高温氧化及热震对SiC/ZrB2-SiC/SiC涂层炭/炭复合材料力学行为的影响

为提高炭/炭(C/C)复合材料的高温抗氧化性能,同时分析涂层制备及高温氧化对涂层材料力学行为的影响,在C/C复合材料表面采用反应熔渗、料浆涂刷结合化学气相沉积工艺制备了SiC/ZrB2-SiC/SiC三层高温抗氧化涂层。利用SEM和XRD分析复合涂层的微观结构和相组成,考察涂层复合材料1500℃高温抗氧化和1500℃-室温的抗热震性能,研究高温氧化及热震对涂层C/C复合材料力学行为的影响。结果表明,复合涂层试样1500℃静态空气环境下具有优异的抗氧化及抗热震性能:1500℃氧化20 h后试样保持增重,1500℃至室温热震50次后增重为0.69%。因涂层制备过程中粉料的渗入反应,复合材料弯曲强度增长了7.08%。在经历1500℃氧化20 h和1500℃至室温50次热震后,涂层复合材料弯曲强度有所下降,且因材料界面结合力的减弱使得纤维拔出特征明显,材料塑性断裂特征增强。

Effect of high temperature oxidation and thermal shock on mechanical behavior of SiC/ZrB2-SiC/SiC coated C/C composites

In order to improve the high temperature oxidation of C/C composites,and analyze the effect of coating preparation and high temperature oxidation on the mechanical behavior of coated sample,a SiC/ZrB2-SiC/SiC multilayer oxidation protective coating for carbon/carbon composites were prepared by reactive infiltration,slurry and chemical vapor deposition.The microstructures of the as-prepared multi-layer coating were characterized by XRD and SEM,the anti-oxidation property at 1500℃and thermal shock resistance between 1500℃and room temperature of coated C/C composites were investigated.And the effects of high-temperature oxidation and thermal shock on the mechanical behavior of coated samples were studied.The results show that the as-coated samples can provide excellent oxidation and thermal cycling protection for carbon/carbon composites,which keep weight gain at 1500℃in air for 20 h,and also endure the thermal shock for 50 cycles between 1500℃and room temperature with 0.69%weight gain.The bending strength was increased by 7.08%because of the infiltration reaction of powder in coating preparation.After 20 hours of oxidation at 1500 and 50 thermal shocks,the bending strength of the coating composite decreases,and the fibers are pulled out obviously due to the weakening of the interface bonding of the material,and the plasticity of the coated samples increases.