Temperature-dependent changes in microstructure and properties of a carbon/carbon composite with an optional oxidation protection surface coating

For hot applications, materials which can withstand those extraordinary thermal loads are absolutely necessary. Carbon fiber reinforced carbon (C/C) materials are excellent candidates for structural components in aerospace industry. They possess a high specific strength and stiffness, which do not decrease as a function of the applied temperature. In this work C/C composites with different fiber orientations were investigated. The composites were fabricated via rapid-CVI process which fastens process times significantly and thus offers an economical alternative to conventional pyrolytic derived C/C materials. In order to prevent the material of oxidative degradation, an optional oxidation protection coating of SiSiC was applied. The oxidation properties as well as the mechanical behavior at high temperatures were examined, reflecting the significant challenges in real use. Thermogravimetric analysis was carried out and tensile tests on the material from room temperature up to temperatures of 1500 °C under nitrogen and air atmosphere. Furthermore, the interlaminar properties of the material was tested and a separation of the components, fiber and matrix, could be realized by appropriate test combinations. The microstructural investigation was carried out by scanning electron micrography and by X-ray diffraction