| Carbon/carbon (C/C) composites coated with anti-oxidation coating -exhibit excellent structural properties at elevated temperature (such as favorable strength retention ratio and high specific strength, etc.), and are considered as the most promising candidate using for high temperature application, especially using in the aeroengine industry. Unfortunately, present anti-oxidation investigations of coated C/C are focus on the isothermal protective properties in nature flow air (static environment), which could not characterize or evaluate the oxidation resistance of the protective coating working in an aeroengine combustion environment (dynamic environment). In order to expose the dynamic oxidation behavior and failure mechanism of the coated C/C, and find an effective way to evaluate or filtrate the coating using in dynamic environment, the low-level oxidation (weight loss less than 6%) property of C/C composites and the oxidation property of coated C/C in air, in single factor (temperature gradient or bending load) environment, in multifactor coupling (temperature gradient and bending load) environment and in combustion environment are investigated orderly in this paper. The main contents and conclusions are as follows:The isothermal oxidation tests of 2D C/C composites are performed with controlled weight loss (<6wt%) in air at temperature up to 1300℃. The experimental results indicate that material loss occurs preferential at fibre/matrix interfaces and defects in the C/C samples, resulting in defects increase, oxidizing depth decrease and bulk reduction. The low-level oxidation exhibits a linear rule and is quicken up with temperature rising. Through the oxidation kinetic analysis, the three-stage theory and the physical model about the low-level oxidation have been put forward and established respectively. Based on them, the influence of low-level oxidation on mechanical property of C/C composites is explored by the three point bending test. It is found that the flexural strength and modulus of C/C samples are increased first and decreased later with weight loss, development, which is similar to the effect of thermal shock cycle number on strength of C/C substrates.The SiC/glass oxidation protective coating has been firstly produced on the C/C composites by application of the pack cementation technique and the procoating-sintering process. Based on the study about the low-level oxidation of bare C/C, the static isothermal oxidation properties of SiC/glass coated C/C are investigated in air at temperature up to 1600℃. The results indicate that the SiC/glass coating has good oxidation resistance and thermal shock resistance, simultaneously, the coated C/C composites exhibit three oxidation-characteristic regions, including non-oxidation region (room temperature~450℃), defect-oxidation sensitizing region (450~1300℃) and intrinsic diffusion oxidizing region (1300~1600°C), due to the presence of the coating defects and the dependence of seal-healing capability of the SiC/glass on temperature. The oxidation-characteristic temperatures (OCT), such as oxidation threshold temperature (OTT), most sensitive temperature of defect oxidation (DOMST) and sufficient defect healing temperature (SDHT), are measured and approach to 450°C, 800°C and 1300°C, respectively. Through the comparative study, It is found that the coated C/C oxidized at 800℃ exhibits...
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