Influence of oxidation inhibitor on carbon-carbon composites: 8. Studies on thermal decomposition mechanism and thermal stability of composites impregnated with TEOS

In this work, thermal decomposition mechanism based on kinetic parameters and thermal stability of carbon fiber-reinforced carbon matrix composites(C/C composites), have been studied under high temperature oxidative conditions with addition of tetra-ethylorthosilicate (TEOS) as an oxidation inhibitor. Thermogravimetric analysis (TGA) was executed to evaluate the thermal decomposition mechanism and thermal stability of C/C composites in the temperature range of 30-850 °C. As a result, the kinetic parameters of the composites impregnated with TEOS, i.e., activation energy for thermal decomposition (E_d), order of reaction (n), and pre-exponential factor (A) were evaluated as 136 kJ/mol, 0, and 2.3×10⁹ s^-1, respectively. Especially, the IPDT and E_d of C/C composites impregnated with TEOS were improved largely compared with the composites impregnated without TEOS, due to the formation of SiO₂ on composite surfaces, resulting in interrupting the oxygen attack to carbon active site in the composites.