Effect of irradiation on mechanical properties of carbon composite materials

Abstract

Since carbon fiber reinforced carbon composite (C/C composite) materials have good mechanical properties at high temperature and low radioactivity under irradiated conditions, they have been used as the plasma-facing components in fusion facilities. Efficient utilization of these mechanical properties will lead to the use of c/c composite materials, these materials are expected for use as control rods for gas-cooled rectors and irradiating capsules. In the case of using c/c composite materials as the structural components, it is very important to evaluate the mechanical and thermal properties as well as fracture behavior. For structural components used in a reactor core, it is necessary to evaluate neutron-irradiation effects on these materials. However evaluation of these effects has been difficult, thus data on irradiated c/c composite materials are lacking. In this study, three kinds of c/c composite (CC-312, CX2002U and MCI) made of different fiber materials were irradiated under the condition of maximum neutron fluence of 2×1025 n/m2 and maximum irradiating temperature of 1200 °C, and the relationship between change of mechanical properties due to irradiation and the constitution of c/c composite materials was evaluated. In the case of CC-312 made of PAN fiber, Young's modulus changed slightly and bending strength after irradiation. In the case of CX2002U made of rayon fiber, Young's modulus and bending strength increased after irradiation. In the case of MCI made of pitch fiber, Young's modulus increased after irradiation, but bending strength decreased slightly after irradiation. These results enable the elucidation of the relationship between properties of fiber materials and irradiation effect on c/c composite materials.