Research On Mechanial Properties Of Ceramic Matrix Composites In Oxidation Environment

Ceramic matrix composites (CMCs) possess high temperature resistance, wear resistance, low density, and have broad application prospects on the aviation, aerospace, weapons, energy and other areas. It is important to perform the investigations on the mechanical properties of CMCs under oxidation conditions for the engineering applications.In this thesis, the mechanical properties of unidirectional fiber reinforced ceramic composites in oxidizing environment were investigated. The mechanical properties of C/SiC ceramic composites were analyzed by using the mass loss rate model under the oxidation of the temperature range 400~900℃, the shear-lag model, the Monte-Carlo simulation approach and the statistical fiber failure model. The residual stiffness under the temperature range of 400℃~900℃oxidation environments were predicted. The micromechanical methods were used to analyze the residual strength under oxidative stress factors.Below the matrix crack healing temperature, there are two kinds of oxidation mechanism: chemical controlled oxidation and the diffusion controlled oxidation. The thesis analyzed the oxidation residual strength with non-stress and stressed, residual stiffness and residual strength of a certain temperature are predicted.Experimental methods were used to investigate the high temperature 650℃and 800℃in air oxidation under non-stress mechanical properties and high temperature 650℃in air oxidation behavior under stress, compared to theoretical analysis and experimental results: predicted and experimental results.