Oxidation damage and residual mechanical properties analysis for Cf/ZrB2-SiC composites in thermo-oxygen environment

A diffusion–reaction damage methodology solved by finite element (FE) scheme is established to simulate the microscale oxidation behavior of carbon fiber toughened ultra-high temperature ceramic (C_f/ZrB₂-SiC) composites in high-temperature oxidation environment. The model is derived from the governing equations of mass conservation and diffusion–reaction kinetics theory, which are coupled by introducing effective diffusion coefficients and reaction terms. The apparent kinetic parameters are obtained from dynamic thermal analysis, which provide reliable data to simulate the reactive differences between the coating and the fiber. The oxidation weight loss of carbon fiber and oxidation damage of C_f/ZrB₂-SiC composites induced by matrix crack are taken into account in this model. The oxidation damage evolution is quantitatively described as a function of temperature, oxygen concentration and stress. The sensitivity of the oxidation controlling factors is analyzed comprehensively. The residual modulus of C_f/ZrB₂-SiC composites under different oxidation conditions is further predicted using the oxidation model combining with shear-lag model. This study can be helpful of improving the C_f/ZrB₂-SiC composites oxidation resistance design.