。
文摘The novel Ni-based brazing filler was used to join C/C composites.When brazing temperature increased from 1080 to 1100°C,the wetting angle decreased from 23°to 14°,and the brazing filler had good wettability on the surface of C/C composites.The brazing seam of the brazed joint consisted of Ni(s,s)and Cr_(3)C_(2) phases.As brazing temperature increased,lots of Cr_(3)C_(2) phases were generated at the bonding interface,and the thick reaction layer was formed.When brazing temperature was 1120°C,the shear strength of C/C joint reached the maximum value of 31.5 MPa.The fracture path extended in the C/C matrix close to the bonding interface.
