Effects of SiC content on the mechanical and thermophysical properties of 3D Cf/SiC-Al composites

3D C-f/SiC-Al composites were achieved through the pressure infiltration of liquid Al-Si alloy into porous 3D C-f/SiC preform, which was produced by different cycles of precursor infiltration and pyrolysis. The effect of silicon carbide volume fraction on the microstructure, anisotropic mechanical response, and thermophysical characteristics of the 3D C-f/SiC-Al composites was investigated. The results demonstrated that the initial microstructure of 3D C-f/SiC can be retained, and the obtained C-f/SiC-Al composites presented remarkable anisotropy characteristics. As the silicon carbide ceramics content increased from 12.5 vol% to 41.8 vol%, the thermal conductivity and thermal expansion coefficient of 3D C-f/SiC-Al composites decreased, whereas the bending strength initially increased and then decreased in the Z-direction. The bending strength perpendicular (Z) to the carbon cloth layer of 3D C-f/SiC-Al composites was higher than that of parallel (X-Y) to the carbon cloth layer. However, a significant anisotropy in the thermal conductivity values was the opposite. The 3D C-f/SiC-Al composite with low ceramic content (17 vol%) had a higher thermal conductivity in the X-Y direction (64 W m(-1) K-1) than in the Z-direction (34 W m(-1) K-1). The thermal expansion coefficient of all the 3D C-f/SiC-Al composites along the X-Y direction also decreased initially and then increased in the range of 100-450 degrees C, which presents low expansion characteristics.

Automated summary

3D C-f/SiC-Al composites were fabricated by infiltrating liquid Al-Si alloy into porous 3D C-f/SiC preform. Increasing the silicon carbide volume fraction resulted in lower thermal conductivity and thermal expansion coefficient, and the composites exhibited significant anisotropy.