二维C/C复合材料高温力学、热物理性能研究

Mechanical and Thermophysical Properties of Two Dimensional Carbon/carbon Composites at Elevated Temperatures

研究了二维C/C(2D -C/C)复合材料在高温下层剪强度、弯曲强度和模量、热导率和线膨胀系数的变化规律。结果表明 ,所制得的 2D -C/C复合材料的层剪强度随温度的升高变化不大、弯曲强度随测试温度的升高而增加 ;2 0 0 0℃的层剪强度、弯曲强度分别达到 1 4 .8MPa和 2 2 7.4MPa ,较室温分别提高了9.6 %和 6 0 %。弯曲模量在 1 0 0 0℃时增加到 39.4GPa ,在 2 0 0 0℃则下降 ,低于室温数值。 2D -C/C复合材料的热导率、线膨胀系数在z向和x -y向都具有明显的各向异性。未石墨化 2D -C/C复合材料 2 0 0℃的z向热导率是 4 .4 1W / (m·K) ,且随温度的升高而增加 ;而石墨化 2D -C/C复合材料 2 0 0℃的z向、x -y向热导率分别是 1 8.0 2W / (m·K)和 73.2 9W / (m·K) ,随温度的升高而下降。 2D -C/C复合材料在z向的线膨胀系数较大 ,80 0℃以内在 8× 1 0 - 6 /K～ 1 0× 1 0 - 6 /K之间 ;而在x -y向线膨胀系数在 80 0℃以内都很小 。

The change features in the interlaminar shear strength (ILSS),bending strength and modulus,thermal conductivity and coefficient of thermal expansion (CTE) of two dimensional carbon/carbon composites (2D C/C) at high temperatures are discussed. The ILSS and bending strength are improved at elevated temperatures, reaching 14.8 MPa and 227.4 MPa at 2 000℃ and increased by 9.6% and 60%, respectively. The bending modulus increases at 1 000℃ but decreases at 2 000℃. The thermal conductivity and CTE have characteristics of anistropy in x y direction and z direction. With test temperature increasing, the thermal conductivity decreases for graphitized 2D C/C butincreases for non graphitized C/C. It is about 4.41 W/(m·K) for non graphitized 2D C/C at 200 ℃ in z direction . For graphitized 2D C/ C, the thermal conductivities are 18.02 W/(m·K)and 73.29 W/(m·K) at 200℃ in z and x y directions,respectively. The CTE in z direction is 8×10 -6 /K to 10×10 -6 /K within 800℃, much larger than that in x y direction, which is near zero within 800℃.